Grid-Friendly Connecting of Constant-Speed Wind Turbines Using ...

Announcement of Approved Transactions Papers

Transactions Abstracts his section of IEEE Power Engineering Review serves to announce the approval of technical papers for publication in future issues of one of the three PES Transactions. The abstracts afford access to the essence and main contributions of each published paper. The abstracts are listed by Technical Committees, which appear in alphabetic order. To Order Technical Paper Preprints, Contact IEEE Customer Service, +1 800 678 4333 or +1 732 981 0060, fax +1 732 981 9667, e-mail [email protected]. The IEEE member price for each paper Preprint is $3.50 plus delivery charges (nonmember price is $6.50 plus delivery charges). When you contact IEEE Customer Service, make sure that you identify the item you are ordering as a Preprint (not as a paper, reprint, article, etc.), and be sure to provide the Preprint order number. Discussion Deadlines for the papers are included with each technical paper abstract.

Electric Machinery IPM Synchronous Machine Drive Response to Symmetrical and Asynunetrical Short Circuit Faults Welchko, B.A.; Jahns, T.M.; Soong, WL.; Nagashima, J.M. Author Affiliation: University of Wisconsin at Madison, Wiscon-

sin; University of Adelaide, Australia; General Motors-Advanced Technology Vehicles, Torrance, California. Abstract: A closed-form solution is presented for the steady-state response of interior permanent magnet (IPM) synchronous machines to symmetrical short circuits including the effects of q-axis magnetic saturation. Machine response to single-phase asymmetrical short circuits is also investigated. Experimental data is presented to verify predicted behavior for both types of short circuits. It is shown that single-phase asymmetrical short circuit faults produce more severe fault responses with high pulsating torque and a significant threat of rotor demagnetization. A control strategy that purposely transitions such faults into symmetrical three-phase short circuits can minimize the fault severity and associated demagnetization risks. Implications for the design of IPM machines with improved fault tolerance are discussed. Keywords: Interior permanent magnet, synchronous machine, short circuit fault, inverter shutdown, variable speed drive, protection. Preprint Order Number: PE-074EC (07-2002) Discussion Deadline: December 2002

A Direct Torque Controlled Interior Permanent Magnet Synchronous Motor Drive Without a Speed Sensor Rahman, M.F.; Zhong, L.; Haque, M.E.; Rahman, M.A. Author Affiliation: University ofNew South Wales, Sydney, Australia. Abstract: This paper reports results of further investigation of the so-called direct torque control (DTC) technique to an interior permanent magnet (1PM) synchronous motor drive. This torque control technique for IPM motors requires no dq-axes current controllers and coordinate transIEEE Power Engineering Review, October 2002

formnation networks. A completely sensorless 1PM motor drive with DTC,

which uses a new speed estimator from the stator flux linkage vector and the torque angle, is presented. It is shown that including the torque angle in the estimation process results in a far more accurate transient speed estimator than what is reported in the existing literature. Keywords: Interior permanent magnet motor, direct torque control, stator flux linkage, rotor flux linkage, speed estimator, mechanical shaft sensor, current control, rotor reference frame, coordinate transformation. Preprint Order Number: PE-066EC (07-2002) Discussion Deadline: December 2002

Energy Development and Power Generation A Method of Tracking the Peak Power Points for a Variable Speed Wind Energy Conversion System Datta, R.; Ranganathan, VT. Author Affiliation: ABB Corporate Research Centre, Ladenburg,

Germany; Indian Institute of Science, Bangalore, India. Abstract: In this paper, a method of tracking the peak power in a wind energy conversion system (WECS) is proposed, which is independent of the turbine parameters and air density. The algorithm searches for the peak power by varying the speed in the desired direction. The generator is operated in the speed control mode with the speed reference being dynamically modified in accordance with the magnitude and direction of change of active power. The peak power points in the P - o curve correspond to dP / do = 0. This fact is made use of in the optimum point search algorithm. The generator considered is a wound rotor induction machine whose stator is connected directly to the grid and the rotor is fed through back-to-back PWM converters. Stator flux-oriented vector control is applied to control the active and reactive current loops independently. The turbine characteristics are generated by a dc motor fed from a commercial dc drive. All the control loops are executed by a single-chip DSP controller TMS320F240. Experimental results show that the performance of the control algorithm compares well with the conventional torque control method. Keywords: Peak power point tracking, rotor side control, speed control mode, turbine characteristics, wind energy conversion system, wind turbine, wound rotor induction machine. Preprint Order Number: PE-559EC (07-2002) Discussion Deadline: December 2002

Grid-Friendly Connecting of Constant-Speed Wind Turbines Using External Resistors Thiringer, T. Author Affiliation: Chalmers University of Technology, Goteborg, Sweden. Abstract: In this paper an alternative method of connecting fixed-speed wind turbines with active pitch mechanisms or variable-slip generators is proposed and evaluated. Instead of using the conventional soft starter, external resistors are used. The method was evaluated via laboratory tests on a 15 kW machine, as well as theoreti57

cally on a 1 MW wind turbine. The proposed method causes smaller grid power quality impact, especially on inductive grids, compared with soft starters. This means that it will be possible to install constant-speed wind turbines to weaker grids utilizing this method. Keywords: Wind energy, power quality, capacitors, resistors. Preprint Order Number: PE-121EC (07-2002) Discussion Deadline: December 2002

