Accurate and On-Line Timing using Recurrent ...

98-E-ACI-136

Accurate and On-Line Timing using Recurrent Wavelet Neural Network for Power Systems M. R. Mosavi, N. Parya, and F. Teymoorian Department of Electrical Engineering, Behshahr University of Science and Technology, Behshahr 48518-78413

Iran Key words: Prediction, Timing Error, GPS, RWNN, Power Systems

Abstract

Global Positioning System (GPS) based time reference provides inexpensive but accurate timing and synchronization capability and meets requirements in power system fault location and monitoring. Global Navigation Satellite System (GNSS) signals from approximately eleven thousand miles above the earth provide a valuable fourth dimension-precise time. This universally available service is improved and changed the way many businesses accurately track, mange, and synchronize their operations. Precise timing, made available through GNSS, is playing an ever increasingly role in the expansion of time-critical applications on a global basis. Neural network have been established as a general approximation tool for fitting nonlinear models for input-output data. On the other hand, the recently introduced wavelet decomposition emerges as a powerful tool for functional approximation. In this papers, a Recurrent Wavelet Neural Network (RWNN) and its learning algorithm is presented for prediction of GPS receivers timing errors. This method is well suited for real time improving of GPS receivers timing accuracy. The proposed NN is implemented by a L1 GPS receiver. The experimental test results on the collected real data are presented and discussed in this paper. The experimental results emphasize that GPS timing error RMS can reduce from 300nsec and 200nsec to less than 183nsec and 51nsec by using RWNN prediction, before and after SA, respectively. Also, it is shown that performance RWNN is better than single WNN and single RNN. 1

98-F-ACI-251

Using Static Frequency Converters for Rapid Load Response in Pumped Storage power Plants S.M. Hassan Hosseini

S.A. Banihashem, Y. Sadeghzadeh

Islamic Azad University Science & Research Unit Iran Water & power Resources Development Co.

Islamic Azad University South Tehran Unit

Key words: Pumped Storage Power Plants, Static Frequency Converter (SFC)

Abstract

Electrical energy demands are varying daily, weekly, and even during a season. Therefore, power generation depends on intensity of its energy demands and the necessary energy can not be stored easily. The pumped storage power plants have a very great importance in having capability of storage of energy and economic power flow. Especially its application can make load duration curve to be smoother and it also improves power system stability and efficient. The idea is that the extra generated power in low load duration, pumps water to be stored in the upper dam to store potential energy, which its electrical energy can be extracted during need of it (specially in peak load). The generating unit can be assumed as turbine to generate electricity. As usual minimizing power loss and effective economical load dispatch has been one of objects in electrical industries, pumped storage power plants can make an important role in it. One of problem in such these power plants is to switches this plant to motor, condenser and generator modes by using static frequency converter method. The main goal of this paper is to analyze this kind of power plant which its main structure is with static starting (SFC) and the control strategies is using with controlling with micro computer system.

2

98-F-ACI-297

Nonlinear Predictive Control of Switched Reluctance Motor 1

A. Sadeghzadeh, 2B. N. Araabi 1. Niroo Research Institute 2. Tehran University Tehran- Iran

Key words: Switched Reluctance Motor, Nonlinear Predictive control, Commutation, Local Linear Neuro fuzzy Model Abstract

Switched reluctance motor (SRM) is a highly nonlinear plant, which is becoming an attractive alternative to conventional variable speed drives, due to its favorable advantages such as structural simplicity, reliability and low cost. However, SRM control is not a simple task, since the inductance of magnetic circuit is a nonlinear function of the phase current and rotor position. On the other hand, predictive control is a model based approach that uses the model of system to predict the future output according to future and previous inputs, as well as previous outputs. In order to apply predictive control strategy to real time control of SRM, the optimization process should be done as fast as possible. In this paper, to perform the optimization process as a quadratic programming, which is not as time consuming as a nonlinear programming, SRM is modeled as a combination of several linear models at and around each operating point. A local linear model is computed at each sample time then, and used to compute the control signal. As a result, the optimization process is a quadratic programming, which in absence of constraints can be done in closed form. Moreover, an energy term is added to the cost function. This added term not only provides a smoother control, but also results in a natural commutation between phases, without enforcing any external commutator. That is, the commutation process is done automatically through optimization process, considering the energy term in cost function. Simulation studies justify applicability of our proposed method to SRM applications. 3

98-E-ACI-371

Hierarchical DES Supervisory Control Approach to Micro grid Energy Systems A. Afzalian* and A. Nabavi Niaki+ * Dept. of Control Systems Engineering, Shahid Abbaspour University of Technology, Tehran, Iran + Dept. of Electrical Engineering, University of Mazandaran, Babol, Iran

Key words: Hierarchical Structure, Discrete Event Systems (DES), Micro grid Control

Abstract

Hierarchical structure is a common feature of control solutions of complex dynamic systems. In large discrete-event system (DES) hierarchical supervisory control, provides the higher levels controllers (manager) with simplified abstract models of the lower levels. Generation of electricity and associated loads can be considered as a subsystem or a “micro grid’ in large electrical power systems. This view to micro grid, suggests a hierarchical structure for its supervisory control and operation. During disturbances, the generation and corresponding loads can be separated from the distribution network, to isolate the micro grid from the disturbance (and thereby maintaining service) without harming the transmission grid’s integrity. The difficult task is to achieve this functionality without extensive custom engineering and still have high system reliability and generation placement flexibility. This paper discusses a hierarchical structure for supervisory control of a typical micro grid energy system. The processes and control tasks in each level is determined. We investigate the nature of information and command signals in implementation of the hierarchical supervisory control for a micro grid system. To design a supervisory control in each level, the plant and control specifications should be recognized and models as DESs. 4

98-F-ACI-502

Using artificial intelligence in power system voltage control A. Sina Jahad daneshgahi khoozestan

S. Mortazavi Chamran university

Key words: voltage and reactive power control, neural network, linear programming

Abstract

Optimum control of reactive power generation result in lower power loss which in turns implies better efficiency and power factors. The other important reason reactive power control is improving voltage profile. In this paper the usage of a neural network in reactive power control is proposed. In this neural network PQ buses voltages and power network loss are assumed as inputs and generators’ voltage, number of transformers’ tab and the amount of parallel compensators are as outputs. A comparative study with linear programming approach shows in better performance in less time.

5

98-E-ACI-553

Modeling and Prediction of Steam Pressure in the Boilers Using ANFIS A. Ashraf-Modarres 1, 2

H. Momeni 1

1.Tarbiat Modarres University (TMU), Electrical Engineering Department, Tehran, Iran 2. Iran Power Plant Projects Management (MAPNA Co.), Tehran, Iran

Key words: ANFIS, Modeling, Nonlinear System Identification, Steam Pressure, Combustion, Boiler

Abstract

Modeling of steam pressure in a boiler is important for many reasons. Steam pressure, which is a main factor affecting the total combustion system shall be constant in the presence of load variation. Using artificial intelligence methods for nonlinear processes modeling is an effective way for identification of such systems. In this paper the steam pressure of a boiler will be modeled using ANFIS. Simulation results demonstrate the effectiveness of the method.

6

98-F-ACI-634

Construction of Stator Resistance Estimator System Using DC Injection in order to Induction Motors Thermal Monitoring Hamid Reza Hafezi

Alireza Jalilian

Department of Electrical Engineering Iran University of Science and Technology Tehran-Iran Key words: Induction Motor, Thermal Monitoring, Estimation stator Resistance, Thermal sensor, DC Injection

Abstract

In this paper is proposed a system for induction motor thermal monitoring by stator resistance estimation. In this method the stator resistance is estimated with injection a small dc signal into line- connected motor. The impedance of an induction machine to a dc input in steady state is stator resistance. Therefore, if a small dc voltage bias can be superimposed onto the motor supply voltage to inject a dc current component, stator resistance can be estimated on-line using the dc components of the measured voltage and current. DC model based stator resistance estimation is independent of all motor parameters, and is not influenced by inherent motor asymmetry. Therefore, it provides the most reliable estimate of stator resistance for thermal monitoring. The simulation is performed in MATLAB software. This method tested on a 5.5 kW induction motor. Experimental results show that the accuracy of stator resistance estimation is approximately 1 percent. Also is shown that a better estimate of stator resistance can be obtained under heavier load conditions and if a larger value of Rext is used.

7

98-F-CAM-174

The Influence of Climate Conditions on Early Demolition of Hot Parls of konarak Gas Tourbines A . A . Asghari Moghaddam1 G . A . Rakhshani Mehr1

A . R . Kiani Rashid2 A . Alizadah Herfati3

1. Sistan & Baluchestan Regional Electric Co 2. Univrsity of Sistan & Baluchestan 3. Atlas Turbine Pars Co. Iran

Key words: Climate, konarak Gas Turbine, Hot Pouters - filter

Abstract

In our investigation about the climate conditions of this region, we use two ways of collecting datas which are aero logy reports and examination. Our results show that climate factors and arrive ness of impurity within sea water into different units of the power station, we have the most important factor of demolition. In regarding to this fact that air has the mast usenesl in gas units, if it contains small harmful impure particles, then after awhile, the turbines devices will facetiae considerable amount of contamination. Common filter system which is applied in the konarak power station, we face to two important problem and deficiency: firstly, these filters aren't capable of solving waters salt and the second, due to large volume of wet consumed air decreasing in humidity of common system has lost its efficincy. So it will be useful to have a proper filter system like D-Salt, which in addition to solving saltin water, is able to amit it. Regardless from changing in its design, using multi – bagged filters instead of one – baged filters, replacing the format of filters in order to decreas the possibility of entering contiminated air form space between filters and also change filters in shorter periods than before, and amiting small particles less than 2 micron, it can be said , our activities are proper, economic and useful in decreasing the amomnt of demolition in gas behaviour of konarak power station. 8

98-F-CAM-274

Fracture Analysis for Generator Cooling Fan Blades of Montazerghaem Powerplant Ali Jahangiri PWUT IRAN

Seyed Majid Yadavar Nikravesh Power & Water University of Technology IRAN

Key words: Gas Turbine, Fan Blade, Fatigue, Modal Analysis, Natural Frequency, Resonance

Abstract

Since the optimum operation of a generator is highly affected by increasing of temperature, a cooling system is used to control temperature. Employing a fan as a cooling system for the generator at the end sides of its rotor is a practical method. As the fracture of cooling fan blades has been occurred five times in our case study, in this research the emphasis has been placed on preventing methods of the fracture in a specified generator cooling fan blades. Survey and analysis of the above mentioned trouble has been done from different ways, which the main titles are as following: ● Metallurgical and structural analyses ● Studies on the ruptured surfaces using SEM ● CFD analysis. ● Modal analysis of blade Results analysis has shown that the fracture extreme of blades has been due to fatigue conditions in resonance state and growth of existent tiny probable cracks.

9

98-F-CAM-314

Applying of MCrAlY Coating by HVOF instead of LPPS in repair of gas turbine hot Component M.KHagheh S.T.C.Co. Key words: MCrAlY, Gas Turbine, HVOF, LPPS

Abstract

One of the main Processes in repair of gas turbine hot Components is Appling Coating on Part Surface. A Common way in decreasing of gas turbine blades failure, regarding to Situation of high stress and temperature, is applying MCrAlY Coatings on their Surfaces by LPPS technique. Since applying overlay Coating in this way needs high investment for equiption and maintenance of LPPS unit so that the expense of its purchase and maintenance is 10 times of that of HVOF, today other techniques such as HVOF are of special interest from economic aspect. From quality and economic point of view, HVOF can compete with LPPS. Nowadays, in shahriar Turbine Components Co. Which Works on repair of gas turbine components, applying overlay coatings on blades by LPPS technique is being carried out. Regarding to the presence of. HVOF system in this company, a project was carried out in order to study applying of Coating by this system in this article, MCrAlY Coating quality including the amount of porosity and oxides, adhesion of interface between Coating layer and base metal and surface roughness obtained by this system, on stationary and moving blades of MHI 701D gas turbine has been examined and Compared with that of LPPS system

10

98-F-CAM-316

Analysis of Premature Failure of 1st Rotating Blades of Ghom Power Plant MHI 701D Gas Units Davood Ghasemi Elahe Bani mostafa Nehdi Ghanbari Mohammad Mohammadi Shahriar Turbine Co,ponents Co. Key words: 1st Stage Rotating Blade-Thermal Fatigue

Abstract

After the first overhaul of MHI 701D gas unit of Ghom power plant, it was realized that all of 1st stage rotating blades were irrepairable and unusable anymore. It is attempted in this article, to determine causes of premature failure of 1st stage rotating blades of Ghom power plant MHI 701D gas units using gathered data about operation conditions of Ghom power plant and results of visual inspection, metallugraphic examinations, radiographic and stress-rupture tests, and regarding to these cause, solutions are given to prevent them from happening again.

11

98-F-CAM-496

Casting technology collection of first stage nozzle of gas turbine with 25 MW capacity M.R. Zamani Meighan (1) A. Samadi (1) H.Hoseinian (1) A. Kiani Rashid (2) S.F.Hazavehei (3) (1) TAJROBEH NOOR Production management of turbine components co. (2) Sistan & Baluchestan electrical regional co. (3) Tavanir Co

Iran Key words: Superalloy- FSX-414- Nozzle Gas Turbine-Investment Casting

Abstract

The aim of this investigation is developing the casting technology of first stage nozzle of gas turbine with 25 MW capacity, including pouring rate, casting temp, and pre-heating temperature of ceramic mould. This nozzle weighting 20 kg and including 5 airfoil is casted using precise casting. Because of the Chemical composition of FSX-414 alloy, this nozzle is casted in air and because of the variety of different sections in different places of nozzle (including shroud, and airfoils), a special heating regime was used during solidification in order to reduce the amount of defects in casting parts. The quality control of casting parts including radiography with X-ray, PT, chemical experiment was carried out to investigate the soundness of casting parts. In order to develop these casting parameters different experiments were carried out on experimental examples and fabric nozzles. After defining different casting parameters, the real casting were carried out.

12

98-F-CAM-530

Machining technology collection of first stage nozzle of gas turbine with 25 MW capacity M. Hosein zadeh1 G.Rakhshani mehr2

M.R. Zamani Meighan1 S. Bikass1 S.F.Hazavehei3

1. TAJROBEH NOOR Production management of turbine components co. 2. Sistan & Baluchestan electrical regional co. 3. Tavanir Co Iran

Key words: Superalloy, FSX-414, Superdrill, machining tools

Abstract

Machining difficulties of superalloys & specially FSX-414 Cobalt base superalloy, the material of first nozzle of 25 MW gas turbines, has been studied in this thesis. With attention to successful machining specification on thermal resistant superalloys, the suitable selection of tool material & geometry & machining parameters on machines is attained.There are different machining locations in first stage nozzle of 25 MW gas turbines that the suitable methods of machining are selected with attention to geometry & position of machining part locations, dimensions & capacity of industrial equipment, existent tools, accuracy & quality of surfaces & costs. These selected methods are grinding, traditional & cnc milling, spark & super drilling to nozzle machining.

13

98-F-CAM-548

Welding technology collection of first stage nozzle of gas turbine with 25 MW capacity

M.R. Zamani Meighan1 H.Hoseinian 1 G.Rakhshani mehr2

M.Memari 1 S.F.Hazavehei3

1. TAJROBEH NOOR Production management of turbine components co. 2. Sistan & Baluchestan electrical regional co. 3. Tavanir Co Iran

Key words: Welding, Superalloy, FSX-414, Nozzle, Insert, Retaining Ring

Abstract

In this investigation; welding technology of 25MW capacity of retaining ring and first stage nozzle has been developed. The position and dimension of welding blocks were studied and considering AWS standard, some parameters such as ampere, voltage, consumed gas and welding technique were characterized and quality control experiments and criteria including NDT and DT tests were developed. Using these welding parameters WPS and PQR forms for each kind of welding including wedge and groove type were prepared. Finally, the developed procedures and techniques were used in different positions. The results show that the welding parts has very good quality and mechanical properties. Also the WPS and PQR forms of different welding techniques are presented.

14

98-F-CAM-600

Situation of Inventory and Consumption of SF6 Gas in Iran electricity Industries, Comparison with World Consumptions and Necessity for using Gas Recycling Systems M.GHADIMI NIROO RESEARCH INSTITUTE IRAN Key words: SF6 Gas, Gas Insulated Systems, Recycling Service Cart Abstract

Gas insulated substation and switchgear using sulfur hexa- fluoride gas (SF6) are one of the best equipment in electricity transmission and distribution systems. The excellent insulating and quenching properties of SF6 gas have used in these systems have some advantages compared to other systems Base on study on the necessity of GIS substations, installation of about 120 GIS substations with 63KV capacity and 32 GIS substations with 132KV capacity are essential Up to year 2011. However, the experience acquired during the years of operation of these systems, signify special problems beside their advantages. These problems including: leak of SF6 gas from equipment, and environmental & economical effects of this phenomenon. Because of some SF6 by products that can be results from Arc & Corona faults in switching systems, have high toxicity and also considering that SF6 gas is expensive (25$/Kg) and have limited manufacturer. Furthermore another problem related to operation of these systems are discharging SF6 gas to environment during the maintenance programs. Due to present of some toxic by products and global effects of SF6 on ozone layer intentional releasing of this gas to atmosphere is not permissible. In the past years to overcome this problem, spent gas was stored in cylinders and sent back to gas producer. This process imposes some extra cost to units, furthermore due to storage & handling of gas in cylinders a portion of gas leak to environment. Now think that broached the subject of recycling used gas by mobile service cart, a major portion of this problem will be reduced. In this article the Inventory and consumption of SF6 in Iran electricity industries presenting and comparison with word statistics of production and consumption of this gas. In follow a necessity for using recycling cart has been studied. 15

98-F-CAM-700

Optimization of precursor powder size and preparation of superconducting Bi1.66 Pb0.34 Sr2 Ca2 Cu3 Oy wires H. Salamati- P. Kameli - I. Abdolhoseini – M.Madani* Department of physics, Isfahan University of Technology Esfahan Regional Electric Co.* Iran Key words: superconducting wires , PIT method

Abstract

In this paper we have prepared superconducting Bi1.66 Pb0.34 Sr2 Ca2 Cu3 Oy wires. First we have studied the effect of precursor powder size on the microstructure and intergranular behavior of polycrystalline Bi2223 superconductors using the XRD, SEM, electrical resistivity and AC susceptibility techniques. Polycrystalline Bi2223 superconductors were prepared from the powders with different milling times. The XRD results show that by decreasing precursor powder size the Bi2223 phase fraction increase. It was found that the grain size and grain connectivity improved by decreasing precursor powder size. Analysis of the temperature dependence of the AC susceptibility near the transition temperature (Tc) has been done employing Bean’s critical state model. The observed variation of intergranular critical current densities (Jc) with temperature indicates that the decreasing of precursor powder size in the Bi2223 system causes an increase in the intergranular critical current density. Second superconducting Bi1.66 Pb0.34 Sr2 Ca2 Cu3 Oy wires were prepared by powder in tube (PIT) method and their superconducting properties were studied.

