Preprint Order Number: PE-713PRS (8-2001). Discussion Deadline: January 2002. Modeling and Analysis of Custom. Power Systems by PSCAD/EMTDC.
Optimal Dispatch of Generating Units of the Itaipu Hydroelectric Plant Arce, A.
Author Affiliation: Itaipui Binacional, Brazil Abstract: This article is concemed with the optimal dispatch of generating units of Itaipu, the world's largest hydroelectric plant in operation. Itaipi is a 12.6 GW hydro plant, located on the Parana river in South America, composed of 18 identical 700 MW generating units. A dynamic programming model has been developed to optimize the number of generating units in operation at each hour of the day in order to attain the total generation scheduling of the plant in the most economic way. The model highlights the trade-off between start-up/shut-down of generating units and hydro power efficiency, taking into account variations in tailrace elevation, penstock head losses, and turbine-generator efficiencies. The methodology has been tested for a typical generation scheduling, and the results show that the number of the turbine-generator sets dispatched has a major influence on the overall hydroplant efficiency, and therefore it is a key aspect to be considered in the dispatch of hydro generating units. In the case of Itaipu, the economic benefits, in terms of greater power efficiency with respect to actual operation, are in the range of millions of dollars per year. Preprint Order Number: PE-713PRS (8-2001) Discussion Deadline: January 2002
Modeling and Analysis of Custom Power Systems by PSCAD/EMTDC Anaya-Lara, 0.; Acha, E.
Author Affiliation: The University of Glasgow, Scotland, U.K. Abstract: This paper addresses the timely 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 [2],[3]. The modeling approach adopted in this article is graphical in nature, as opposed to mathematical models embedded in code using a high-level computer language. The well-developed graphic facilities available in an industry standard power system package, namely, PSCAD/EMTDC, are used to conduct all aspects of model implementation and to carry out extensive simulation studies. Graphics-based models suitable for electromagnetic transient studies are presented for the following three custom power controllers: the distribution static compensator (D-STATCOM), the dynamic voltage restorer (DVR), and the solid-state transfer switch (SSTS). Comprehensive results are presented to assess the performance of each device as a potential custom power solution. The paper is written in a tutorial style and aimed at the large PSCAD/EMTDC user base. Keywords: Custom power, D-STATCOM, DVR, SSTS, PWM, voltage source converter. Preprint Order Number: PE-089PRD (8-2001) Discussion Deadline: January 2002
A Cobweb Bidding Model for
Competitive Electricity Markets Contreras, J.; Candiles, O.; de la Fuente, J.I.; Gomez, T.
Author Affiliation: Universidad De Castilla-La Mancha, Spain; Universidad Pontificia De Comillas, Spain Abstract: The new competitive framework that has been established in several electricity markets all over the world has changed the way that electric companies attain benefits. Under this new scenario, generation companies need to develop bidding models not only for the sake of achieving a feasible dispatch of their units, but also for maximizing their benefits. This paper presents a new bidding strategies model that considers the global policy of a company, but also specifies the bid of each generating unit. The proposed model produces a maximum price bid and an optimal bidding quantity by means of an iterative procedure using the generating company's residual demand curve. It is 56
based on an economic principle known as the cobweb theorem, frequently used to study stability in trading markets. A realistic case study from the Spanish daily electric market is presented to illustrate the
methodology. Keywords: Electricity markets, bidding strategies, residual demand, Nash-Coumot equilibrium, cobweb theorem. Preprint Order Number: PE-659PRS (8-2001) Discussion Deadline: January 2002
Power System Dynamic Performance
Reactive Power Support Services for Transmission Access
Valuation of Dynamic
Xu, W., Zhang, Y.; Da Silva, L.C.P.; Kundur, P., Warrack, A. Author Affiliation: University of Alberta, Canada; Powertech Labs Inc., Surrey, Canada Abstract: Competitive procurement of reactive power support services is rapidly becoming a reality for deregulated electricity markets. It has resulted in a great need to quantify the value of reactive power support from var sources. This article presents research results on the development of new concepts and schemes for equitable reactive power support valuation. Performance characteristics of the proposed method are determined and practical application issues are addressed. The validity of the method is verified through sensitivity studies. This work emphasizes that the valuation of reactive power support services should be based on their contributions to system security and stability. The dynamic var is the primary concern for the reactive power valuation problem. Keywords: Reactive power support, voltage security, ancillary services, and open access. Preprint Order Number: PE-328PRS (8-2001) Discussion Deadline: January 2002
Nonlinear Decentralized Disturbance Attenuation Excitation Control via New Recursive Design for Multimachine Power Systems Lu, Q.; Mei, S.; Hu, H.; Wu, F.F.; Ni, Y.; Shen, T. Author Affiliation: Tsinghua University, China; The University of Hong Kong, Hong Kong; Sophia University, Tokyo, Japan Abstract: In this article a new nonlinear decentralized disturbance attenuation excitation control for multimachine power systems is proposed based on recursive design without linearization treatment. The proposed controller improves system robustness to dynamic uncertainties and also attenuates bounded exogenous disturbances on the system in the sense of L2-gain [1]. Computer test results on a six-machine system show clearly that the proposed excitation control strategy can enhance transient stability of power systems more effectively than other excitation controllers. Keywords: Nonlinear system, power system stability, recursive design, disturbance attenuation, decentralized control. Preprint Order Number: PE-551PRS (8-2001) Discussion Deadline: January 2002
Power System Instrumentation and Measurement A Neural-Fuzzy Classifier for Recognition of Power Quality Disturbances Huang, J.S.; Negnevitsky, M.; Nguyen, D.T. Author Affiliation: University of Tasmania IEEE Power Engineering Review, November 2001