Conversion of Unused Heat Energy to Electricity by Means of Thermoelectric Generation in Condenser Kyono, T.; Suzuki, R.O.; Ono, K. Author Affiliation: Kyoto University, Kyoto, Japan. Abstract: Thermoelectric power generation has the potential to re-

cover a large amount of energy loss at the vapor condensers in the steam-based power plants. A suitable arrangement of thermoelectric modules was designed from the heat transfer theory in the cylindrical heat exchanger. Even under the practical operation limits, 150 kW can be generated by the thermoelectric conversion. Keywords: Thermoelectric energy conversion, surface condenser, steam-based power plants. Preprint Order Number: PE-123EC (07-2002) Discussion Deadline: December 2002

performance which measures the potentiality of gains and the potentiality of losses taking into account the multidimensional aspect of risk, the vagueness and nuances of the decision maker's preferences, and the different kinds of uncertainties. The three steps proposed are portfolio construction, portfolio evaluation, and portfolio ranking. This requires modeling of uncertainties, contracts, and the decision maker's preferences. The example of a large consumer of electric energy and a comparison with the value-at-risk system are presented. The proposed approach is applied to appraise different strategies for a Swiss utility. Keywords: Decision making, uncertainty, risk analysis, strategic planning, contracts, power system economics, fuzzy sets. Preprint Order Number: PE-649PRS (07-2002) Discussion Deadline: December 2002

Power System Analysis, Computing, and Economics Distribution Access Pricing: Application of the OFTEL Rule to a Yardstick Competition Scheme Recordon, E.; Rudnick, H.

Insulated Conductors Results of Partial Discharge Measurements in a Long-Distance 275 kV GIL Miyazaki, A.; Takinami, N.; Kobayashi, S.; Araki, T.; Nishima, H.; Hata, H.; Yamaguchi, H.; Yamauchi, T.; Hama, H. Author Affiliation: Chubu Electric Power Company, Inc., Nagoya, Japan; Sumitomo Electric Industries, Ltd., Osaka, Japan; Furukawa Electric Company, Ltd., Chiba, Japan; Mitsubishi Electric Corporation, Amagasaki, Japan. Abstract: In this paper we introduce a newly developed measuring system for partial discharges (PD) in after-laying tests on site for a long-distance gas insulated transmission line (GIL) in a tunnel. We evaluate the length of harmful particles for the overvoltages to be considered for the Shinmeika-Tokai GIL. The length of particles detectable by the PD sensors is compared with the length of harmful particles. The highly sensitive PD measuring system took advantage of low noise levels in the tunnel. We applied the system to the after-laying test on site and confirmed that the developed system was effective to verify the required performance of a long distance GIL in a tunnel. Keywords: Gas insulated transmission line, partial discharges, metallic particles, measuring system, after-laying test. Preprint Order Number: PE-016PRD (07-2002) Discussion Deadline: December 2002

Power Engineering Education Economic Performance of Contracts in Electricity Markets: A Fuzzy and Multiple Criteria Approach Schmutz, A.; Gnansounou, E.; Sarlos, G. Author Affiliation: Swiss Federal Institute of Technology, Lausanne, Switzerland. Abstract: In competitive electricity markets, consumers and suppliers are exposed to price risk, quantity risk, and other risks such as credit risk. These risks can be managed through an adequate portfolio of contracts. The goal of the approach proposed is to help a market player to appraise portfolios of contracts from the point of view of the economic 58

Author Affiliation: Pontificia Universidad Catolica De Chile, Santiago, Chile. Abstract: This paper formulates an access-pricing model applied to electricity distribution, based on the OFTEL model, originally structured to price telecommunications monopolistic essential facilities. The aim is to achieve an optimal access price charge in an environment where a distribution network monopoly serves both regulated and nonregulated customers. The nonregulated market faces competition, therefore, the competitors must use the network to reach their customers. A usage-based hybrid model is proposed to couple with a tariff scheme for regulated customers, which uses yardstick competition. A way to set appropriated opportunity costs by the use of the OFTEL model is introduced. Finally, the paper focuses on properly recognizing both regulated distribution and competitive supply costs. The scheme is assessed within the Chilean regulatory scheme, proposing a way to establish marginal and fixed distribution costs for distribution companies. Keywords: Power sector deregulation, access pricing, distribution pricing, distribution costs, supply costs, opportunity costs. Preprint Order Number: PE-473PRS (07-2002) Discussion Deadline: December 2002

Enhancement of Power System Data Debugging Using Gap Statistic Algorithm-Based Data Mining Technique Huang, Sj.; Lin, J.M. Author Affiliation: National Cheng Kung University, Tainan, Taiwan. Abstract: In this paper, a gap statistic algorithm (GSA)-based data mining technique is applied to enhance the data debugging in power system operations. In the proposed approach, the GSA technique is embedded into a neural network frame in anticipation of improving the detection capability of bad data. Thanks to the clustering capability exhibited by GSA in which the number of clusters can be optimally determined, the proposed approach becomes highly effective to localize the group of abnormal data. This proposed approach has been tested through the data collected from different scenarios made on an IEEE 30-bus system and 118-bus systems. Test results reveal the feasibility of the method for the data diagnosis applications. Keywords: Gap statistic algorithm, data mining. Preprint Order Number: PE-571PRS (07-2002) Discussion Deadline: December 2002 IEEE Power Engineering Review, October 2002