16

98-F-CAP-123

Effective Phasor estimation algorithms for protective relaying within half a cycle of the power system frequency Sadegh Jamali1 Razmara Zakerifar

1,2

Hamid Sardari1 davoud talebi 1

1. Iran university science and technology 2. Mazandaran R.E.C

Key words: Digital filter , Half-cycle Fourier algorithm,Mimic filter

Abstract

Phasor estimation algorithms for protective relaying are required to filter out unwanted components from the input signals and retain only the components of interest. The components to be removed include harmonics and the decaying exponential transient component. They affect the accuracy and the speed of convergence for the phasor estimation algorithms to a great extent. This paper presents a new technique, which effectively removes the harmonics and the decaying dc component present in the input signals, within half a cycle of the power system frequency. This is achieved by means of determination of decaying dc components parameters. The performance is compared with the two most popular half-cycle phasor estimation algorithms; the half-cycle Fourier algorithm and mimic plus halfcycle Fourier algorithm. The test results show that the proposed relaying algorithm has a faster convergence and better accuracy compared to other algorithms.

17

98-F-CAP-162

Calculating the Corrective Factor of Frequency Relays in the Initial Step of Network Emergency Load Shedding Shahram jaded

Meysam Mashayekh

Center of Excellence for Power System Automation and Operation Iran University of Science and Technology Tehran-Iran

Key words: Frequency response, Load shedding, Frequency relay, Corrector factor

Abstract

In this paper initially, the system frequency response and the effect of various parameters on its changes such as over loaded conditions are modeled. Then, by considering network security criteria and determination of allowable frequency restrictions, the static and dynamic load shedding methods is analyzed. Next, an innovative method for computing the operation corrective factor of frequency relays is presented. Implementation of this factor in the primary step of load shedding, get the adaptive load shedding scheme in the curtailment sequence. Also, the obtained results during implementation of the correction factor in load shedding primary step are presented and analyzed.

18

98-F-CAP-224

Simulation and laboratory construction of an intelligent Ground transformer protective relay Mohammad Ali Karimi Fars Electric Company Iran

Hossein Mohseni University Of Tehran Iran

Farshad Faramarzi Fars Electric Company Iran

Key words: Intelligent Relay, Ground Transformer

Abstract

Existence of long power lines at the outgoing feeders of substations and occurrence of high-impedance faults and/or unbalanced voltages not recognizable by ordinary protections and there by resulting in drastic damages inflicted on Ground transformers in the long run are some of the most important problems prevailing sub-transmission networks . This paper outlines the design of an intelligent ground transformer protective relay which has led to construction of a laboratory sample capable of recognizing high-impedance faults , unbalances , leakage currents and initiating alarm and/or trip signals according to the characteristics of ground transformers before being damaged by above – mentioned factors.

19

98-F-CAP-302

A New Approach for Fault Detection and Classification in Transmission Lines Using Fuzzy Logic M. Afrashteh D. A. khaburi S. M. Shahrtash Center of Excellence for Automation and Operation of Power Systems Iran University of Scince and Technology Key words: fault detection, fault classification, transmission line, fuzzy logic

Abstract

This paper introduces a new approach for fault detection and classification in transmission lines based on fuzzy logic. The presented algorithm uses only phase currents, to detect and classify faults. To evaluate capability of this algorithm, the Alternative Electromagnetic Transient Program (ATP) is used to generate simulation data for the typical 500 kV transmission line in normal and faulty conditiones, the obtained results are compared with the results of two other algorithms. The results proved that the proposed algorithm is faster and more accurate than others.

20

98-F-CAP-463

Testing The effects of Harmonics on Digital and lectromagnetic Overcurrent Relays Hossein Kazemi Karegar Academic staff of Zanjan University

Reza Bayati Graduated Student

Electrical Engineering Department Zanjan University Zanjan-Iran

Key words: Digital Relays, Electromagnetic Relays, Overcurrent, Testing Harmonics

Abstract

Harmonics change the rms and the shape of the current goes through CTs and relays. Therefore, the operation time of the relays will vary from the value set before. In this paper, different tests have been done on digital and overcurrents relays to investigate the effects of the harmonics on these types of relays. Digital overcurrent relay AREVA manufactured by alestom and Electromagnetic overcurrent CDG11 manufactured by GE are the relays selected for testing. By relay tester type Omicron 256, different harmonics have been injected and the operation times of the relays have been recorded. The results showed that for coordination of the relays in power systems needs to use suitable filter that its characteristics will be explained.

21

98-E-CAP-551

Driving Vacuum Circuit Breaker Using Output Current of Current Transformer Behrooz Rezaeealam University of Lorestan IRAN Key words: Fault current , current transformer, vacuum circuit breaker

Abstract

When the electrical fault, such as short-circuit or overload current, happens in the middle voltage network, a current transformer detects it and the vacuum circuit breakers (VCBs) quickly open and interrupt the fault current (tripping). Recently, electromagnetic actuators are widely used as operating mechanism for the VCB. In this paper the possibility of the direct tripping of the electromagnetic actuator by the current output of the current transformer is investigated numerically. In simulation, the secondary current waveform was calculated by response surface approach. It can take into account of the saturation effect of the magnetic core due to high primary current and heavy loads of the secondary circuit. The mechanical behavior of VCB in time was also simulated coupling with the actuator motion and the operating electrical circuit. Finally tripping tests by the current transformer output with high primary current was performed.

22

98-F-CAP-598

Determination of Fault Location and Bus Voltages During Voltage Sags Using Optimal Measurements Hosein Askarian Abiane Yaser gerivani Kazem Mazlumi Amirkabir University of Technology Iran Key words: Power quality, stochastic assessment, voltage sag, optimal monitoring

Abstract

In this paper a method for determination of the place of fault location on non-monitored buses is described first. Then the voltage values of nonmonitored buses are estimated. To do that by using the voltages of monitored buses, an algorithm named estimation algorithm is developed. The method is applied to an actual 230 kV Tehran regional company and the result will be outlined.

23

98-F-CAP-638

A New Method Based on Discrete Wavelet Transform and Fuzzy Inference System for High Impedance Fault Detection S. Mortazavi I. Saadinezhad M. Mohseni Dept. of Electrical Engineering, Shahid Chamran University, Ahwaz, Iran Key words: High Impedance Fault, Discrete Wavelet Transform, Fuzzy Inference System

Abstract

This paper presents a new method for High Impedance Fault (HIF) detection. In this method, Discrete Wavelet Transform (DWT) is used for the decomposition of three phase current signals and feature extraction. Then, a Fuzzy Inference System (FIS), with three criteria of DWT coefficients as the inputs, is used for classification. Finally, several simulation cases have been conducted by PSCAD/EMTDC to verify the sensitivity and security of the proposed method. Results show high efficiency of proposed algorithm in identifying different HIFs and immune to other typical power system events such as load switching and capacitor bank switching.

24

98-F-CAP-659

Study on Required Superconductor Volume in Flux Flow Type Superconductive Fault Current Limiter H. Heydari

R. Sharifi

M. Safdari

Center of Excellence for Power System Automation and Operation Iran University of Science & Technology, Iran Key words: Flux Flow Resistance, Required Volume, High Temperature Superconductor, Fault Current Limiter, SFCL

Abstract

Fault Current is important in power systems because short circuit current is very high. Recently, after progression to manufacture high temperature superconductor materials, experts improved their efforts to construct fault current limiters. Fault current limiters are equipments which have no effect in the power system at normal condition but after a fault occurs; current is limited by insertion relatively large impedance through its path and current don’t exceed to a specified amount. Because superconductivity behavior, superconductor fault current limiters can be divided to two main groups named resistive and inductive that flux flow is a kind of resistive type. In this paper after revision to using flux flow fault current limiters, effect of material volume of SC on fault current limitation factor and required time for removing fault discussed and results for a sample 20 Kv system proposed.

25

98-F-CAP-704

Optimal Overcurrent Relay Coordination in an Interconnected Power System Considering Different Topologies Using a Hybrid GA Habib rajabi mashhadi

Javad sadeh

Abbas saberi noghabi

Electrical Engineering Department, Ferdowsi University, Mashhad, Iran with cooperation Central Committee of Research of Electrical Utility of Khorasan

Key words: Overcurrent Relay Coordination, Genetic Algorithm Different Topologies, Power System Protection

Abstract

The problem of overcurrent relay coordination is one of the most important one in power system protection. The solution of this problem is usually done by fixed network configuration. In practice, because of changing operation conditions or line outage, network configuration is not fixed. And the network is operated by different topologies. So, coordination based on fixed configuration, don’t satisfy relay coordination in other network topologies. In this paper, by developing usual methods in relay coordination and adding different network configuration constraints in problem formulation for solving this problem, a new method is proposed. Also instantaneous constraints is considered in overcurrent relay modeling. Coordination problem is a complexed optimal nonlinear one. To solve this convex problem and attaching to optimal solution, GA method can be used. To increase searching space and increase calculation efficiency of GA, in this paper, hybrid method, GA and LP, is used. At the end, the proposed method is applied to an 8-Bus network and the results in different cases are compared.

26

98-F-CAP-788

Failure Analysis for transmission network reliability study Niki Moslemi

Davood Jalali

Hamid Danaee

Felor Nikoorai

1. Niroo Research Institute 2. Azerbaijan Regional Electric Company Key words: reliability, failure analysis, component indices, interruption indices

Abstract

Reliability study is one of the important studies of power systems. By reliability analysis the weak points of the network can be determined .The quantitative reliability evaluation permit reliability component indices to be computed from failure analysis of the constituent components of the system and interruption indices in all load points to be calculated from interruption data of outage in past time. In this paper is explained that how can use the results of reliability studies in the transmission network operation and design and whit attention to the reliability analysis results, some offers are produced for increasing the reliability of network. The Azerbaijan transmission network is considered as case study.

27

98-F-CAP-818

Performance Study of Local Protections during Power System Oscillations Mohammad Chehreghani Bozchalui Majid Sanaye-Pasand Mahdi Davarpanah Department of Electrical and Computer Engineering, University of Tehran

Key words: Oscillation, Angle instability, Local Protection, Power Swing Blocking

Abstract

In this paper, performance of local protections during power system oscillation is studied. Behaviors of distance protection, over current protection, auto reclosers, frequency relays, out of step protection, loss of excitation and other protections of generators are investigated. Also operation of distance protection schemes such as DCB, POTT, PUTT, DUTT and protection schemes based on phase comparison, which are used for unit protection of transmission lines are simulated and their performance during power system oscillation and angle instability are discussed. A part of Iran Electrical HV Grid, Khorasan Regional Electric Co. 400 Kv network, and some parts of 132 Kv grid of its network is simulated in EMTP/ATP. Operation of local protections has been investigated for different oscillations caused after occurring and clearing different faults in the grid. Different simulations and their results are presented and behaviors of different local protections during oscillation are discussed.

28

98-F-DTC-160

Implementation of teleprotection system for using in digital PLC Maryam Shabro Communication Dept., Niroo Research Institute Tehran-Iran Key words: Protection System, TPS and digital PLC

Abstract

Teleprotection system (TPS) is used for disconnecting both sides of power lines when a fault occurs in the network. In such systems, protection data or commands are transferred via appropriate communication media. Fast, accurate and errorless operations are mandatory in this system. Teleprotection system is an intermediate between protection system and communication facilities, so it contains intermediate part with protection system in substations and with communication media and processing and decision-making parts. The implemented teleprotection system for plugging with digital PLC is a two-command system (it can transmit A, B, A+B commands) and it uses the PLC pilot as a guard signal and the base band as a commands channel and it doesn’t need extra bandwidth. All the processing, decision-making and interface with transmission media (digital PLC) are completely implemented by a DSP processor. Software programs are prepared with modeling the tasks of TPS that in system powering up, those programs are located in processor’s memory via central computer control ISA-Bus in digital PLC system. In this case changing the system parameters (Such as transmission time, transmission duration, duration of commands, duration between tests, … ) are accessible with changing the software. With the aid of software, the hard ware of this system is minimized, so in addition to improved the quality of system, some production problems like cost, adjustment and factory tests are decreased. 29

98-F-DTC-299

Automatic Meter Reading Using Short Message Service Abdollahi Ali, Zamanzadeh Negar, Dehghani Marjan Niroo Research Institute Tehran - Iran Key words: AMR, SMS, OBIS

Abstract

In recent years extensive researches have been made in connection with Automatic Meter Reading (AMR) applications and different reading media like radio, telephone network and power line have been used. Nowadays, the advent of GSM network and its immense coverage in most countries has resulted in introduction of this network as a general medium for wireless communications. Using GSM network in machine-to-machine communications has provided new contexts for mobile network operators, one of which is AMR system. At present automatic reading of residential meters using this approach is not economical, however it is thrifty for commercial and industrial (C&I) meters. This paper describes automatic meter reading via short message service that has been recently implemented by Niroo Research Institute (NRI) and portrays prominent features of the system.

30

98-F-DTC-331

Choosing the Appropriate Protocol for Electrical Distribution Automation Projects in IRAN Mehdi Kavousian Niroo Research Institute Key words: Tele-communication Protocol, IEC 60870-5-101, DNP 3, SCADA, DA, Electrical Distribution Network, Telemetry

Abstract

This paper investigates the possible protocols for automation of Iran’s electrical distribution networks. Declaring the importance of selecting the protocol in these projects, we introduce two major protocols in this field. We remark IEC 60870-5-101 and DNP 3 specifications with a focus on differences. Then we study the issues for electrical distribution network and special regional problems in Iran. Afterwards by mapping these issues to the protocols differences we summarize the discussion. As a result, considering factors such as achieving of functional requirement, simplicity, support and geographical popularity, we conclude that the appropriate protocol for this application is IEC 60870-5-101 for current projects. In case of availability of TCP/IP backbone, IEC 60870-5-104 and in future IEC 61850 protocol may be used.

31

98-F-DTC-469

Implementation of Alarm/Event Sub-System in SCADA Software Using Amir Tavakkoli NRI – Control and Power Management Dept. Iran Key words: SCADA ،HIM ،DAIS ،Alarms/Events ،OPC, Software Development

Abstract

Alarm/Event processing and Alarm/Event viewing are two important subsystems of SCADA software. In SCADA software development, data organization and data exchange are to important subjects. Former SCADA products had their dedicated data model and data exchanging mechanisms. Now a days, CIM as a standard data model, is released by EPRI to organize information of SCADA and other power application softwares. Using standard data models to organize SCADA information provides some facilities in storing data and sharing data between some applications. Also, using standard software interface can be helpful in communication between SCADA sub-systems. To exchange data between two parts of SCADA, DAIS that is a new standard software interface has been relased. In this paper, I will explain CIM and DAIS firstly. After that implementation of Alarm/Event Processing and Alarm/Event viewing will be explaned and usage of CIM and DAIS in these sub-systems will be explained.

32

98-E-DTC-515

Online Optimal Load shedding for automation of Distribution Networks A. R. Malekpour

A.R.Seifi

M. R. Hesamzadeh

Shiraz University

Shiraz University

R&D Department Nirou Trans Company

Key words: Online Load shedding, Optimization

Abstract

This paper discusses a genetic algorithm (GA) based online optimal load shedding problem at the electrical power distribution systems, due to capacity deficiency conditions caused by unscheduled outages in the bulk generation and transmission (G&T) - system. The objective is to minimize the sum of curtailed load and also system losses for a given generation within the frame-work of system operational and security constraints. For variety decrease in supplied power to the distribution network the result has been saved to be used for online optimal load shedding applications. The proposed method is tested on a radial distribution system with 33 load points for more practical applications.

33

98-F-DTC-546

Study of FHSS & DSSS Communication methods efficiency in electrical substation Mohammad reza Tajdani FREC

Ali Reza sookhak FREC Iran

Key words: Spread spectrum, DSSS, FHSS, Swithing noise, Antena gain

Abstract Todayَ s available processing power and well-developed signal processing

algorithms promise a new paradigm for more reliable communications serving power generation, management and transmission. The following list indicatses some basic advantages of using a wireless system iver a cables system in substation applications. Substation switching operating, corona effect, and gap discharge breakdown are among the major causes of high frequency electromagnetic interferences which directly impact wireless communication quality.Furthermore,the radio wave propagation influences wireless communication in substations in several ways.Antenna gain, size, and electrical isolation and grounding are among the major concerse in this paper. The impacts of external environmental condition (such as a wide fluctuation of tempration, high humidity, excessive vibration, and significant pollution) are also of interest.

34

98-F-DTC-568

Finding the best path for data exchange in industrial control networks Roja Fooladi Mahmoud Ahmadian Behrouz Hajian Nezhad Coding & Cryptography Lab., K.N.Toosi University of Technology Key words: graph, Floyd-Warshall algorithm, communication media, data exchange protocols, industrial network security

Abstract

Power networks are the main part of all energy systems. In these networks data is exchanged between control centers, generators, substations and other equipments. Safe data exchange is an important parameter for working the power network correctly. In this paper we first introduce a graphical representation for power networks, where nodes are control centers, generators, 400kv substations and some communication systems. The branches of this graph are weighted according to communication safety and reliability. Some important parameters are: data exchange protocol, quality of services in the communication channel, data rate, security, …. By employing Floyd-Warshall algorithm, we designed a simulation program to find the best path for secure transferring data through this graph. This algorithm then examined by some examples base on a prototype graph.

35

98-F-DTC-714

OFDM1 System Simulation and Channel Equalization in Power Line Communication Systems H. Atefatdoost*, M. H. Ghamat **, A. R. Zolghadr-Asli** *

**

Fars Regional Electric Company, Dispatching Group, Shiraz, IRAN Dept of Electrical Engineering, School of Engineering, Shiraz University, Shiraz, IRAN

Key words: OFDM, Power Line Carrier, Impulsive Noise, Fading, Channel Estimation, Receiver

Abstract

The impulsive noise and multipath effects are the main reasons which cause the bit errors in power line communications (PLC) systems. PLC systems simulation as a media of data transmission in electric power systems, have been studied in this paper. Simulation results show that by using OFDM and suitable channel estimation and equalization technique, we can access to the higher data rates and reliable services to suppress the multipath and impulsive noise effects and attain a lower BERs.