Abstract: This article presents a neural-fuzzy technology-based classifier for the recognition of power quality disturbances. The classifier adopts neural networks in the architecture of frequency-sensitive competitive leaning and learning vector quantization. With given size of code words, the neural networks are trained to determine the optimal decision boundaries separating different categories of disturbances. To cope with the uncertainties in the involved patten recognition, the neural network outputs, instead of being taken as the final classification, are used to activate the fuzzy-associative-memory recalling for identifying the most possible type that the input waveform may belong to. Furthermore, the input waveforms are preprocessed by the wavelet transform for feature extraction so as to improve the classifier with respect to recognition accuracy and scheme simplicity. Each sub-band of the transform coefficients is then utilized to recognize the associated disturbances. Keywords: power quality disturbances, pattern recognition, wavelet transform, neural networks, fuzzy associative memory. Preprint Order Number: PE- 1 14PRD (8-2001) Discussion Deadline: January 2002
Power System Operations Energetic Operation Planning Using Genetic Algorithms Leite, P.; Carneiro, A.; Carvalho, A. Author Affiliation: P. Leite, A. Carneiro, Sao Carlos Engineering School, Sao Paulo, Brazil; University of Guelph, Ontario, Canada Abstract: This paper investigates the application of genetic algorithms to optimize large, nonlinear complex systems, particularly the optimization of the operation planning of hydrothermal power systems. Several of the current studies to solve this kind of problem are based on nonlinear programming. This approach presents some deficiencies, such as difficult convergence, oversimplification of the original problem, or difficulties related to the objective function approximation. Aiming to find more efficient solutions for this class of problems, this paper proposes and investigates the use of a genetic approach. The characteristics of the genetic algorithms, such as simplicity, parallelism, and generality, can provide an effective solution to these problems. The paper presents the adaptation of the technique and an actual application on the optimization of the operation planning for a cascade system composed by interconnected hydroelectric plants Preprint Order Number: PE-774PRS (8-2001) Discussion Deadline: January 2002
A Continuous Strategy Game for Power Transactions Analysis in Competitive Electricity Markets Park, J.B.; Kim, B.H.; Kim, J.H.; Joung, M.; Park, J.K. Author Affiliation: Korea Electric Power; Anyang University; Seoul National University, Seoul, Korea Abstract: This article presents a game theory application for analyzing power transactions in a deregulated energy marketplace such as PoolCo, where participants, especially generating entities, maximize their net profits through optimal bidding strategies (i.e., bidding prices and bidding generations). In this article, the electricity market for power transactions is modeled as a noncooperative game with complete information, where the solution is determined in a continuous strategy domain having recourse to the Nash equilibrium idea. In order to provide more apprehensible analysis, we suggest a new hybrid solution approach employing a two-dimensional graphical approach as well as an analytical method. Finally, the proposed approach is demonstrated on a sample power system. Keywords: Deregulation, PoolCo model, spot market, game theory, continuous strategy. IEEE Power Engineering Review, November 2001
Preprint Order Number: PE-083PRS (8-2001) Discussion Deadline: January 2002
Simulation and Evaluation of Optimization Problem Solutions in Distributed Energy Management Systems Contreras, J.; Losi, A.; Russo, M.; Wu, F.F.
Author Affiliation: Universidad De Castilla-La Mancha, Spain; Universita Di Cassino; University of Hong Kong Abstract: Deregulation in electricity markets requires fast and robust optimization tools for a secure and efficient operation of the electric power system. In addition, there is the need for integrating and coordinating operational decisions taken by different utilities acting in the same market. Distributed energy management systems (DEMS) may help to fulfill these requirements. The design of DEMS requires detailed simulation results for the evaluation of its performance. To simulate the operation of DEMS from the optimization standpoint, a general purpose distributed optimization software tool, DistOpt, is used, and its capabilities are extended to handle power system problems. The application to the optimal power flow problem is presented. Keywords: Deregulation, distributed energy management systems, distributed optimization. Preprint Order Number: PE-407PRS (8-2001) Discussion Deadline: January 2002
Power System Relaying Multisensor Secondary Device for Detection of Low-Level Arcing Faults in Metal-Clad MCC Switchgear Panel Sidhu, T.S.; Sagoo, G.S.; Sachdev, M.S. Author Affiliation: University of Saskatchewan, Canada
Abstract: This paper describes the development of a multisensor device, based on four different physical phenomena, for reliable detection of low-level arcing faults in metal-clad switchgear. The proposed device was tested for actual arcing, generated on a low-voltage motor control center (MCC) panel, feeding a dry type 15kVA, 230/115 V Y/A transformer. Some results showing the performance of the developed device are presented in the paper. The device can also be applied for detection of arcing in power electronic drives, dry type transformers, gas insulated switchgear (GIS), generator bus-ducts, and other metal-clad electrical apparatus. Keywords: Metal-clad switchgear, arcing faults, multisensor-based protection. Preprint Order Number: PE-463PRD (8-2001) Discussion Deadline: January 2002
A Digital Simulator for Determining the Performance Limits of Computer Relays Mir, M. Al-Saleh, M. Author Affiliation: Umm Al-Qura University, Saudi Arabia Abstract: Unlike most other digital simulators that generate test waveforms for specific system configurations, playback previously recorded fault waveforms, or randomly generated artificial waveforms, the digital simulator presented in this paper generates the worst-case waveforms for specified bounds on noise components present in the relay input signals. As a result, the performance limits of a computer relay can be determined, for specified bounds on its noise components, by performing a single test only. The parameters that define the worst-case waveforms are obtained by utilizing a modified univariate search algorithm. The PC-based simulator was implemented using a general-purpose multifunction card and a graphical programming 57