1. Orthogonal Frequency Division Multiplexing

36

98-F-DTC-751

Study and simulation of COFDM performance in Power Lines communication Dariush Abbasi-Moghadam PHD student of Iran University of science and Technology Tehran, Narmak, Iran University of science and Technology (IUST)

Vahid Taba Taba Vakili Associate Professor of Electrical Engineering, Department of Electrical Engineering, Tehran, Narmak, Iran University of science and Technology (IUST)

Key words: COFDM, Power Line, impulse noise, Multi-path

Abstract

There are different problems in data communication in power line communication channels due to frequency selective property and destructive phenomena like multi-path, fading, noise, attenuation and distortion. Therefore it needs serious activities to be done against those impacts to achieve an ensured data communication. One of the suitable techniques is COFDM which can conquer those problem because of using multi-carriers and error correction techniques. In this paper COFDM performance in power line is studied. For this reason, the effects of different parameter on COFDM performance are simulated. Some of these effects are delay, multi-path fading, peak power clamping and their effects on COFDM are simulated. Simulation results show increment in carriers number cause serious enhancement in the performance of system. Also you can see that COFDM have a good performance ever in M-ary modulation scheme.

37

98-F-DTC-756

OFDM in Power Lines and Evaluation of Distribution Line Effects on This Technique Vahid Taba Taba Vakili Associate Professor of Electrical Engineering, Department of Electrical Engineering, Tehran, Narmak, Iran University of science and Technology (IUST)

Dariush Abbasi-Moghadam SAIran communication Industries Tehran, Noboniad sq,Langari st, Iran

Seyed Mohammad Razavizadeh PHD. In communication research center Tehran, North Kargar Street

Zohrah Mohades Student of communication engineering in shahid Bahonar University Kerman- Shahab Street, electrical department

Key words: OFDM, Distribution Line, impulse noise. Multipath

Abstract

Power distribution lines can be used as data transferring channels. Power line channel is a frequency selective channel, and has high noise and distortion levels. Use of OFDM technique can overcome these effects due to its multicarrier structure which allocates a small bandwidth to each subcarrier. In this paper, the effects of various power line parameters in data communication by OFDM technique are studied and the simulation results are presented.

38

98-F-DTC-905

Specificity of Communication Systems of Bushehr Nuclear Power Plant Azin Laknejadi, Saeed Kheirollahi Ofogh Consulting Engineers Electrical and Communication Engineering Dep. Key words: Wire & Radio Communications, Redundancy

Abstract

The ever advancing nature of tools used in the fields of communications and information exchange in this age, especially in sensitive industries such as aerospace, nuclear power generation and particularly the complicated military applications, emphasizes the need for better understanding of these tools. Since the nuclear industry is a modern, sensitive and accurate industry, the need for fast, reliable and accurate communications, any noise or false signal is a prerequisite for effective and timely communication of information and broadcast of warnings at the time of danger. This article attempts to compare the communication requirements between the nuclear and conventional power plants to provide an overview of the distinct technical characteristics for the communications systems of the Bushehr Nuclear Power Plant as an example. The reliable communications in the Bushehr Power Plant is accomplished using redundant systems (systems that are completely independent from each other and use different design and equipment so that no common cause may concurrently affect them) so that upon losing one of the systems, another system is immediately available for use. Considering the need for continuous and safe utilization of the nuclear power plant, the article emphasizes the need for the appropriate media for communications within the plan as well as to outside.

39

98-F-DTC-909

Design and Implementation of an Optimum Distribution Line Carrier Modem Using for Distribution Automation System Milad Amir Toutounchian, Behrouz Daneshkhah, Sahar Rakei Niroo Research Institute (NRI) Iran Key words: DLC Modem, Distribution Network, Distribution Automation, OFDM Modulation, Automatic Routing Abstract

Distribution network, in spite of undesirable conditions like signal attenuation and varying line impedance, is interested for researchers as a low cost communication media for years. Distribution electric companies are looking for utilizing distribution automation systems (DAS) in order to increase efficiency and reliability and to decrease maintenance and operation costs. In the presented paper, by using DSP technology, a distribution line carrier (DLC) modem was designed and implemented for transmission data over distribution power line for DAS application. Because of time-varying channel and line impedance characteristics and operating on noisy conditions, this modem was designed based on OFDM1 modulation. The proposed modem provides sub-carrier selection capability to make a reliable high-speed connection. The designed system is linked to 20Kv lines via a coupling capacitor. The modem can operate up to 148Kbps. Depending on the number of substations and their structures this modem can transmit data up to maximum 10 kilometers distance. To increase transmission range, up to seven modems can be worked together to configure a DLC network, consequently a network manager protocol, which provides automatic network routing, has been considered as a main feature of designed DLC modem. All of the modem parameters can be set through Windows platform software. The introduced system is in conformity with IEC-61334 standard. 1. Orthogonal Frequency Division Multiplex

40

98-E-DTC-915

Applicable Routing Protocols in Wireless Mesh Networks for the Energy Industry Kaveh Shafiee Hodjat Toraby Veesta World Co. Key words: SCADA, WMN, DCS, Routing protocols, AMR

Abstract

In energy industry, data collection and control systems which are named Supervisory Control and Data Acquisition (SCADA) systems have traditionally been labor intensive. Moreover, they have large up front infrastructure which imposes capital costs and ongoing monthly expenses. Over the time, many offerings have been proposed in order to reduce the costs of these systems. Reducing overhead costs associated with manual energy information collection and control methods has been one of these cost reduction offerings. These energy conservation and cost reduction needs have communication requirements essential to successfully meet Dispatching Control Centre needs. Among wireless networks wireless mesh networks (WMNs) are the best selection. WMN is a collection of wireless local area network (WLAN) devices connected through wireless links without preexisting infrastructure. The nodes have the ability of topology learning and self-configuring. In this article we first propose a wireless mesh network in energy industry and later on we concentrate on the state-of-the-art applicable routing protocols in this system which are the main concern in using these systems in practice.

41

98-F-ELM-103

Optimizing the thermal design of switch reluctance motor with finite volume method M. Tiourad1, S. S. Ziaee2, M. Soltani Hosseini3 Niroo Research Institute, Mechanical Systems Group Iran Key words: Switch reluctance motor, Computational fluid dynamics, Optimization in heat transfer Abstract

In electric motors, the most important problem that can pull down them is burning insulator of coils and insulator between stator poles and coils. Therefore, we must be sure that maximum temperature of motor is lower than its critical temperature. Designing pellicle and bonnet for this motors, is very important and vital problem. Whatever the holes are larger, heat transfer from the coils is better and this increase the pollutions income to the motor and decreases the coils life. In this paper, target is designing the switch reluctance motor and obtaining the optimum design for pellicle and bonnet. For this purpose at first, we analyze the flow and heat transfer in a narrow space between two concentric cylinders where the outer one is fixed but the inner one is rotating. Then Nusselt numbers have been compared with experimental results that have showed acceptable agreement. After this validates and proves the accuracy of procedure, the real model has been analyzed. For this purpose five different conditions has been surveyed. In the first condition, the motor has been assumed without bonnet and with hole on pellicle. In the second condition, the motor has been assumed with pellicle and bonnet and without any holes on them. In third condition, the motor has been assumed with holes on pellicle and without any holes on bonnet. In forth condition the motor has been assumed with holes on bonnet and without holes on pellicle and in the last condition, we assume that motor has been worked with pellicle and bonnet and holes on both of them. Finally, considering the results 1425 rpm and 950 rpm, the best pellicle and bonnet has been chosen. The accuracy of results, mesh independency has been checked and, the results for optimum design have been presented in thermal, velocity and pressure contours. 1. Author, Student of Sharif University of Technology 2. Project Manager 3. Head of Power Generation Institute, NRI

42

98-F-ELM-138

Unbalanced magnetic Pull Analysis in three phases Induction machine Due to Eccentricity by Winding Function Method Sadegh Shamlou * Mohsen Shamlou ** Batool Orouji ** * PHD Student of Amirkabir univ. ** Electrogen Co. Iran Key words: Unbalanced Magnetic Pull, Static, Dynamic, Mixed Eccentricity, Skew, Winding Function Method

Abstract

Any kind of electrical, mechanical and magnetically unbalances cause Unbalanced Magnetic Pull in electric machines. Heretofore, many papers have been presented to analysis of causes and effects of UMP in electric machine based on different experimental and theoretical methods. Several researches on modifying Winding Function Method make it powerful, fast and accurate method to analysis electrical machines. For the first time, in this paper, effects of all kind of static, dynamic and mixed eccentricities, rotor skew and loading effect in three phase induction machine on UMP have been presented by means of modified winding function method that includes slot effects, magnetic intensity variation along airgap, real mmf function over slots and real airgap function of eccentricity.

43

98-F-ELM-150

A Novel Synchronous Generator Model for Dynamic Analysis Ebrahim Karimi

Ahad Kazemi

Iran University of Science and Technology Tehran-Iran Key words: Mathematical model, synchronous generator, dynamic analysis, orthogonal dq-axes

Abstract

Mathematical models of physical devices are abstractions of reality. Their purpose is to portray, with sufficient accuracy and simplicity, the important characteristics of the systems under consideration. For synchronous machines, relatively low-order models may be employed to predict their steady state or dynamic behavior, with the orthogonal dq-axes theory used in the majority of cases. Over the years, different models have been proposed to represent phenomena related to the distributed circuit behavior of rotor windings, magnetic saturation, and saliency related issues. However, the common thread among them is that they were focused on a problem and thus, limited by that. Analyzing synchronous generator transients, it can be seen that resulted voltages, currents and electromechanical oscillations differ from its actual quantities. By correcting second order d-axes parameters of synchronous generator model digital simulations led to more accurate results. In this paper suggested dynamic model results simulated by MATLAB SIMULINK TOOLBOX will compare with second and forth order synchronous generator dynamic model obtained from literature.

44

98-E-ELM-169

Rotor position Detection by Employing Pulse Injection Technique on switch Capacitor in Switched Reluctance Motor H. Moradi Cheshmeh baygi and E. Afjei Dept. Electrical & Computer Engineering Shahid Beheshti University, Saadat Research Institute Iran-Tehran Key words: Switch Reluctance motor, Sensorless operation of SRM, Indirect rotor, position sensing in SRM

Abstract

This paper presents a new and novel method which is designed to detect the rotor position at standstill and also low speeds in switched reluctance motor. In this method a small capacitor is connected in series with the motor winding. The supply voltage in conjunction with the drive transistor produces short pulses for this series connection. The phase inductance varies with the rotor position, therefore the rise time of the voltage produced on the capacitor changes. Now the capacitor voltages are compared with a pre-set voltage value and the rotor position is detected at standstill mode. It then continues to sense the rotor position while the motor running by applying the same procedure but only to the un-energized phases winding. The results obtained demonstrate the feasibility and practicability of the method.

45

98-F-ELM-203

PERFORMANCE OF MOTOR AND MOTOR-DRIVE UNDER VOLTAGE SAG CODITIONS Hana Gholamreza, Shokrollah Shokri Kajoori Faculty of Electrical Engineering -K.N.Toosi University of Technology Iran Key words: voltage sag, induction motor, dc-link voltage

Abstract

In this paper, different types of voltage sag are produced in software environment and applied to the motor and motor-drive set. By changing the start point of voltage sag, the performance of induction motor (variations of current and torque peak and speed loss) is investigated under voltage sag conditions .Certain points in one period has been determined as the best or the worst initial points of voltage sag. Also effect of different loading levels on current and torque peak and slip are studied. A new classification of voltage sag is presented according to behavior of induction motor under different voltage sag conditions .Finally, the effects of capacitor value and line reactance value on the performance of motor-drive set (variations of dc link voltage, current and torque peak and speed loss) are studied under voltage sag condition.

46

98-F-ELM-276

Performance Improvement of the Axial-Flux Permanent Magnet Disk Generator by the Modification of Its Structure Seyed Mohsen Hosseini, Mojtaba Agha-Mirsalim, Mehran Mirzaie Electrical Engineering Department, Amirkabir University of Technology Tehran, Iran Key words: Disc Generator, Axial Flux, Magnet, Rotor Tooth, Design, Stator Core

Abstract

In this paper, the novel structure for the disc permanent magnet generator, which was previously presented by the authors, is modified for better performance. The new generator has two outer rotor discs and one coreless stator in the middle. The unidirectional magnets, which have circumferential direction of magnetization, are glued inside the slots of the rotors. To obtain better performance, a semi-sinusoidal tooth is made between a magnet and a slot on the iron of the rotor. It will be shown that the change in the structure, decreases the eddy current losses while increasing the output power and hence, an increase in the efficiency of the machine.

47

98-F-ELM-373

A New Approach in Modelling and Design of Axial-Flux Permanent Magnet Machines Mohammad Mardaneh

Mojtaba Mirsalim

Mehdi AliAhmadi

Key words: Axial-Flux Permanent Magnet Machine – Analytic Model – Finite Element Method – Genetic Algorithm - Optimum Design

Abstract

In this paper, a new analytic approach to the calculation of magnetic field in a slot-less, two-rotor axial-flux permanent magnet machine is presented. The analytic modelling is based on calculation of scalar and vector magnetic potentials which are produced by the armature windings and the magnets. The magnet and the armature windings are modelled by a magnetization vector and a two dimensional current sheet, respectively. The effects of the armature reaction and the harmonics of field are also considered. The simulation of magnetic field by the analytic model is compared with the two-dimensional finite element analysis. The proposed analytic model predicts the magnetic field within %5 compared to the finite element method. Ultimately, by using the analytic model in a genetic algorithm method, an optimum design of an axial-flux permanent magnet machine is presented.

48

12-E-ELM-434

Stator Winding Partial Discharge Activity or Different Manufacturers And Winding Ages Earl Goodeve and Vicki Warren Iris Power Toronto, Ontario Canada

Key words: partial discharge, motor, generator

Abstract

Partial discharge activity has long been known to be an indicator of the presence of some deterioration mechanisms at work within, or on, the solid insulation of the stator windings of high voltage rotating machines. Initially the detection and use of the information or signals provided by these discharges relied extensively on the expertise of a few individuals and was very subjective in nature. Comparisons between different machines, or even between tests taken on the same machine over time, was highly one-sided and made firm conclusions or judgments difficult to make. Advances in on-line detection and measurement of partial discharges has resulted in monitoring equipment that provides a knowledgeable user with reliable and repeatable information regarding the behaviour of an insulation system while a machine is in operation. These non-intrusive tests have the capability of providing a wealth of information, which can be useful to formulate priorities and develop an appropriate maintenance strategy, especially where many machines are involved. This paper will highlight some of the observations and benefits of on-line PD testing using the results of more than 80,000 unique tests on rotating high voltage machines.

49

98-E-ELM-440

The Induction Machines Modeling Based on Bars Current for Rotor Fault Analysis Payam Alemi1

Jalal Nazarzadeh2

1. M.S Student of Islamic Azad University Science & Research Branch, Tehran, Iran 2. Faculty of Engineering, University of Shahed, Tehran, Iran

Key words: Induction Machines, Bars Current Modeling, Bar Broken, Simulation.

Abstract

The induction machines are most widely used in industrial, commercial and residential sectors. These machines work under various operating stresses, which deteriorate their machine conditions giving rise to faults. The characteristics of an induction machine change when there is interior faults. Recently the induction machines modeling for rotor fault analysis are based on mesh-current model and experimental results but the approaches are very complex and expensive. In this paper one type of interior faults such as broken squirrel-cage bars is presented. A model base on the rotor bars current is used to simulate an induction machine. A three-phase induction machine is used to study under normal healthy operation, and with one broken rotor bar. The simulation results illustrated noticeable modulations in three phase stator currents and low frequency harmonic modulations in electromagnetic torque and rotor speed. Low frequency harmonic modulations in steady-state condition are more visible than starting condition.

50

98-F-ELM-444

Studying Effects of Dynamic Parameters of Synchronous Generators on Its Short-Circuit’s Behavior E. Sharifi Ghazvini

E. Khosrowshahli Niroo Research Institute Iran

M. Mirzayee

Key words: Synchronous Generator, Short Circuit, Transient States

Abstract

In this paper, effects of changes in electrical and mechanical parameters of a sample synchronous generator, such as resistances and leakage inductances of stator and rotor, excitation voltage and total inertia of rotor, on its terminal currents has been studied. And, with studying the profile of shortcircuit current characteristics of a short-circuit generator has been derived. Sample generator is a 400V, 2MVA synchronous generator, which has been studied with d-q model of synchronous machines.

51

98-E-ELM-556

A Study to Estimate Generator Armature Leakage Reactance Using Potier Approximation M. R. Bank Tavakoli

H. Gharagozloo

Amir Kabir University of Technology

Tarbiat modares University

M. Zare Garizi

A. R. Mirzaei

Iran Grid Management Co.

Tehran Regional Electric Company

Key words: Leakage reactance, Potier reactance, open-circuit curve, zero-power-factor curve

Abstract

Generator armature reactance represents the portion of machine flux that doesn’t link the filed and flux path mainly pass the air gaps and often is obtained from manufacturer data. In many old units in an existing power system, however, this parameter is not available. This is a common problem in Iranian Power system, where there are many generating units without any information from manufacturer on armature leakage reactance. This paper is a study on some Iranian Power plant units for estimating armature leakage reactance from Potier reactance calculation. Two cases was studied, one for units with available leakage reactance to determine the errors and other for units with no leakage available. Study showed this method is capable for estimating leakage reactance with acceptable errors.

52

98-F-ELM-560

Estimation of Synchronous Machine Parameters from the Results of Standstill Frequency Response Tests Using Vector Fitting M. Ghassemi, and S. M. Nabavi Department of Electrical Engineering, Tehran University, Tehran, Iran Key words: Frequency response tests, Parameter estimation, Vector fitting, Synchronous machine modeling.

Abstract

This paper presents a new technique to estimate of synchronous machine parameters. The proposed model uses results of Standstill Frequency Response (SSFR) tests as input data. Employing the well known Vector Fitting (VF) method, parameters of rotor components in qd-axes equivalent circuit are identified accurately. The VF will be demonstrated as an efficient and powerful method to approximate of frequency response of rotor components and to produce a reduced model of rotor section.

53

98-E-ELM-572

Simultaneous Application of EKF and RLS Methods for Induction Motor Speed and Parameters Estimation A. Zakipour

A. Vahedi

D.A.Khaburi

A.Gorbani*

Electrical Engineering Dep. Iran University of Science & Technology * Electrical Engineering Dep. Iran K.N.Toosi University Key words: Extended Kalman Filter (EKF), Recursive Least Square (RLS), Induction motor, Parameters estimation, Speed estimation

Abstract

In this paper the induction motor’s parameters and speed are estimated by the application of two methods. The Extended Kalman Filter (EKF) and Recursive Least Square (RLS) are used to implement the estimator. Composed of these algorithms has been investigated and the results are presented. The possibility of the application of these methods for on-line motor speed and parameter estimation for using in drive application has been analyzed. The theoretical development of algorithm is followed by simulation study which is used to illustrate the possible range of behavior including the introduction of noise and modeling errors.

54

98-F-ELM-593

Synchronous Generator Parameter Estimation Using Input Purposeful Stimulation Method Hamed Agahi Mahdi Karrari Electrical Engineering Faculty, Amirkabir University of Technology Key words: Input Purposeful Stimulation, Nonlinear system, Output feedback form, Parameter Estimation, Synchronous Generator

Abstract

Input Purposeful Stimulation Method uses the control input to actively drive the system state to points in the state space that allow the orthogonalized projection estimator to acquire all the necessary information about the unknown parameters in a finite time interval, whose maximum length can be computed. Therefore it is most suitable for online applications. The main feature of Input Purposeful Stimulation Method is that the study system should be transformed into an output-feedback form, in which the nonlinearities depend only on the measured output. To apply such a procedure to estimate the parameters of a synchronous generator, first, a third order nonlinear model with saturation is transformed to an output feedback form. Then the identification method is modified and applied to estimate the unknown parameters. The simulation results show very good accuracy of the estimated parameters.

55

98-F-ELM-594

Nonlinear Identification of Synchronous Generator Using Hammerstein Model Mahdiye Sadat Sadabadi, Mehdi Karrari, Maryam Sadat Akhavan Hejazi Electrical Engineering Department, Amirkabir University of Technology Tehran- Iran Key words: Synchronous Generator, Nonlinear Identification, Hammerstein Model, Piecewise Linear Map

Abstract

A new approach for identification of synchronous generator using Hammerstein model and with piecewise linear map is investigated in this paper. In this method, synchronous generator model consist of a lineardynamic block and a nonlinear-static block. The identification method simultaneously approximates these blocks. The proposed method is applied on a third order nonlinear model of a synchronous generator. In this study, the field voltage is considered as the input and the active output power and the terminal voltage are considered as the outputs of the synchronous generator. Simulation results show good accuracy of the identified model.

56

98-E-ELM-628

The Importance of Bandwidth, Noise Separation Method and Operating Conditions in On-line Partial Discharge (PD) Measurement on Large Turbo Generators E. Sharifi S. Amini Niroo Research Institue

K. Rahmani Neka Power Plant

Key words: Condition Assessment, Partial Discharge, Stator Insulation, Turbo Generators

Abstract

Diagnostic assessment of the insulation systems of large rotating machine is a concern of increasing priority to the electrical supply industries. Life extension and life assurance strategies for thermal stations have also increased the desire for determining the remaining life of machine insulation systems. For these purposes, on-line partial discharge measurement is one of the most important tests among all recommended online and off-line tests. Since this test is performed in real operating conditions, many considerations should be taken into account to have reliable diagnosis and avoid false assessment. In This paper, a practical experience in on-line PD test for a 440 MW hydrogen-water-cooled generator, including the results of some tests, analysis and some suggestions to do the test and analyze the data more effectively, are addressed. The paper also outlines the required specification for the PD detector particularly from sides of noise reduction, bandwidth and software.

57

98-F-ELM-630

Loss Minimization Using Optimal Flux Search Controller For the Field Oriented Controlled Induction Motor Drives Zamani.R Gholami.A Oraee.H “Sharif University of Tachnology” Key words: Induction Motor, Field Oriented Control, Loss Minimization, Searching Controller

Abstract

The growth of energy users while the energy sources are limited makes it necessary to investigate on methods to increase the efficiency of the systems. In this paper an optimal flux search controller for field oriented controlled induction motor drives is presented. This controller is designed in order to minimize losses in drive systems in light loads. The objective function for minimization process is the input power of the drive system. The flux refrence is determined through an optimal flux searching controller with adaptive steps to achieve fast dynamics and good steady state response. In the transient state a great flux step is used to speed up the convergence of searching algorithm and the step size is decreased in steady state to achieve a good response. Simulation results are presented to justify the performance of proposed approach.

58

98-F-ELM-665

Design and Manufacture of Thermoelectric Generator Babak Alinezhad , Farhad Alinezhad ,shabnam batebi, ghasem kavei Metallurgy Department of Engineering , semnan university – Aircraft Maintenance Engineering Department of Civil Aviation Technology College – Department of Physics , Sharif University – Research Center of Energy and Material.

Abstract

One of the last developments in electric power generation industry is the use of thermoelectric to generate electric power. for the first time in Iran thermoelectric generator was made of thermoelements by method of powder metallurgy.40 thermoelectric couples was assembled on two ceramic plates which has high electric conductivity .elements are made of two semiconductor types n and p of alloys Bi2Te3 − Bi2 Se3 and Bi2Te3 − Sb2Te3 . Totally less than 50 gr thermoelectric material was used in this little generator. Experiment results show that if there is a difference of 90 degrees between cold and hot plates, the output will be 1.1 V and 280mA. This little thermoelectric performance opens a shiny sight in front of wide use of these generator to generate safe and clean electric power in national electric power industry.

59

98-F-ELM-692

Estimation of Dynamic Parameters for Yazd Power Plant Synchronous Generator Using DC-Decay Test with Model Validation by Online Measurement E. Ghahremani 1,2

M. Karrari 1,2

M.B. Menhaj 1,2

P. Ansarimehr 1

1-Niroo Research Institute, 2- AmirKabir University Of Technology Tehran, Iran

Key words: Dynamic Parameters, Synchronous Generators, Estimation, DC-Decay Test Online Measurements, Validation

Abstract

In this paper, DC-Decay test procedure and implementation for estimation of a synchronous generator parameter in the gas units of Yazd power plant is presented. DC-Decay time domain data are acquired from standstill test measurements. The dynamic parameters are found by processing DC-Decay test signal. Then, online measurement procedure and acquired needful signal in generator working mode is described. At the end, the acquired dynamic parameter of Yazd power plant synchronous generator with DC-Decay test is validated by online measurement.

60

98-F-ELM-834

Effect of Geometrical and Rotational Speed on fatigue life of shaft and Stresses of rotor components of a 100 kW high Speed Micro generator M. Behrouz

Prof. R. A .Ghajar

S. Ziaee

Niru Research Institute - mechanic department Iran Key words: Micro generator, high-speed rotor, Strength and fatigue Analysis, magnification factor

Abstract

This paper presents analytical stress and fatigue analysis of a 100kW high speed radial flux cylindrical micro generator rotor. Then with the analysis method obtained and using magnification factors in a MATLAB code, effect of geometrical parameters and rotational speed on equivalent stresses and fatigue life safety factors of shaft sections have been determined. effect of location of axial holes and maximum radius of rotor on stress of retaining layer and compressive stress in magnets is being determined either.

61

98-E-ELM-858

COMPARISON OF ALTERNATIVE CONFIGURATIONS FOR A HIGH SPEED ALTERNAATOR FOR MICROTURBINES Mohammad Sadeghierad

Sohrab Amini

Saied Ziaie

Key words: High speed generator , Cylindrical type rotor, Disk type rotor, Design

Abstract

High speed machines are one type of electric machines that have application in high speed compressor, machine tools, energy storage systems, and particularly electric energy generation .The letter object that can be assessed by direct coupling of high speed generator (microgenerator)to shaft of a microturbine with speed rang of 50,000 to 150,000 r.p.m is due to select a special structure for microgenerator, so that, selection design analysis, and specially manufacturing of it would be very sensitive. Microgenerator mostly have disc and round rotor structure type and excite with rare earth permanent magnets (RMs) installed on the high speed rotor . In this paper after presentation the principal and general considerations for design, and analysis and results of some detailed designs, two intended structure analyzed based on feasibility study for manufacturing in the country , manufacturing technology , raw material and performance considerations, and finally one of these two types has selected for detailed design and prototyping.

62

98-F-ELM-876

Shahid Rajaee Synchronous Generator Parameters Estimation Based on SSFR Method M.R. Aghamohammadi1 M.A. Talebi1 M.R. Bank Tavakkoli2 M.R. Mohammadi Araghi2 H. Modaghegh2 1. Power and Water University of Technology 2. Iran Grid Management Company Iran

Key words: Synchronous Generator, Dynamic Parameters, SSFR, Genetic Algorithm

Abstract

Dynamic study of power system necessitates proper modeling of contributing elements. Synchronous generator is one of the most important elements of power system with a vast range of dynamic performance which requires precise modeling. Synchronous generator parameters identification based on machine Stand Still Frequency Response is a well known method that is documented by IEEE standard. In Iran, this method has been employed on the synchronous generator of the Shahid Rajaee power plant, for first time. In this paper, the results of application of SSFR method on the Shahid Rajaee power plant have been investigated. For processing the data obtained from SSFR tests and extracting generator parameters, an optimizing method based on genetic algorithm has been developed and proposed. Using the proposed algorithm, the parameters of the Shahid Rajaee power plant generator have been identified which show an acceptable comparison with the manufacture provided values.

63

98-F-ENV-164

Waste Management for BESAT Power Plant Amir Sohrabi Kashani, Zahra Delavar Moghaddam, Masoud Serpak Niroo Research Institute, Tehran Regional Electricity IRAN Key words: waste management, Besat power plant, wastewater recycle, treatment

Abstract

In the power plant and industries, we can recycle and reuse the wastewater by process improvement. The main parts of the solids in Besat thermal power plant are lime sludge that produced in water clarification and softening process. They have low toxicity, but enormous volume. The main objective of this paper is to propose some methods for waste management in this power plant. This project is supported by Tehran Regional Electricity, Niroo Research Institute and Besat power plant. The period of this study is July 2004 up to December 2005

64

98-F-ENV-212

Numerical study of effect of oxygen fraction on local entropy generation in a methane–air burner Mojtaba Borjali 1

Mohammad Javadi 2

1- Mashhad Generation Management Co 2- Ferdowsi university of mashhad IRAN Key words: Air–fuel combustion; local entropy generation; exergy; computational fluid dynamics Abstract

This study considers numerical simulation of the combustion of methane with air, including oxygen and nitrogen, in a burner and the numerical solution of local entropy generation rate due to high temperature and velocity gradients in the combustion chamber. The effects of equivalence ratio (φ) and oxygen percentage (γ ) on combustion and entropy generation rates are investigated for different φ (from 0·5 to 1·0) and γ values (from 10 to 30%). Combustion is simulated for the fuel mass flow rate resulting in the same heat transfer rate to the combustion chamber in each case. Numerical calculation of combustion is performed individually for all cases with the use of the Fluent CFD code. Furthermore, a computer program has been developed to calculate the volumetric entropy generation rate and the other thermodynamic parameters numerically by using the results of the calculations performed with the FLUENT code. The predictions show that the increase of φ (or the decrease of λ) significantly reduces the reaction rate levels. Average temperature in the combustion chamber increases by about 70 and 35% with increase of γ (from 10 to 30%) and φ (from 0·5 to 1·0) respectively. With increase of γ ,volumetric local entropy generation rate decreases. The ratio of the rates useful energy transfer to irreversibility therefore improves as the oxygen percentage increases. 65

98-F-ENV-429

Determining the costs of CO2 emission of thermal Power plants stacks on environment K.Feyzbakhsh-M.Ghiassedin-PhD. M.lotfalikhani matn.Co IRAN Key words: green house gases, CO2, environment, power plant

Abstract

Lots of efforts has been done for finding out the economics aspects of global warming in different parts of the world. Increasing of CO2 emission and the others green house gases and damaging of stratospheric ozone can increase global warming. Power plants by using fossil fuels for elctericity production emitting CO2 into the atmosphere. In this project that has been done in the Environmental Department of Matn Company, the costs of CO2 emission from a thermal power plant has been determined. By focusing on different kinds of fuel (heavy oil and natural gas) during low and high load production and consumptions, cost of CO2 emission has been calculated. In the minimum load the cost is 21.03 Rials per kWh and in maximum load it is 23.20 Rials per kWh. Current cost estimates from 15 to 87 US$/t CO2 for capturing the CO2 with an effect of 0.6-3.3 us cent per kWh and 5 to 20 US$/ton for transformation. According to the article six of kioto protocol the members who signed this protocol can trade green house gases amoung themselves if they produce more or loss than their quota.

66

98-F-ENV-810

Light Pollution Sayed Mohsen Banifatemeh South Kerman distribiution electrical company Iran Abstract

Light pollution is excess or obtrusive light created by humans. Among other effects, it causes adverse health effects, obscures stars to city dwellers, interferes with astronomical observatories, wastes energy and disrupts ecosystems. Light pollution can be construed to have two main branches: annoying light that intrudes on an otherwise natural or low light setting and excessive light, generally indoors, that leads to worker discomfort and adverse health effects. Since the early 1980s, a global dark-sky movement has emerged, with concerned people campaigning to reduce the amount of light pollution. Light pollution is a side effect of industrial civilization. It comes from sources such as building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and lit sporting venues. It is most severe in the highly industrialised, densely populated areas of the United States, Europe, and Japan, but even relatively small amounts of light can be noticed and create problems. With recent advances in private spaceflight, the prospect of space-based orbiting billboards appearing in the near future has provoked concern that such objects may become another form of light pollution. With this in mind, the United States Federal Aviation Administration sought permission, in May 2005, to enforce a law prohibiting "obtrusive" advertising in earth orbit. Similar intentions are yet to be expressed by authorities in most other countries, however. Types of light pollution

Light pollution is a broad term that refers to multiple problems, all of which are caused by inefficient, annoying or arguably unnecessary use of artificial light. Specific categories of light pollution include light trespass, overillumination, glare, clutter, and sky glow. It is common, however, for annoying or wasteful light to fit several of these categories. Consequences of light pollution

Energy waste Effects on human health and psychology Loss of safety Disruption of ecosystems 67

98-F-EPG-104

Design and optimization of a model combustion chamber for microturbine with finite volume method M. Tiourad1, S. S. Ziaee2, Maryam Seyedi3, Majid raufi rad4 Niroo Research Institute, Mechanical Systems Group Iran

Key words: Combustion chamber, pollution reduction, computational fluid dynamics, microturbine, optimization

Abstract

Recently, for several reasons in energy generation, like, tendency for energy loss reductions in distribution network, energy transitions and improve the safety factor of power generation, the distributed energy production has been significantly regarded. For this purpose, designing and manufacturing of microturbine in entire world have been expanded. A research project has been defined on the manufacturing and designing of mictoturbine in NRI. In present work the simulation of fluidics, thermal and pollutions in a combustion chamber for a practical microturbine have been carried out. For optimization of combustion and reduction of pollutants, the air delivery and the shape of combustion chamber have been modified. For increase the effectiveness of analyzes, the model for popular fuels like methane, butane, and gas oil have been carried out. Results have been presented for velocity, temperature, pressure and pollutants up to 20 different species in the combustion chamber. Finally a model has been introduced which shows acceptable agreement for microturbine on standard situation.

1. Author, Student of Sharif University of Technology 2. Project Manager 3. Co-Author 4. Project Supervisor

68

98-F-EPG-107

Off-Design Performance Analysis of 200kW Microturbine Ehsan Sadeghi1 Masoud Soltani Hoseini3

Saeed Ziaee Tabatabaee2 Mohsen Akbari4

Niroo Research Institute (NRI), Mechanical Systems Department Iran Key words: Microturbine, Off design, Characteristics Curve, Variable speed - Modeling Abstract

Microturbines almost work in off-design condition because of parameters such as variation of the ambient properties (temperature, pressure, etc.) and required power. Therefore, study the off-design performance of microturbines is very beneficial and necessary. In this paper, 200kW Capstone microturbine cycle is analyzed in the offdesign condition. For this purpose, characteristics curves of the microturbine components are required. In present study, regarding these curves, which have been obtained from experimental results, equations among air mass flow, rotation speed, pressure ratio, and turbine inlet temperature are developed. Considering these equations and design model of the cycle, each component is modeled in off-design condition. Considering this model, effect of varying inlet air temperature and power are analyzed and compared in fixed and variable rotation speed. Results show that increasing inlet air temperature from 15°C to 45°C, generated power and efficiency are reduced about 18% and 2%, respectively. Also, in 70% load, cycle efficiency is reduced 25% at fixed speed, but this amount becomes 4% at variable speed. 1. Research Engineer, NRI, Mechanical Systems Department 2. Microturbine Project Manager, , NRI, Mechanical Systems Department 3. Head of Power generation Institute, NRI 4. Research Engineer, NRI, Mechanical Systems Department

69

98-F-EPG-108

Effect of Intercooling on the Performance of Micro CHP Systems Ehsan Sadeghi1 Masoud Soltani Hoseini2 Mohsen Akbari3 Niroo Research Institute (NRI), Mechanical Systems Department Iran Key words: Microturbine, Intercooler, Combine Heat and Power Generation, Total Exergetic Efficiency, Bypass ratio Abstract

In recent years, the development of distributed power generation has resulted in significant reduction in network losses and transmission costs while increased reliability. Microturbine is one of these power generators that has the ability of relatively high power generation in spite of its small volume. In order to modify microturbine cycle characteristics, presentation and analysis of advanced configurations are important. Use of intercooling between compressors is one of these configurations. In this configuration, outlet air of the first compressor is cooled in the compact heat exchanger whit water and then entered the second compressor. In this paper, mentioned configuration is studied for various quantities of heat and power in CHP mode. In present study, each part of cycle is modeled exactly based on the first and second laws of thermodynamics. Considering these models, effects of varying parameters such as compressor pressure ratio, produced vapor pressure, and recuperator effectiveness on the main cycle characteristics are studied. Results show that increasing pressure ratio, power is increased compared to simple cycle. For example, this increase reaches 18% at pressure ratio of 5. Also, studied configuration has more efficiency and is a proper option for combined heat and power generation systems, especially at bypass ratios greater than 0.5.

1. Research Engineer, NRI, Mechanical Systems Department 2. Head of Power generation Institute, NRI 3. Research Engineer, NRI, Mechanical Systems Department

70

98-F-EPG-120

Case Studies on the Hydraulic Balance Effects of Electro-Boiler Feed Pumps on Hydromechanic Performance A. H. ASSEFINEJAD Master of mechanical engineering, Studies and planning office SABA POWER AND ELECTRICITY CO. (ZARGAN THER MAL POWER PLANT) IRAN

Key words: boiler feed pump, balance disk, axial hydraulic balance, axial clearance, FFT

Abstract

The effects of axial hydraulic balance on efficiency and vibration of boiler feed pumps (BFP) were studied in Zargan thermal power plant in Ahwaz. Rub and axial movement of balance disk led to an increase in vibration especially in radial directions. In some cases FFT shows that the dominant frequencies are not that of BFP operation. Besides, this experimental research shows that the monitoring of axial hydraulic balance, vibration and efficiency are three important factors to determine the best time of BFP overhaul, therefore the considerable cost reduction are concluded.

71

98-F-EPG-226

Life Prediction of Condenser Tubes Applying Fuzzy and ANN Algorithms A. Majidianb a

M.H. Saidi a*

Mechanical Engineering Department, Sharif University of Technology b Islamic Azad University, Science and Research Campus Iran

Key words: Life Prediction, Condenser Tube, Neural Network, Fuzzy logic

Abstract

The life prediction of thermal power plant components is necessary to avoid unexpected outages and to optimize maintenance tasks in periodic overhauls and to plan inspection tasks and their schedules for critical parts of power plant. One of the main critical components in a power plant is condenser because its failure can affect many other components which are positioned in downstream of condenser in the steam-water cycle. This paper deals with factors affecting life of condenser. Failure rates dependency vs. these factors has been investigated using Artificial Neural Network (ANN) and Fuzzy logic algorithms. These algorithms have shown their capabilities as dynamic tools to evaluate life prediction of power equipments. Results have been compared with the existing relevant data from the literature and collected data of the condenser tube failure of Neka power plant at north of Iran in order to determine the accuracy and verify the validity of the method.

72

98-F-EPG-290

Using fresh air in windbox repowering of existing team power plants V. Nayyeri khezrlou S. M. S. Mahmoudi Department of Mechanical Engineering University of Tabriz Tabriz-Iran Key words: steam power plant - gas turbine - windbox repowering

Abstract

Repowering is increasing efficiency and output power of an existing steam power plants by integration them with gas turbine. Several approaches are proposed for repowering regards to condition of existing power plants. One of those approaches which provides opportunity for existing boiler reusing is windbox repowering. In this method, one or several gas turbines are installed near the existing steam unit and the exhaust of gas turbines is used as preheated combustion air for boiler. The main difficulty in integration of gas turbine and boiler is decreasing flame temperature in supplementary combustion of boiler due to low oxygen content of gas turbine exhaust compared with fresh air and its effect on heat transfer process especially in radiative sections. When advanced gas turbines are used in windbox repowering, the fresh air should be used for increasing oxygen due to low oxygen percent. In this study, the effect of using fresh air in wind box repowering will be investigated and two main arrangements, preheating and not preheating of fresh air will be compared.

73

98-F-EPG-455

Numerical studies of heat transfer and flow between rotating coaxial cylinders M.Akbari, S Ziaee, E. Sadeghi NRI, Power generation Institute, Mechanical group Iran Key words: Coaxial cylinders, Heat Transfer, Pressure drop, Turbulent flow

Abstract

A numerical study has been performed for the flow and heat transfer in the space between a pair of coaxial cylinders with the outer one fixed and the inner one rotating. In this work, rotational speed of inner cylinder varies from 1000 to 3000 rpm for low speeds and from 10000 to 60000 for high speeds. k-ω and RSM models were used for modeling of turbulent flow in the numerical domain. Flow was considered to be compressible for pressure drop calculations and incompressible and fully developed for heat transfer. Comparison with experimental results for low speed condition shows good agreement for axial, azimuthal velocity and skin friction factor.

74

98-F-EPG-656

Simulation and optimization of cogeneration systems using intelligent systems R. Fazeli1 , M. Boroushaki2 School of Mechanical Engineering, Sharif University of Technology Tehran, Iran Key words: Artificial neural networks, optimization of cogeneration system, Genetic Algorithm

Abstract

Cogeneration is a kind of combined thermodynamic cycles, in which a gas turbine is used for steam and power production. In today's world, because of limitations on natural energy resources and increasing energy demand the effective design of energy systems is essential. In the optimization of complex energy systems (i.e., power plants), the thermodynamic optimization aims to minimize the thermodynamic inefficiencies: exergy destruction and exergy losses that it obtains by fuel mass flow minimization. This research presents the application of neural networks and genetic algorithms for simulation and optimization of a cogeneration system, while training data were prepared by a simulator. The steady state behavior of system is simulated by Multilayer Feedforward Neural Network. Results of static net have excellence agreement with simulator data. Optimization results according to decrease the thermodynamic inefficiencies were discussed.

1. Graduate Student 2. Assistant Professor

75

98-F-EPG-670

Considering Daily Fuel Constraints in Optimal Load Dispatch between Blocks of a Combined Cycle Power Plant Mustafa Rajabi Mashhadi

Habib Rajabi Mashhadi

PHD student -ferdowsi university of mashhad And electricity market office in Khorasan region electric company

assistant professor ferdowsi university of mashhad

Key words: Fuel constraint, dispatch, combined cycle units, Genetic algorithm, generation scheduling

Abstract

Considering daily fuel constraints, the optimal load dispatch between blocks of a combined cycle power plant is studied and analyzed in this paper. According to this constraint which is occurred each year in winter, Tavanir Company computes and assigns shares of liquid & gas fuel for relevant power plants. In addition to this external fuel constraint, some internal fuel constraints should also be considered in operation of a power plant. Possibilities of changing fuel type or using a mixed fuel which depend on the power plant technology are some examples of the internal fuel constraints. In this paper both external and internal fuel constraints are formulated in the above mentioned optimal load dispatch problem. Since the cost curve of a combined cycle unit is not a convex function and its corresponding incremental cost curve is not monotonously increasing, the optimal dispatch problem will be a non-convex optimization problem. To solve this complex optimization problem, a genetic based solution approach is developed. The obtained results show that the optimal load dispatch between the blocks is strongly affected by the internal & external fuel constraints. Furthermore, it is shown in maximizing power plant owner's profit that the fuel constraints play an important role in offering price to the spot market. 76

98-F-EPG-729

MAXIMIZATION OF MOMENTUM FLUX AT EXIT OF NOZZLE BLADES OF A TURBINE BY GENETIC ALGORITHM A.R. Teymourtash1

M.R. Mahpaykar2

K.Hadad3

MINISTRY OF ENERGY Central Research Board of Khorasan Region IRAN Key words: Genetic algorithm, Nozzle blade, Optimized, Momentum flux, Aerodynamic losses

Abstract

In this study an optimized profile for a nozzle blade of a turbine is carried out by using genetic algorithm; Two objective functions are used: Maximization of the exit momentum flux and minimization of aerodynamic losses. For calculating the flow parameters, steady blade – to – blade solutions for compressible flow are obtained by the fourth order Rung – Kutta time marching scheme; This method is fully explicit and is applied to the Euler's equations in the finite volume conservation law form.

1. Assistant Professor (Department of Mechanical Engineering, Ferdowsi University of Mashhad) 2. Associated Professor (Department of Mechanical Engineering, Ferdowsi University of Mashhad) 3. M.Sc student

77

98-F-EPG-730

SIMULATION OF AERODYNAMIC SHOCKS IN A CASCADE OF TURBINE BLADING USING AN ADAPTIVE GRID ON REAL TRAILING EDGE BOUNDARIES A.R. Teymourtash1

M.R. Mahpaykar2

K.Hadad3

MINISTRY OF ENERGY Central Research Board of Khorasan Region IRAN Key words: Turbine blade, Jameson, Euler, Adaptive grid, Shock, Cell center

Abstract

Simulation of aerodynamic shocks in a cascade of turbine blading is obtained using the Jameson's time marching scheme based on a cell-center formulation. This method is fully explicit and is applied to the Euler's equations in the finite volume, conservation law form. The present study focuses on other important numerical aspect such as treating the periodic boundaries downstream of the trailing edge in the case of discontinuity of the flow due to presence of a passage shock, for this purpose the movement of the streamline at down stream of the calculating point included in the solution. In order to determine the ability of this study, steady blade-toblade solutions are obtained for turbine cascade under transonic flow conditions and compared with measurements.

1. Assistant Professor (Department of Mechanical Engineering, Ferdowsi University of Mashhad) 2. Associated Professor (Department of Mechanical Engineering, Ferdowsi University of Mashhad) 3. M.Sc student

78

98-F-EPG-731

Research on causes of breakdown in welded joints of supper heater pipes at tous power station M.Kahrom, Associate professor, Ferdowsi University of Mashhad. S.A.Sajadie, Assistant professor, Ferdowsi University of Mashhad Gh. Bahadorie, Toos Power Plan Production Co. M.Mahdiezadeh, Postgraduate research assistance Key words: Header,Superheater, Thermal stresses Abstract

Supper heaters and reheater headers that tolerate high pressure and temperature are two important equipments in the boiler. One of common damages in header is cracking in the welded joints of connected pipes to the header. At first glance it looks like these cracks are produced by fatigue and creeping mechanisms. On the other hand Thermal stress was taken as possible cause. To study the cause of failure present project was defined. At the first step, the micro structure tests on the location of damage has performed the results of these tests showed that micro structure of metal at the faulty locations were normal. On second step, assistance taken from simulation software’s predicting thermal stresses due to relative movements of pipes and amplitude due to expansion and contraction of header in the variety of directions was studied. From this study we concluded that the header could not expand completely in the direction as connected pipes are expanding. As a result this causes excess concentration of stress on joint points on welding of connected pipes and results in cracks in weddings. Measurement shows that the local expansion of header is in its longitudinal direction and perpendicular to it. More over in special conditions of temperature and pressure during start up of unit, two ends of header moved downward and its middle point moved upward. Calculations and evolutions shows that, downward movement of two ends of header due to Design failure cause increasing stress level in the welding of connected pipes to the header and consequently accelerate cracking in the welding of connected pipes to both end of header. Upward movement in middle of header has little effect on the stress level of middle pipes. So this matter and complete expansion of pipes that are connected to the middle of header (according to the local measurements) form the main reasons of no cracking in the pipes connected to the middle of header. Practical solution that has recommended for preventing from cracks, are including to removing the expansion barriers and preventing from downward movement of both ends of the header. 79

98-F-EPG-739

Analysis of Correlations between Measurements for Gas Turbine of QOM power plant M. S. AGHIGHI Bu-Ali Sina University IRAN

E. GHARIBIAN N.R.I IRAN

Abstract

The important thing that should be checked in gas turbine is whether any of the gas-path measurements chosen respond in similar ways to other measurements to all (or nearly all) of the component changes. This test indicates whether there is any redundancy between the measurements. This may be beneficial if the measurements are present for reasons other than performance analysis, but may be an indication of over-specification of required measurements if the analyst is trying to determine an optimum set of measurements for analysis in the future. in this paper correlation between measurements of qom gas turbine power plant has been studied.

80

98-F-EPG-820

Performance analysis journal bearings without dimension limiting With Reynolds equation numerical solution Hassan Akbarzadeh-Mahmood Hosseini-Esmaeil Ramazani Khorasan region electric Co. Khorasan gas power plants production management Co.

Key words: Journal bearing, Reynolds equation, GMRes1 Method

Abstract

In the most books which talk about behavior of journal bearings completely has been analyzed in theory conditions. Which the bearing is analyzed with special ratio of length to width, for example L/D>2 and L/D) and over-rate-of-change (dI/dt)>. Suitable settings of threshold levels are very essential in appropriate operating and prevent malfunction of fault indicators. Design and implementation of a prototype operating based on this method are introduced.

130

98-F-PDS-695

Modulation Of DC Railway System For Stray Current And Rail Touch Voltage Control A.Gholami1

M.Niasati1, 2

S.Mozouni3

1. Department of Electrical Engineering, University of Science & Technology, Iran 2. Department of Engineering, University of Semnan, Iran 3. Department of Engineering, University of Azad Tehran-markaz Tehran, Iran

Key words: DC electrified railways, stray current, rail touch voltage, earthing system

Abstract

In DC rail transit systems, the running rails are usually used as the return conductor for traction current. This arrangement mainly focuses on economic considerations, since it does not require the installation of an additional return conductor. Low resistance between the traction return rails and the ground allows a significant part of the return current to leak into the ground. This is normally referred to as leakage current or stray current. The amount of leaking current depends on the conductance of the return tracks compared to the soil; and on the quality of the insulation between the tracks and soil. The stray currents represent serious problems for any electrified rail transit system. The corrosion problem has been a major concern to the railway and other parties involved since the early days of DC railways. This paper presents the electrical model of DC railway system for simulation and calculation the effective factors on the stray current and rail touch voltage amplitudes. Results of simulations show that stray current can be reduced by reducing the resistance of the running rail, increasing the insulating resistance of the rail and the earth, shortening a distance between substations and etc.

131

98-F-PDS-709

A Control Algorithm for Thyristor-Switched Arrester to Improve Transient States of Capacitor Switching in Distribution Network K.Gorgani Firouzjah , A.Sheikh-Al-Eslami , S.Lesan Faculty of electrical Engineering Mazandaran University Babol-Iran

Key words: Switching of Capacitor, Transient State, Arrester, Thyristor Switch

Abstract

Parallel capacitors are used in distribution networks as compensator elements which are utilized at substation and consumer sides. Most common events in distribution networks are transient states and over voltages due to switching of capacitors. In this paper, the effects of transient states due to switching of substation side capacitor on power factor correction capacitor at consumer side are analyzed. Simulation results show that the most common factor in transient state time and over voltages peak is the consumer side power factor correction capacitor. This paper presents a control algorithm using power electronic devices to suppress over voltages of capacitor switching. With compare to traditional methods, this method utilizes arresters with maximum continuous operation voltage (MCOV) equal or lower than nominal voltage that can switch to the network with thyristor switches. This method is more capable than conventional control methods to suppress the over voltages and decrease transient states time (up to one cycle) and also improve the consumer power quality. Theoretical analysis and simulation results with MATLAB and EMTP are presented to analyze proposed method.

132

98-F-PDS-728

High Energy & Power Losses in The Distribution System, An Old Deficiency in The Iranian Power System Ahmad Ali Bahmanpour Noorgostar Consulting Engineers Co.

Key words: Energy & Power Losses, Lots of Distribution Transformers and No Secondaries

Abstract

The causes for high energy & power losses in our power distribution system (that is 16.6% energy losses and about 23.3% power losses) and the reasons why these losses in power distribution system are being ever lasting have been discussed in this paper. In addition to the technical and electrical causes for the increasing per cent of losses, besides the factors such as the difficulties of its measurement, the solutions such as lots of distribution transformers and no secondaries, the effects of promotion of medium voltage in the loss reduction etc. have been studied. The proper methodology of such studies, not usually followed in the local research papers, is emphasized. Moreover, it is mentioned that solving this huge problem is in need of such high amounts of money and mental & physical work that both the decision makers and the executers should bear in mind firstly not expecting immediate results and secondly not losing hope for not obtaining noticeably immediate results. The paper is concluded with the section titled “What shall be done” and 3 appendices.

133

98-F-PDS-745

Fault Analysis in Unbalanced Distribution Networks With Earth return R.Ebrahimi S.Jamali A.Babaei Iran University Science and Technology Iran Key words: Series impedance of overhead lines, Unbalanced distribution networks, unsymmetrical faults, short-circuit current

Abstract

The short-circuit currents are very important quantity affecting the design of bus systems, grounding systems, circuit breakers, substation apparatus, rotating machines and in fact, almost all the aspects of distribution system design. Among those applications, a robust and efficient short-circuitanalysis program is very important for planning and operation of systems. In this paper, a fast and easy programmable short circuit analysis method for unbalanced distribution systems is proposed. Two relationship matrices, the bus-current-injection-to-branch-current matrix are used to represent the special topological characteristics of distribution networks. The proposed short-circuit analysis method is developed from these two matrices and can be used to solve the various types of unsymmetrical faults. Therefore, a computer program by Matlab software has been developed to calculate the short circuit current of unbalanced distribution networks. Simulation results obtained using the proposed technique and a fictitious network (similar to Iran distribution networks) will be presented.

134

98-F-PDS-773

Fuzzy Load Flow in Radial Distribution Systems with Considering Load Uncertainty Belal Mohammadi kalesar Msc.Eng.Student Department of Electrical Engineering Shiraz University

AliReza Seifi Assistant Professor Department of Electrical Engineering Shiraz University

Key words: Radial Distribution Systems, Uncertainty, Fuzzy Numbers

Abstract

This paper presents a fuzzy approach for radial distribution systems. Fuzzy set theory proposes an appropriate way to model inexactly expressed information and data which have uncertainty. In this paper the combination of fuzzy models and techniques for electrical distribution systems was presented. The theories relating to the fuzzy numbers are simplified into a form suitable for practical application. The utilization of fuzzy approach is demonstrated by a radial load flow method where the voltage in the substation and the power demands are represented by fuzzy numbers. The comparison of using this method with previous methods is brought and is simulated on a 34-bus radial distribution test system and results are investigated.

135

98-F-PDS-836

Insulator Leakage Current Monitoring in Hormozgan Regional Test Station in South of IRAN M. Rezaei1 , A. R .Moradian1, M. R. Shariati1 M.Vafakish1, F.Nasri1, and S.Ghasemi2 1-Niroo Research Institute 2- Hormozgan Regional Electric Company IRAN

Key words: Leakage current, insulator, Pollution, research site, Environmental conditions Abstract

According to DIN50019, the coastal districts of Persian Gulf are classified as extreme hygrothermal climatic zone. Unusually high saturation vapor pressure up to 53 mbar observed in this zone, justify this marking, as such air humidity phenomena are unique in the free atmosphere of the earth and are absolute extremes .intensive night falls of dew, which can occur regularly for several months, and long periods of rainless and sultry weather, worsening the situation for T & D system. In such a corrosive and polluted region, system reliability and maintenance cost are the major concerns of utility companies. Therefore the selection of the correct type of electrical equipments is thus most important to ensure a secure supply but, unfortunately, the testing of equipments in order to identify those designs which will provide satisfactory long term performance for a particular application is no easy task. The validity of laboratory tests is thus often questioned as the procedures adopted may not take into account significant factors which would be encountered in service or they may over-emphasis others. In view of the above, the evaluation of equipment in naturally polluted outdoor test stations is becoming more popular. Although involving a longer test duration, and still requiring care in the correct interpretation of the test data, the results tend to be accepted with more confidence This Test station is equipped with comprehensive instrumentation for detailed leakage current and meteorological data analysis. In this paper executive activity of the leakage current monitoring of different distribution insulator profiles is presented. 136

98-F-PQA-142

Power Quality Improvement in Radial Power Distribution Networks With Controllable series compensator and Comparision of Different Controllers R.Seyedi Moshanir Co. Iran

S.Lesan A.Sheikeslami Mazandaran University Iran

F.Razavi Amirkabir University Iran

Key words: Power Quality, Series Compensation PI Controller, Fuzzy Logic, GCSC Abstract

In this research after mentioning theories and applications of fixed and controlable series capacitive compensation in radial power distribution networks, mentioned guidelines for improvement of power quality for radial power distribution networks that have ( XR > 1) and feed large and variable or fixed loads that it was usage of GCSC1 system. Upgrading Aghajari NGL200 manufacture was chosen for case study in this research. Because of various problems in operation and maintenance of Aghajari NGL200 Gas compressor drive that it is Gas turbine now, were proposed High voltage Asynchronous squirrel cage motor instead of Gas turbine for Gas compressor drive. Application of GCSC system was improved power quality and voltage drop of this situation. Simulation of this power electrical system was done with well-known PSCAD software. PI compensator and Fuzzy Logic system were used for controlling the GTO2's gate pulses and performed the comparison between them and direct motor starting. Because of controllability of GCSC system, designer can select series capacitor value equal to total inductive value of radial power distribution network. In this case, these power distribution networks don't have any resonance or ferroresonance phenomena. At last some proposals for designing and upgrading radial power distribution networks in Iran were mentioned. 1. GTO Controlled Series Capacitor 2. Gate Turn Off Thyristor

137

98-F-PQA-148

Design and Manufacturing a 3-phases PWM Rectifier with current link and unity power factor using vector control Ahad Kazemi, Abdorreza rahmati. Mohammad Arasteh Iran university of science and technology Key words: rectifier with current link, SVM, power factor

Abstract

Input LC filter is utilized to filter harmonics of the carrier frequency. SVM compensates undesired pahse-shifting due to input filter.Unity power factor is achieved by lagging the input current of the PWM rectifier with respect to the source voltage. With a novel hardware design, we could use 8-bit microcontroller to achieve a high performance PWM rectifier. Simulations in MATLAB show the better performance with respect to six-step rectifier. Practical results on a 10kW,110V prototype shows that the proposed scheme gives good performance for the PWM rectifier.

138

98-F-PQA-161

An Algorithm to Design Double Tuned Filters Based on Power Factor Correction for HVDC Systems M.Joorabian

S.GH.Seyfossadat

M.A.Zamani

Shahid Chamran University of Ahvaz

Shahid Chamran University of Ahvaz

Islamic Azad University of Mahshahr

Key words: Double Tuned Filter, Harmonics, Power Factor Correction, HVDC Converters

Abstract

This paper presents a study of passive double tuned filter design to reduce harmonic distortion caused by harmonic sources and compensate power factor in electrical systems. On the basis analyzing the characteristics of the basic type of double tuned filter, an algorithm for precisely determining its parameters is presented here. Using this method, the inductances and the capacitances of the damped-type double tuned filter can be calculated from the known data such as the reactive compensation capacity, the tuned frequency and the parallel resonant frequency, etc. The proposed method is used for harmonic reduction in AC side of a six pulse HVDC converter. The system has been simulated with MATLAB and simulation results clearly show the proper operation of designed filters.

139

98-F-PQA-262

Design and Implementation of a Static Var Compensator (6.6kV/±1kVar) G.Dehnavi, S.Heidari, A.Sadeghzadeh Niroo Research Institute Iran Key words: SVC, TCR, Distribution Networks

Abstract

There are many industrial loads in distribution networks that consume large amount of active and reactive power capriciously. This results in decreasing power quality indexes, the effect of which is a lot of damage to electrical appliances or lack of power supply due to protection system performance. In order to compensate for destructive impacts of such loads the best solution is SVC installation. This will bring about voltage flicker removal along with power factor correction as well as load balance in three phases. The paper presents design and construction of a TCR type SVC the capacity of which is ±1MVar and it is connected to 20kV feeder through a step-up transformer. The SVC working voltage is 6.6kV. Current filters eliminate harmonics due to TCR. Control and monitoring systems are based on two individual PCs. Monitoring system displays current and voltage signals and it is used for start-up and shut-down of the system as well. The voltage and power are chosen so that the system is applicable for installation in 20kV / 5MVA passage substations and also for compensating the destructive effects of ≈5MVA industrial factories on voltage (both in 20kV and in 6.6kV bus). This scheme was fulfilled for the first time in Iran with more than 95% domestic components. The expense of overseas purchase of a similar SVC is much more than that of domestic accomplishment of this project (about twice this price) plus the expenses of transportation and installation. 140

98-F-PQA-319

Detection and Classification of Power Quality Disturbance With Wavelet Transform and Neural Networks Javad Rouhi Reza Ghaderi Saeid Nejati University of Mazandaran (Noushirvani Institute of Technology, Faculty of Electrical Engineering) Iran Key words: Power Quality, Discrete Wavelet Transform, Neural Networks

Abstract

In this paper, a neural network classifier based on the discrete wavelet transform (DWT) is used to classify the type of power quality (PQ) disturbances is presented. Using the DWT with the multi-resolution signal decomposition (MSD), the power disturbance characteristics can be transferred into the time-frequency domain. The energy of the signal decomposed to frequency subbands can be used to extract feature parameters for classifying various disturbances. The proposed classifier has been designed to use five feature parameters that obtained from discrete wavelet transform, and an auxiliary parameter determined by the rms value. The proposed classifier shows good performance and efficiency for different types of PQ events and disturbances defined in IEEE and IEC. The results of comparison between this method and the state of the art techniques in this connection are presented in this report as well.

141

98-F-PQA-337

The Improvement of SSSC and SVC performance in reducing oscillation amplitude of transition state with suitable control signal suggestion based on lyapunov stability criterion Tehran, Iran

Abstract

SSSC,as a series synchron compensator ,and SVC,as a reactive power shunt compensator,play a great role in the increase of system stability. In this paper, we offered a non_linear signal to adjust injection voltage by SSSC and applied susceptance by SVC ,the selection of which was based on lyapunov criterion. Having done the simulation on SVC and SSSC ,we compared the improvement of compensator system performance in damping the vibrations whit the result of using linear and non linear control signals and showed the improvement of suggested method performance using the combinational control methods(continuous and non-continuous ) is another experiment in which we consider maximum susceptance value for SVC in first oscillation of capacitor susceptance minimum condition from the first condition of capacitor susceptance maximum,having reached the maximum rotor angle and the speed zero ,of course we applied this method in simulating SVC.[9]

142

98-F-PQA-450

Design of an Artificial System for Detection of Direction of Short Duration Voltage Events in Power System and Evaluation of Event Standard Index A. Farrokh Payam1, B. Mirzaeian2, M. Moallem1,3 1. Isfahan, EPRAD Company 2. University of Isfahan 3. Isfahan University of Technology

Key words: Sag,Swell, Voltage-Current Profile, Event Direction

Abstract

In this paper an artificial system for the detection of direction of short duration voltage events is presented. Short duration power quality events such as sag, swell and interruption are the most important power quality problems in power system, that cause high financial losses in industrial and commercial sections. For these reasons the importance of determination of the direction of these events is the subject of interest of many researchers. In the proposed method, based on simulation and field tests, for the purpose of detection of direction of disturbance with respect to measurement point the slope voltage-current profile is presented. Computer simulations and field tests demonstrate the validity and accurate performance of the proposed method.

143

98-E-PQA-494

Improving of Power Quality in Distribution Systems With UPQC Under Non-Linear Load Condition and distorted source Reza Rahnavard1, 2

Seyed Hossein Hosseini 1

1. Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz, Iran. 2. Azarbyjan Regional Electric Power Company, Tabriz, Iran.

Key words: Power quality, Unified power quality conditioner

Abstract

This paper discusses the application of unified power quality conditioner (UPQC) for improving power quality of a system supplying non-linear and induction motor loads. Unified power quality conditioner is one of the major custom power solutions that is capable of mitigating the effect of supply voltage sag at the load end or the point of common coupling. It also prevents load current harmonics from entering the utility and corrects the input power factor of the load. The UPQC can compensate for current and voltage harmonics and also for reactive power. Simulated results show the ability of the proposed method to obtain the harmonic contents of voltage and current, independently of one each other.

144

98-F-PQA-523

Active Filter Control Method Based on Virtual Flux and twelve sectors SVM Abdolreza Rahmati, Adib Abrishamifar and Ebrahim Abiri Iran University of Science and Technology (IUST) IRAN Key words: active filter, DPC, power quality, harmonics

Abstract

Active filters have proven to be more effective than passive techniques in solving harmonic and power factor problems. This paper proposes a control scheme based on the instantaneous active and reactive power (DPC). The inverter of this active filter is a three-phase, two-level converter. Conventional carrier or space vector techniques are used as modulators and pattern generators for the Pulse Width Modulated (PWM) converter. Virtual flux and a PLL based on a synchronous double reference frame (SDRF-PLL) cause this control system be resistant to majority of the line voltage disturbances. Good dynamic response, independent control of active and reactive powers and also unity power factor of converter are advantages of this method.

145

98-F-PQA-532

Analysis of D-STATCOM and DVR Operation for Voltage Control in Distribution Networks with a New Control Strategy H. Hatami and S. H. Hosseini Faculty of Electrical and Computer Engineering, University of Tabriz Key words: PSCAD/EMTDC, D-STATCOM, DVR, Sinusoidal PWM, VSC

Abstract

This paper addresses the issue of modeling and analysis of custom power controllers, a new generation of power electronics-based equipment aimed at enhancing the reliability and quality of power flows in low-voltage distribution networks. A new PWM-based control scheme has been proposed that only requires voltage measurements and no reactive power measurements are required. The operation of proposed control method is presented for the following two custom power controllers: the distribution static compensator (D-STATCOM) and the dynamic voltage restorer (DVR). Simulations and analysis were carried out in PSCAD/EMTDC with this control method for two proposed systems. The reliability and robustness of the control scheme in the system response to the voltage disturbances due to system faults or load variations is clearly shown in the simulation results.

146

98-F-PQA-534

Charge Balance Control Method for Symmetrical Multilevel Inverters Based UPQC Ebrahim Babaei, Ghasem Ahrabian, Ghasem Alizadeh and Seyed Hossein Hosseini Faculty of Electrical and Computer Engineering, Tabriz University Tabriz, IRAN

Key words: Multilevel Inverters, FACTS Devices, UPQC, Power Quality, PWM

Abstract

The switching strategies for multilevel inverters have typically focused on synthesizing a desired set of three phase sinusoidal voltage/current waveforms using several DC voltage/current levels. This results in the DC bus terminals to become unbalanced and hence causing the net power drawn from the multiple DC bus terminals to be unmatched and time-variant. In this paper, two methods that are capable of balancing the DC voltage/current sources in a cascade multilevel inverter introduced. The simulation results verify how to implement this strategy in order to maintain equal charge/discharge rates from the DC sources in a cascade multilevel converter. Next we are going to present a unified power quality conditioner (UPQC) based on multilevel inverters, for which this method eliminates transformers that are being used in the conventional UPQC. The main purpose is to compensate for supply voltage and load current imperfections, such as sags, swells, interruptions, imbalance, flicker, harmonics and current unbalance. The result is excellent conditioning performance of the proposed UPQC for resolving the power quality problems.

147

98-F-PQA-535

Introduction to a half bridge high frequency PWM controlled soft switching inverter for induction heating Ali Yazdanpanah Goharrizy

Seyyed Hossein Hosseini

Faculty of Electrical and Computer Engineering ,University of Tabriz, Tabriz, Iran

Key words: induction heating systems, half bridge inverter, PWM control strategy

Abstract

Conventional half-bridge high frequency inverters due to their simplicity and controllability achieved many industrial and domestic implementations. In order to achieve soft switching condition output power rang would be limited particularly, if PWM control strategy is used. To solve this problem an inverter with new topology is proposed. This paper proposes a new halfbridge high frequency inverter which is complement with an active quasiresonant snubber. This inverter is designed according to conventional halfbridge high frequency inverters structure and continuously output power control by using PWM control strategy is obtained. Soft switching region of the proposed half-bridge inverter is extended, relative to conventional halfbridge inverters. Uses can include a home cooking application with a high thermal efficiency at a fixed frequency of 20 kHz. Simulation results show the superiority of the proposed inverter at different operation condition.

148

98-F-PQA-603

A New Method based on Using the THD of Phase Currents for Detecting the Islanded Networks by Wind Turbines Hossein Kazemi Karegar

Abdolreza Shataei

Academic staff of Zanjan University

Post Graduated Student

Electrical Engineering Department Zanjan University Zanjan-Iran

Key words: Islanded Networks, Wind Turbines, Wind Farms, THD

Abstract

In this paper, a new method based on THD of phase currents will be presented in order to detect islanded networks by wind turbines. The method measures the THD of phase currents and comprises its magnitude with maximum and minimum values. If the measured value does not be with in the range, then the network is islanded. The proposed method verified by applying it on a real wind farm in a real network. The used wind turbine is V47 660 kW Vestas in Manjil wind farms and the network is Manjil distribution network.

149

98-F-PQA-624

Development of a New Algorithm for Estimation of Location, magnitude, and Type of Harmonic Sources in Power Systems A. Saffarian

S.H. Hosseinian

Electrical and Computer Engineering Dept. University of Tehran Tehran, Iran

Electrical Engineering Dept. Amirkabir University of Technology Tehran, Iran

Key words: Harmonic state estimation, harmonic source, measurement equations, singular value decomposition

Abstract

This paper develops a new algorithm for harmonic state estimation (HSE) of three phase asymmetrical power systems. This algorithm contains a new procedure for computation of admittance matrices in HSE and a new procedure for reduction of measurement equations. This algorithm uses singular value decomposition (SVD) approach which eliminates numerical instabilities in the solution HSE. This approach enables harmonic state estimation to be performed in both fully observable and partially observable networks using a few harmonic measurements. Using this approach location, magnitude, and type of harmonic sources can be estimated accurately. The proposed algorithm increases convergence rate, accuracy and efficiency of HSE through reduction of additional matrix calculations, enhancement of result's accuracy, and elimination of the need to do observability analysis prior to state estimation. The new algorithm has been tested in a real network with promising results.

150

98-F-PQA-626

Mitigation of Voltage Dip in Parallel Loads and DG Resources without Using Custom Power Devices M. Mahmoodi G. B. Gharehpetian M. Abedi R. Noroozian Electrical Engineering Department, Amirkabir University of Technology Tehran, Iran

Key words: Voltage Dip, Distributed Generation, DC Distribution System, Utility Converter

Abstract

Voltage Dip is one of the main power quality issues in AC distribution networks and results in miss- operation of loads and Distributed Generation (DG) resources. Uninterruptible Power Supply (UPS) and Dynamic Voltage Restorer (DVR) systems have been proposed to overcome this problem in AC distribution networks. The increasing presence of DC power in modern DG resources, sensitive loads and electric motor drives has made DC distribution systems preferable over AC networks from economical, technical and reliability points of view. In order to reduce the effects of AC network on DC distribution system devices, Energy Storage System (ESS) has been proposed by Electric Power Research Institute (EPRI) and other previous researches. ESS resources have several problems and limitations. In this paper, a suitable control strategy is suggested for utility converters interfacing the AC network with DC distribution system. The proposed control strategy results in cancellation of AC voltage dip effect on loads and DG resources in DC distribution systems without using ESS. The priority and effectiveness of the proposed system is verified by simulation results and their comparison with mathematical equations and previous researches.

151

98-E-PQA-705

Twin Inverter Topology for Shunt Active Power Filters Mohsen Mesbah

Iman Sadinezhad

Iran University of science and Technology

Chamran Universitry

Key words: Shunt Active Power Filter, Twin Inverter

Abstract

this paper presents a new Inverter topology (abbreviated as Twin inverter) for Inverter base shunt active power filters. This topology has the advantage of more controllability and faster response due to rapid changes in direction of inverter current. Unlike the conventional topologies, this new topology operates in continuous conduction mode which helps the designer to select higher values for inductors in order to have smaller ripple current without any appalling effect on system performance. This topology shows smaller current spikes and then lowers THD due to rapid changes in direction of inverter current. Another advantage of this topology compare with traditional topology is that both switches for each branch can be turned on at the same time which makes this opportunity to have separate control loops for each switch. The simulation results confirm the mentioned advantages for Twin inverter topology.

152

98-F-PQA-861

Harmonic Study of Kerman Tire Complex Electric Network and Recommended Measures for Harmonic Reduction D.Ebadi

S.H.Fathi

Mahshahr Azad University IRAN

Amirkabir University IRAN

Key words: Electrical Drives, Harmonic Standard Limits, Harmonic, 12Pulse Converter, harmonic Filter

Abstract

In this paper, the electric network of Kerman tire complex is studied and some appropriate recommendations for harmonic reduction are presented. The most significant harmonic sources are electric drives, discharge lamps and battery chargers. Among these nonlinear loads, electric drives play the main role. The measured results show that harmonic spectrum of the drive currents are beyond the IEEE standard. Unbalanced firing angles of the converters and unbalanced distribution of the single phase rectifiers, supplying the field windings of the dc drives, between three phases are additional causes which increase harmonics as well as the three phase unbalance. The measurements carried out by harmonic analyzer and compared with national standards show that current THD at PCC is considerably high and with the future developments in the production lines it will certainly exceed the standard level. Therefore, adjustment of firing angles, balanced distribution of single phase rectifiers, re-tuning of the existing harmonic filters as well as installation of new filters are recommended.

153

98-E-PQA-899

Modeling and Control of an Electric Arc Furnace Mohammad Hejri, Mohammad Mobed Sharif University of Technology Iran

Key words: Electric Arc Furnace (EAF), Electrode positioning system, Power quality

Abstract

Because Electric Arc Furnace (EAF) is one of the biggest energy consumers in the steel plants and also could cause harmonic and flickering effects back to the network utility, there have been extensive researches in modeling and control of them. Having the computer model of EAF helps power quality studies and development of control improvement strategies. In this paper the Model of EAF with its subsystems, namely the electrical system, the electrode positioning dynamics and disturbances are analyzed separately. Robust P-type current and impedance controllers are designed and compared with together. The simulation results show that unlike current control, impedance control does not suffer from the interaction effect between three phases and has more efficient ability in disturbance rejection in arc furnace circuit.

154

98-E-PSS-105

ECONOIMIC ANALYSIS OF A PUMPED STORAGE PROJECT FOR IRAN GENERATING SYSTEM BASED ON A DYNAMIC MODELING A.R. Sohrabi Tavanir Co Iran Key words: Pumped Storage-Generating System-Economic Analysis

Abstract

This paper proposes a dynamic model for evaluation of a Pumped Storage Project (PSP) . The optimal expansion policy is determined by considering different alternatives (Types of units: Rodbar PSP(RPSP), Steam Turbine , 2 types of Gas Turbine and a Combined Cycle) . Based on this model dynamic assessment of different alternatives (over a 20 years period and with a target Loss Of Load Probability (LOLP)) provides economic justification for RPSP . Finally a sensitivity analysis on RPSP economic justification with respect to its capital cost determined also capital cost limit.

155

98-F-PSS-118

Linear Identification of Power System Including TCSC to Design Power Oscillation Damping Reza Pourramazan

Sadegh Vaez-Zadeh

Hamidreza Nourzadeh

Tehran University

Tehran University IRAN

K. N. Toosi University of Technology

Key words: Linear system identification, Low-frequency oscillations, Output error method, TCSC power oscillation damping

Abstract

As the power systems are expanded and becoming more complicated, it is necessary to develop fast and accurate modeling techniques to achieve power systems low-order models for stability studies. This paper presents a suitable open-loop linear identification method for TCSC power oscillation damping controller design. The parameters of an Output Error model structure are obtained and optimized by Prediction Error Method which uses two data sets for estimation and validation. The fitness of obtained models for three operating points and two different configurations of a two-area power system confirm the accuracy of this method. A TCSC power oscillation damping controller is then designed using these low-order models. Time domain simulations are provided to confirm the efficiency of the presented identification method for the design of TCSC power damping controller.

156

98-F-PSS-163

Enhanced Load shedding Method in Restructured Power System by Considering Estimation and Variations of Bids Shahram jadid

eysam Mashayekh

Center of Excellence for Power System Automation and Operation Iran University of Science and Technology Tehran-Iran

Key words: Load shedding, market dynamic model, frequency response

Abstract

In this paper an innovative enhanced load shedding method by considering voltage and frequency constraints in deregulated environments is proposed. This method is based on short term estimation of load price variations during the load shedding implementation and dynamic coupling between power systems and power markets. To forecast the required parameters for dynamic modeling of Pool markets, the least square method based on Kalman filtering theory is used. Finally, focusing on system frequency modeling and estimation of price variations, the optimal load shedding is implemented in IEEE-30 bus test system and results are presented.

157

98-F-PSS-171

Analysis of Methods of Short Circuit limitation in Khorasan's Region (1385,1390) Considering Reliability Mostafa Eidiani 1,2, Mohammad Hassan Modir Shanechi 3, Kazem Ameli 2,4 1. Assistant Professor, Azad University of Bojnourd, Faculty of Eng. 2. NarSys Consultant Engineering. 3. Associate Professor, Ferdowsi University of Mashad, Faculty of Eng. 4. Educator, Azad University of Torbat Hydarieh, Faculty of Eng.

Key words: Short Circuit Limitation, Khorasan's Region, Reliability, DIgSILENT Power Factory

Abstract

There are several methods that can be used to reduce fault levels in the network. Some of the important ones are listed in this paper. The methods used in this study are based on modeling of the Khorasan network (1385 and 1390) and considering the reliability, protection and operation. We use DIgSILENT Power Factory in this study.

158

98-E-PSS-207

Application of Simulated Annealing Method in Strategic Bidding of Gencos S. Soleymania,b , A. M. Ranjbara,b, A. R. Shiranib, and M. Maramib a

Sharif University of Technology b Niroo Research Institute Tehran, Iran

Key words: Energy Market, Deregulation, Nash Equilibrium Point, Optimal Bidding Strategy, Simulated Annealing

Abstract

This paper describes a new method that uses Simulated Annealing (SA) method for analyzing the competition among Generating Companies (Gencos) where they have incomplete information about their opponents. Each Genco models its opponents with their generating cost coefficients. The proposed methodology employs the Supply Function Equilibrium (SFE) for modeling a Genco’s bidding strategy. Gencos change their bidding strategies until Nash equilibrium points are obtained. Nash equilibrium constitutes a central solution concept in game theory. The task of detecting the Nash equilibria of a finite strategic game remains a challenging up-to-date. This paper uses SA to compute Nash equilibria strategies of Gencos and then the obtained results are compared with another computational intelligence technique (Genetic Algorithm) and a mathematical method (GAMS/DICOPT).

159

98-E-PSS-268

Reliability Considerations in the Restructured Power System Scheduling A. Ehsani1, 3, A. M. Ranjbar1, 2, A. R. Shirani1, 2, M. Fotuhi-Firuzabad1 1. Sharif University of Technology 2. Niroo Research Institute 3. Iran Grid Management Company Tehran-Iran Key words: Reliability, Restructuring, Scheduling

Abstract

Electric power systems are typically scheduled at least cost subject to technical and reliability constraints. This paper presents a probabilistic approach for reliability evaluation in restructured power system scheduling. A competitive structure is proposed which includes a purchasing agency with centrally optimized scheduling (MaxISO structure). Spinning and nonspinning reserves are considered in the proposed approach. The value of risk is deduced from the generation model. The required generation model is constructed using the outage replacement rate (ORR) of units. The load forecast uncertainty is included in reliability evaluation. This is due to the increased uncertainty associated with competition. The concept of area risk curves is used to allow the inclusion of non-spinning reserve. The performance of the proposed approach is verified through simulation studies using a test system.

160

98-F-PSS-277

A Suitable Structure for Reliability Studies in Power System Planning

Key words: Reliability,Generation Planning, Transmission Planning

Abstract

Reliability is an important parameter in the planning, design and operation of an electric power system. The time period required to design, construct and commission a large generating station can be quite extensive (5 to 10 years) and for transmission lines or substations goes up to 2 or 3 years, depending on the environmental and regulatory requirements. It therefore becomes necessary to determine the system requirements considerably in advance of the actual unit or transmission equipments in-service date. In advance countries, reliability criterions are very important issue in generation and transmission system planning. Therefore , reliability studies should be considered in electric network planning. In this paper, two practical algorithms are presented for geneation and transmission level of system planning. With using these algorithms, an unique routine can be applied for reliability studies in IRAN. This paper focuses on planning for generation and transmission studies with a practical case study in Iran. Two practical studies for generation and transmission planning are conducted for FERC(Fars Electric Regional Company).

161

98-E-PSS-298

Allocation of Reactive Power to Bilateral Transactions Using Energy Transaction Factors Pouria Maghouli, Mostafa Parniani Sharif University of Technology IRAN Key words: Bilateral Transactions, Energy Transaction Factors, Reactive Power Allocation

Abstract

The new trend in electricity market considers reactive power as an ancillary service which should be paid for it. Unbundling reactive power support leads to a necessity for an equitable and fair allocation mechanism for this support. The allocation mechanism is a prerequisite for a pricing scheme. In this paper an online algorithm using ‘energy transaction factors’ is presented and developed. Numerical results and comparisons show its accuracy.

162

98-F-PSS-346

Economic Effects of Generators outage and Transmission Lines Outage on Power System Security R. Ghazi

M. Ghayeni

Professor

PhD student

Electrical Eng. Dept. Faculty of Engineering Ferdowsi University of Mashhad Iran

Key words: Power System Security, Economic Effects, Line Outage, Generator Outage

Abstract

In this paper the effects of transmission line and generator outage on the economic parameters of system are investigated, so as to determine the importance of these components in the security of the system. The forced or programmed outage of these components lead to increased cost associated with the cost of production, transmission and losses of the system. Based on the incurred costs, lines and generators are ranked which can be used in the maintenance scheduling problem and also for providing appropriate economic signals to the investors for generation expansion planning.

163

98-E-PSS-385

FAILURE ANALYSIS AND RELIABILITY EVALUATION of POWER TRANSFORMERS M.Mirzaie1,2

A.Gholami1

F.Aminifar1, 3

R.Saeedfar1

1-Iran University of Science & Technology (IUST) 2-Mazandaran University 3-Sharif University if Technology Tehran, Iran

Key words: Reliability Evaluation, Subtransmission Transformer, Weibull Distribution, Failure

Abstract

Failures of transformers in subtransmission systems not only reduce reliability of power system but also have significant effect on power system performance since one of the important components of any system quality is reliability of that system. To enhance utility reliability, failure analysis and rates, failure origin and physical damage causes must be study. This paper describes a case study of the reliability of subtransmission transformers (63/20 kV) installed in Mazandaran province, operated in subtransmission system. The information obtained from Mazandaran Regional Electric Company. The results of study and analysis on 60 substation including more than 110 transformers installed in subtransmission system show that the failure modes of transformers can be represented by Weibull distribution. Weibull statistics have been widely used and accepted as a successful mathematical method to predict the remaining life time of any equipment. Useful conclusions are presented both for power systems operators and manufactures for improving the reliability of transformers.

164

98-F-PSS-426

Fault Level Reduction of Ramin Power Plant Abbas Nasiri

Homayoon Berahmandpour Niroo Research Institute Islamic Republic of Iran

Key words: fault level reduction, network splitting, series reactor, transient stability

Abstract

Power network extending leads to increase fault level of substations that in some one may be greater than circuit breaker capability. By Iran 1390 network plan, fault level of Ramin power plant substation will be increased out of circuit breakers capability. This paper introduces several methods that can be used to reduce fault level and also presents studies performed to evaluate the impact of “network splitting” and “current limiter reactor” on fault level of Ramin power plant substation. Studies include short circuit and transient stability analysis.

165

98-F-PSS-484

Site Selection for Gas Power plants Using GIS Sara Beheshtifar M.J. Valadanzouj K. N. Toosi University of Technology Iran Key words: Site Selection, GIS, Power plant, Boolean Logic Model, Index Overlay model

Abstract

In Iran, the electric power demand has grown rapidly over the past years. A demand study for the country shows the need for new capacity to meet the growing electric demand. Therefore, it’s necessary to increase the power supply by constructing new power plants. One of the most important factors, which should be considered in new power plant construction process, is the location of the plant. The suitability of selected site for power plant affects the amount of generated energy and the cost of it. Suitable sites should be determined on the basis of technical, economical and socio-environmental issues. Therefore, multiple criteria should be considered in this process. GIS along with appropriate models and spatial analysis method can be used to define the suitability of different locations for the construction of power plants. This research focused on determining suitable locations for construction of gas-fired power plants. At first, important parameters in power plant sitting were identified. Then, the maps of studied area were prepared. Boolean and index overlay methods were used for integrating of maps. Finally the suitable locations for the construction of power plant were selected prioritized.

166

98-F-PSS-509

Static Security Assessment of Tie Lines in Iran’s North-West Transmission Network Using Neural Networks Atabak Mashhadi Kashtiban Faculty of Electrical and Computer Engineering, Tabriz University Iran Key words: Static Security, Tie Line, Neural Network

Abstract

In this paper multilayer perceptron neural networks are used for Static security assessment of tie lines on the Iran’s north-west transmission network To this end, the voltage drop on all tie lines is defined as the performance index, and four security levels are defined. The system is divided into two parts; all loads in both parts are varied according to predefined load-time curves. Then, two scenarios are considered: in the first scenario there is no structural change in power system. In the second scenario it is assumed that some lines are tripped due to voltage drop. Input data of neural network is obtained from DIgSILENT software. To speedup the neural network training, we use back-propagation algorithm with declining learning rate factor. Obtained results show that for the first scenario the average classification errors are 2.22% and 3.2% on the training set and the test set, respectively. For the second scenario, these error rates are increased to 4/6% and 5.3%.

167

98-F-PSS-538

Impact of Distributed Generators on Distribution System Voltage Stability M.Sedghi MS Student of Power Engineering University of Tehran

S.Afsharnia Assistant Professor of Power Engineering University of Tehran

Key words: Distributed generation, Voltage Stability, Synchronous Generator, Distribution System

Abstract

This paper presents the impact of synchronous generator for distributed generation application on the distribution system voltage stability. For this purpose, the dynamic behavior of a typical distribution system including a synchronous generator is simulated through Matlab/Simulink for different output powers of generator and under the three phase fault. In addition, the effect of employing cables and over head lines as system feeders is analyzed. Furthermore, impact of load demand on the voltage of buses is shown under the above-mentioned conditions. Simulation results show that in three phase short circuit condition, if generator operates in the maximum rated output power, it’s probable to voltage instability. Besides, it can be understood that due to lower value of cable reactance, voltage stability is more attainable in this case compared to the overhead line one.

168

98-F-PSS-563

Economic Evaluation of Dispersed Generation Plan in Comparison with Grid Extension Plan for Remote Electrification Habib Rajabi Mashhadi

Mohammad Farshad

Assistant Professor

Power Engineer

Javad Sadeh

Modjtaba Rouhani

Assistant Professor

Assistant Professor

Electrical & Computer Department, Faculty of Engineering Ferdowsi University of Mashhad Mashhad-Iran Central Committee of Research of Electrical Utility of Khorasan

Key words: Economic Evaluation, Present Worth, Dispersed Generation, Grid Extension, Microturbine

Abstract

In developing countries around the world there are too many residential and industrial places with no access to the main electricity grids. Economic evaluations can help us to make appropriate decisions for serve these offgrid consumers. There were too many efforts and programs to improve dispersed generation technologies and today these resources are developed sufficiently. Dispersed generation represents an opportunity to quickly increase the quality of life for remote off-grid consumers. This paper presents procedure of economic evaluation of dispersed generation plan in comparison with grid extension plan for remote off-grid loads electrification. A case study will be used to applying the proposed method. Sensitivity analysis will be done in the case study to know sensitivity of the economic evaluation results to economic parameter changes.

169

98-F-PSS-621

Kalman Filtering in the Linear Optimal Control and Dynamic Stability of the Multi-Machines Power System with Optimal Placement of Stabilizers Peyman.Naderi

Amir.Vasebi

S.M.Tagi.Bathaee

Phd Studendt Of K.N.Tusi University of Technologi And Academic Member of Islamic Azad University-Borujerd Branch

M.S Studendt Of K.N.Tusi University of Technologi

Academic Member of K.N.Tusi University of Trchnology

Key words: Power System Stabilizer, Synchronism, Kalman Filter, System Modes

Abstract

In this paper, first the dynamic model of multi- machine power system has been shown and State space equations near the operating point clarified. Then by using sensitivity analyzes the relation between system states and oscillatory modes has been considered and all of the states with higher affect on unstable modes existence, noticed and then machines which need to have stabilizers specified. One the effective design methods of power system stabilizers, is the linear optimal control (LOC) and this method needs the state feedback of the system. Due the far from states, this method may busy the communication chanels for communicated of states. For solving this problem, With using the kalman estimator, the estimated states used in LOC. Finally simulation results of a four-machine power system have been considered to show the effectiveness of the proposed method and compare with another effective method.

170

98-F-PSS-637

Joint Energy and Reserve Dispatching in Restructured Power Systems Dr. Ali-Akbar Gharaveisi

Dr. Masoud Rashidi-Nejad

Nader Hazrati

Shahid Bahonar University of Kerman (SBUK) Electrical Engineering Department Iran

Key words: Spinning Reserve Allocation, Restructuring, Ancillary Services, Genetic Algorithm

Abstract

In restructured environment, reserve provision as one of the most important ancillary services, is an independent system operator duty. Allocated reserve capacity for reliability requirements in power systems causes replacing a part of deliverable energy capacity of units. Spinning reserve provision without considering physical constraints for energy may cause the inconsistent energy and reserve allocation. For consistent allocation as well as optimal allocation, energy and reserve must be dispatched jointly. In this paper we analyze the joint energy and spinning reserve dispatch as an optimization model using genetic algorithm.

171

98-F-PSS-650

Power System Transient Stability Analysis using Corrected Energy Function G.R. Kamyab

M. Ehsan

Gonabad Azad Eslami University

Sharif University

With Contribution of the Standards and Research Office of Khorasan regional electric power Company

Key words: Power system transient stability analysis; Critical fault clearing time; Transient energy function

Abstract

One of the main objectives of the power system transient stability analysis is determination the critical fault clearing time (Tcr). The method of using transient energy function (Kakimoto method) is a fast and direct method for computing critical fault clearing time. In this paper, we illustrate using the method in some cases, like high loading states, we obtain non accurate values for Tcr. Therefore in these cases, we propose to use the corrected energy function to obtain accurate results. The corrected energy function includes corrected kinetic energy function and corrected potential energy function that we define these energies in this paper. In some cases of using the corrected energy function, we must make more attention that we introduce these cases in this paper. A four bus power system example is given to illustrate the ability of the proposed method.

172

98-F-PSS-651

Network Transmission Expansion Planning for Increasing competition and Decreasing Energy Not Supplied G.R. Kamyab

H.Rajabi Mashhadi

M. Fotuhi

Azad Eslami University Mashhad Ferdowsy University Sharif University With Contribution of the Standards and Research Office of Khorasan regional electric power Company

Key words: Transmission expansion planning, Deregulated power systems

Abstract

Transmission network plays a critical role in providing access to all participants in a competitive market for supply and delivery of electric power. With electrical load growth, transmission expansion planning must be performed timely and properly. Restructuring of power systems has changed the some objectives of transmission expansion planning. In this paper, we discuss transmission expansion planning problem aiming minimization the non competition and energy not supplied costs. Therefore, we define and compute the non competition cost and the cost of energy not supplied due to transmission constraints for different possible plans firstly. Then we use the sum of the non competition cost, the cost of energy not supplied due to transmission constraints, and investment cost for choosing optimum plan. The proposed method is very simple to implementation and don't need extreme data and large computation. The method represents the structure of costs containing the non competition cost, the cost of energy not supplied due to transmission constraints, and investment cost. A six bus power system example is given to illustrate the ability of the proposed method.

173

98-F-PSS-655

Study of the L and Z Index in Comparison with Changing Active and Reactive Load M.Ghorat

H.Rastegar E.Goodarzy Amir kabir University of Technology Islamic Republic Of Iran

B.Moradzadeh

Key words: voltage Stability, Voltage collapse, Stability index, Contingency, Line Outage

Abstract

Since a couple of decades ago voltage stability assessment has received an increasing attention due to the complexity of power system. With the increase in power demand and limited power sources has caused the system to operate at its maximum capacity. Therefore, a study that is able to determine the maximum capacity limit before voltage collapse must be carried out so that necessary precaution can be taken to avoid system capacity violation. In previous papers introduced some index for prediction of voltage instability. In this paper, we used Lmn and Z ratio index for distinction of voltage instability in comparison with line outage, also we analysis the sensitivity of these index in comparison with changing active or reactive power and determining place of instability in network. we use the 6-bus and 24-bus IEEE for testing. MATLAB and PSAT software have been used for simulating.

174

98-F-PSS-679

Modeling and Comparison of Various Methods for Static Analyzing of Voltage Stability on Khorasan Power Network Hamed Asadi

Mehdi Davarpanah

Majid Sanaye Pasand

Electrical & Computer Engineering Faculty University of Tehran Iran

Key words: Static voltage stability, Modal Analysis, Fast Analysis, VCPI, FVSI

Abstract

In this Paper, three different methods for static analyzing of voltage stability, including the Modal Analysis, VCPI Fast Analysis & FVSI Fast Analysis, have been simulated on Khorasan 76-bus power network. The function of all mentioned methods, have investigated in various kinds of system loading till critical point for voltage stability. The most reliable kind of analysis for static voltage stability of the current state of power system has been recognized according to the comparison of all kinds of the methods. The critical buses and lines of Khorasan power network have been the base of this comparison.

175

98-F-PSS-690

Costumer’s Load Forecasting on the Basis of Using Neural Networks Y. Mohammadian-R, Hani Raoof-S Ferdowsi University of Mashhad, Electrical Engineering Department

Key words: Load Forecasting, Artificial Neural Networks, Load Profile

Abstract

In order to nonlinear increased in customer’s usage of energy, and with respect to the power market, the existence of a method for load forecasting seems to be essential. Recently, artificial neural networks play an important rule in modeling and estimating of nonlinear functions. In the method which is presented here, using neural networks cause important advantages in load forecasting problem in Khorasan. Simulations demonstrate several significant improvements with the proposed approach.

176

98-E-PSS-711

Application of New FACTS Device (CUPFC) In the Transient Stability Enhancement of AC Transmission Systems A. Ajami1, S.H. Hosseini2, G. B. Gharehpetian 3 1: Electrical Engineering Department of Azerbaijan University of Tarbiat Moallem, Tabriz 2: Electrical & Computer Engineering Faculty of Tabriz University, Tabriz 3: Electrical & Computer Engineering Faculty Amirkabir University of Technology, Tehran

Key words: FACTS, CUPFC, UPFC, Power Oscillations Damping, Transient Stability Abstract

The UPFC is the most elegant device of FACTS controllers. It consists of two voltage source converters with one common DC link capacitor that are connected in parallel and in series. Each converter can independently generate or absorb reactive power. The ordinary UPFC has 4 control variables (phase and magnitude of shunt and series converters). Using these control variables it is possible to control the line active power flow, sending or receiving end reactive power, AC bus voltage and DC link voltage. Because of the limited number of control variables, the ordinary UPFC is not capable of controlling the line active and reactive powers of two machine system, simultaneously. To overcome this problem, a new topology of UPFC has been used. This new FACTS device is named center node UPFC (C-UPFC) installed at the midpoint of transmission line. The proposed device consists of three IGCT based voltage source converters. A shunt converter is connected at the midpoint of two series connected converters. In this paper the capabilities of this device will be discussed. The theory, transient and power flow models of a new FACTS device, CUPFC, are presented in this paper. Also, a control system for this device is presented. The presented model and control system of C-UPFC is validated with help of the PSCAD/EMTDC simulation program. In this paper CUPFC is simulated under different operating conditions. 177

98-F-PSS-763

Developing a Framework for Transmission Planning Standard in Iran Z. Madihi Bidgoli Niroo Research Institute Key words: planning standard, transmission system ,framework

Abstract

The interconnected transmission systems are the principal media for achieving reliable electric supply. They tie together the major electric system facilities, generation resources, and customer demand centers. These systems must be planned to operate reliably within thermal, voltage, and stability limits while achieving their major purposes. Transmission system planning may be done corresponding to applicable standards that contain basic rules and procedures for reliable planning in transmission system. In recent years, especially with restructuring in power system and forming electricity market, there is much more necessity to developing an applicable planning standard. In this paper, a proposed framework for transmission planning standard is presented.

178

98-F-PSS-778

Failure Analysis for transmission network reliability study Niki Moslemi1

Davood Jalali1

Hamid Danaee1

Felor Nikoorai2

1. Niroo Research Institute 2. Azerbaijan Regional Electric Company Key words: reliability, failure analysis, component indices, interruption indices

Abstract

Reliability study is one of the important studies of power systems. By reliability analysis the weak points of the network can be determined .The quantitative reliability evaluation permit reliability component indices to be computed from failure analysis of the constituent components of the system and interruption indices in all load points to be calculated from interruption data of outage in past time. In this paper is explained that how can use the results of reliability studies in the transmission network operation and design and whit attention to the reliability analysis results, some offers are produced for increasing the reliability of network. The Azerbaijan transmission network is considered as case study.

179

98-F-PSS-782

Suggestion of Indices and Method for Security Based Contingency ranking M.B. Abolhasani Jabali1,2 M. Mohammadi1 M. Abedi1 G.B. Gharehpetian1 1-Electrical Engineering Department, Amirkabir University 2-Iran Grid Management Company(IGMC)

Key words: security, contingency, voltage collapse, corrective actions

Abstract

Any event in a power system may results in system instability or voltage collapse. As a result each event can lead to a lot of technical or economical problems, and the system can not continuously preserve its security. Investment is a solution for the security enhancement but the resources are limited. As a result the contingency ranking must be done to select the projects with high priority for investment. The contingency ranking can be done using security indices. These indices should include loading conditions and uncertainty and voltage security. Corrective actions have been considered using optimum power flow and required load shedding.

180

98-E-PSS-802

New Momentum Adjustment Technique for Levenberg-Marquardt Neural Network Training Used in Short Term Load Forecasting M.H.Khosravi.Z

S. Barghinia

P. Ansarimehr

Department of Power System Operation, Niroo Research Institute (NRI) Tehran, IRAN

Key words: Short Term Load Forecasting, Artificial Neural Networks (ANN), Levenberg-Marquardt (LM) Algorithm

Abstract

One of the important requirements for operational planning of electrical utilities and also transactions of electrical power markets is the prediction of hourly load up to several days, known as short term load forecasting (STLF). Nowadays, intelligent methods, specially, artificial neural network (ANN) is the dominant method when it comes to STLF. The Levenberg-Marquardt (LM) algorithm has been extensively used as training method for ANNs. In this work, a new momentum adjustment technique is implemented for training ANN of Iran national power system (INPS) STLF. The performance is compared with conventional LM algorithm with other momentum adjustment techniques. The new method of momentum adjustment for LM algorithm improves learning of ANN for STLF of INPS in the sense of error and time consumption.

181

98-E-PSS-827

Solving OPF problem with the Hybrid GA and the Hybrid PSO Algorithms and Comparing with the Gradient-based Methods Mostafa Majidpour, Ashkan Rahimi-Kian School of Electrical & Computer Engineering University of Tehran, Iran Key words: Optimal Power Flow (OPF), Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Newton's Method, Hybrid GA, Hybrid PSO

Abstract

In this paper we evaluate using the Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) method for solving Optimal Power Flow (OPF) in large scale power systems. We have proposed the Hybrid GA (HGA) and the Hybrid PSO (HPSO) methods, which are combination of modern AIbased methods and traditional gradient-based methods, to increase the convergence speed and to reduce the risk of divergence in critical system conditions (i.e. transmission line flow limits). The proposed method was tested with the IEEE 118-bus and 300-bus test systems and compared with one gradient-based algorithm (Newton's method), pure GA and pure PSO methods.

182

98-F-PSS-859

Optimal sizing & selection distributed generation for different geographical regions of Iran S.M.T.Bathaee K.N.T.Toosi University Of Technology

S.H.Hosseinean Ahangari Islamice Azad Univercity South Branch

Key words: Distributed Generation, Energy, Capacity Factor, Simulation, Homer software

Abstract

The subjects of distributed generation are still a challenging and attractive research topic in the world. In present, although the companies of this kind generator always reduce costs of design manufacture and services. But so far, electrical price is not comparative with conventional methods. Device cost for DG technologies often calculate per kilo watt of electrical generation in market. In this paper, first electric generation cost of DG devices with energy potential in different geographical parts of Iran evaluated and then simulation of small system power distributed with Homer software as case studies for sample city of Tehran is investigated.

183

98-E-PTL-110

Investigation of partial discharge pulses propagation in single-core and three-phase XLPE cables Vahid Parvin and Mehdi Vakilian Electrical Engineering Department Sharif University of Technology Key words: partial discharge, H.F. signal propagation, Semi conducting layers, XLPE cable, Detection, Propagation

Abstract

Partial discharge in XLPE cables can be employed to detect occurrence of any discharge in them. if any water treeing or insulation deterioration takes place in this type of cables, it would fail very fast and thus on time detection of the causes of failures such as partial discharge signal is very important to improve the reliability of power system network and to extend the life time of the cable. The presence of semi-conducting layers results in a high attenuation of high frequency signals amplitude during their propagation through the cable, and it will be difficult to detect and estimate the actual level of partial discharge in its location. To evaluate the attenuation of high frequency signals, frequency response of the semi-conducting layers voltages and the shield current are determined, While a calibrator signal generator, is employed during these measurements At the sending end of the single core and 3phase cables, voltages of semi-conducting layers and the currents of shield wires at sending end and receiving end are measured, and compared. The ATP frequency dependent cable model is employed for simulation of PD propagation in single phase cable and the results are verified against the measured data on an XLPE cable test setup of this work.

184

98-F-PTL-221

Simulation of Cable Freezing based on IRAN Weather Data Shahram Ardabili Niroo Research Institute , Structure Dep. IRAN Key words: tower loading, ice load, cable freezing, statistical analysis

Abstract

Developing a national loading code for power transmission towers requires statistical analysis of two principal random variable namely wind speed and ice thickness which lead to meteorological zonation (or micro zanation) of IRAN. Proper measurements are done in meteorological station for wind speed, so accordingly statistical analysis may be done simply. But for freeze (and ice thickness) there are not any measurments. So, the simulation methods are used frequently. In this paper the CRREL simulation method is introduced and the resulting of statistical analysis of heavy and normal ice based on 40 years meteorological data of Tehran city is mentioned.

185

98-F-PTL-222

Developing Software in order to Reliability Analysis of Transmission Lines Structures Shahram Ardabili Niroo Research Institute , Structure Dep. IRAN Key words: structural reliability, design of transmission towers, statistical analysis

Abstract

The usefulness of reliability analysis in design of structures is well recognized. Each random variable is modeled by means of probability density function and so the safety of structure is determined with reliability index. In the “Determination and Evaluation of Transmission Line Structures Reliability” project, uncertainty of towers loading duo to wind and ice loads was studied and corresponding PDFs based on 50 years meteorological data, for 8 city in Iran. And also based on Latin hypercube sampling method a software which is called STRAS is developed with VB in order to analysis the reliability of power transmission line towers. Data includes three files. First one defines the structure geometry and configuration second defines the general loading parameters and profiles specifications and the last one covers the generated value for loading and resistance random variables. Contour plot of element probability of failure with active window and failure modes of structure are output of this software.

186

98-F-PTL-291

Subtransmission System tower model for lightning Surge Over Voltage analysis *’***S.E.Naghibi ** S.Najafi *** S.A.Sajadi * Islamic Azad University of behshar ** Amirkabir University of Technology *** Mazandaran Regional Electric Company Key words: Lightning Surge, Flashover, Back Flashover, Multistory, EMTP

Abstract

This paper present a novel approach to evaluation of flashover and back flashover in medium voltage towers. Our studies carry out with three types of power system tower models, including multistory tower model, simple multistory tower model and simple distributed line model in which the traveling wave transmitted with light speed. Simulations are done with EMTP software with all kinds of tower models. Obtained results show that what kinds of towers are optimal, and hence are better than the others.

187

98-F-PTL-453

Make discount for R.O.W. in 20kV electric power transmission lines of Iran 1,2

Reza Sirjani

1,2

Amir Mehrtash

1

Ziba Fakheri Darian

1. Power Engineering Consultants (Moshanir) 2. K.N.Toosi University of Technology Iran

Key words: Right Of Way, 20kV Transmission lines, Iran R.O.W. Standard

Abstract

Nowadays, in according to fast grow in urbanity and buildings construction and crowd in many areas also increase in land price and on the other hand public safety, the Right Of Way (R.O.W.) becomes essential especially inside cities and it requires careful consideration. In the last approved instruction of Iran Ministry of energy about R.O.W., acceptance criteria of R.O.W. is only states on voltage levels and span length while moreover other parameters such as conductor type, insulator type, line parameter also effect on R.O.W. which must account in its design calculations. According to this approved instruction, R.O.W. for 20kV electric power transmission lines is 3 meters without discount and reduction is related to get permit from Ministry of energy. In this paper, first class R.O.W. for 20kV electric power transmission lines of Iran at city inside calculated with account different parameters and reduction have imposed and conclusions are presented.

188

98-F-PTL-645

Right of Way and Comments for Restructuring the Standard in Iran 1,2

S. Kamalinia

1,3

A. Mehrtash

1

M.P. Arabani

1. Power Engineering Consultant, Moshanir 2. University of Tehran, Electrical Engineering Faculty 3. K.N.T University IRAN

Key words: Transmission Lines Design, Environmental Impacts, Electromagnetic Fields, Audible Noise, Radio Interference

Abstract

From the public view point, impacts of electrical origin are some of the most important, due to their special effect on daily life. Electric and magnetic fields tend to cause concern to the general public because of their alleged effects on human health. Radio interference and audible noise may be unpleasant to those who live near a power line. The aim of this paper is to show how different design parameters of overhead lines affect on electrical impacts and the way to reduce these impacts by using appropriate parameters. It is notable that, for purposing the acceptable level of environmental impacts, interferences with electrical devices and utilities are not considered in this evaluation which is certainly should be considered in each special case. Values have been studied herein for 400 kV lines as representative of EHV lines for single and double circuit in different phase configurations, considering self-supporting structures, which are frequently used.

189

98-F-PTL-662

Introduction a New Algorithm for Passivity Enforcement in Network Equivalent for Electromagnetic Transient Studies B. Porkar1, M. Vakilian1, and S. M. Shahrtash2 1. Dep. of Electrical Engineering, Sharif University of Technology (SUT) 2. Dep. of Electrical Engineering, Iran University of Science and Technology (IUST) Tehran - Iran

Key words: Passivity enforcement, rational functions, network equivalent, electromagnetic transient studies

Abstract

This paper introduces a new technique for passivity enforcement of rational functions presented in network equivalent of VLSI systems. This new algorithm applied well in VLSI circuit applications seems able to overcome the drawbacks of the present algorithm for passivity enforcement in applications of power system and especially to network equivalent for electromagnetic transient studies. The main advantages of introduced technique are: 1) The new algorithm guarantees that the correction for passivity in a certain frequency region dose not introduce new region of passivity violation. 2) It can be applied where the passivity violations may be large. 3) Since the proposed method is non-iterative it will be efficient and fast where the regions of passivity violation are numerous. The mentioned advantages are vital especially for ensuring passivity of multiport network equivalent approximated by rational functions.

190

98-F-PTL-676

Evaluation of Aeolian Vibration Failure Range in Overhead Transmission Lines, And It’s Decreasing by Stock Bridge Damper Effect Hamid Mazaheri 1, Morteza Sadeghi 2 1- M.S of Mechanical Engineering, IRNF Co. 2- Assistant Professor, Department of Mechanical Engineering, Tabriz University

Key words: Power Transmission Lines, Aeolian Vibration, Stockbridge Damper

Abstract

In this paper the forced vibration of a power transmission line with an attached non-conservation dynamic absorber (Stockbridge Damper) is investigated. At the firs step, an equivalent two-degree of freedom (two-dof) dynamical model of the Stockbridge damper is introduced and modal analysis method it is transformed to two one-dof models. This transformation allows us to obtain the load effects of the Stockbridge on cable, which greatly simplifies the solution of the coupled equations of Stockbridge and cable model. The results show a good agreement with the coupled model.

191

98-F-PTL-791

Cause Of Overhead Line Interruption In F.R.E.C, Due To Galloping, Non-Suitable Designing And Performing H.R.jahromi, A.Safari, A.Dashti

A.GHolami, H.mohseni

A.Barzegarzade, GH.Heshmati Fars Regional Electric Company- Iran

I.U.S.T University,Tehran University Iran

Key words: galloping, interruption, operation, overhead line

Abstract

In recent years, several events have been happened in F.R.E.C (Fars regional electric company) transmission and sub transmission line, which were due to non-suitable designing and performing, galloping phenomenon. In this article with investigation about galloping phenomenon, some of those events will analyze and finally, we will present some way for decreasing of such events.

192

12-E-PTL-795

Experimental Investigation to Determine Corona Inception Electric Field, Using a Rod-plane Configuration Hamid JAVADI*, Arash PEYDA, and M. FARZANEH NSERC / Hydro-Quebec / UQAC Industrial Chair on Atmospheric Icing of Power Network Equipment Université du Québec à Chicoutimi, Chicoutimi, Québec, Canada *Power and Water University of Technology (PWUT), Tehran, IRAN

Key words: Electric field, Corona, Rod-plane, Atmospheric parameters

Abstract

This paper deals with the measurement of the corona inception voltage for hemi-spherically capped rod-plane electrode configuration at the point of corona inception for a suitable range of radii on short air gap under AC power frequency voltage. Then, the effect of atmospheric pressure and temperature variation on the corona inception voltage by laboratory tests in comparing to correction factors of IEC standard atmospheric conditions is investigated. Utilising a rod-plane electrode configuration with a radius range of 0.25mm