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nosis of power transformers. Thus, incipient faults in power transformers can be identified directly by the degree of relation. The application of this new method to some transformers has given promis- ing results. Keywords: Transformer fault diagnosis, dissolved gas analysis (DGA), extension theory, matter-element model. Preprint Order Number: PE-580PRD (05-2002) Discussion Deadline: October 2002 Power System Analysis, Computing, and Economics An Individual Welfare Maximation Algorithm for Electricity Markets Weber, J.D.; Overbye, T.J. Author Affiliation: Power World Corporation; University of Illi- nois at Urbana-Champaign. Abstract: An algorithm that allows a market participant to maxi- mize its individual welfare in electricity spot markets is presented. The use of the algorithm in determining market equilibrium points, called Nash equilibria, is demonstrated. The start of the algorithm is a spot market model that uses the optimal power flow (OPF), with a full repre- sentation of the transmission system and inclusion of consumer bid- ding. The algorithm utilizes price and dispatch sensitivities available from the Hessian matrix and gradient of the OPF to help determine an optimal change in an individual's bid. The algorithm is shown to be successful in determining local welfare maxima, and the prospects for scaling the algorithm up to realistically sized systems are very good. Nash equilibria are investigated assuming all participants attempt to maximize their individual welfare. This is done by iteratively solving the individual welfare maximization algorithm until all individuals stop modifying their bids. Keywords: Power systems, economics. welfare maximization, OPF, markets, Nash equilibrium. Preprint Order Number: PE-122PRS (03-2002) Discussion Deadline: August 2002 Note that this abstract was included in the June 2002 issue of IEEE Power Engineering Review, but author information was missing. It ap- pears in this issue in its corrected form. Real-Time Network Simulation with PC-Cluster Hollman, J.A.; Marti, J.R. Author Affiliation: University of British Columbia. Abstract: This paper presents a new architecture layout for a real-time power system simulator based on a distributed cluster of IBM PC-compatible desktop computers. A real-time network simulator based on a PC cluster can successfully cope with the size requirements of growing power systems and the computational demands of fast tran- sient studies. A powerful product has been developed using off-the-shelf Pentium II 400 MHz workstations with a commercial real-time operating system, standard I/O interfaces, and a multimachine networking scheme. Models based on the standard tool for power systems transients simulations, the EMTP program, opti- mized for real-time performance assure accurate simulation results. Keywords: Real-time, power system simulator, PC cluster, EMTP, OVNI. Preprint Order Number: PE-391PRS (05-2002) Discussion Deadline: October 2002 A New Phase-Coordinate Transformer Model for Y Bus Analysis Moorthy, S.S.; Hoadley, D. Author Affiliation: Royal Melboume Institute of Technology. Abstract: A new method of modeling three-phase transformers has been developed. The method can represent transformers with two or more windings and can incorporate the effects of interphase coupling, particularly the lowered impedance of three-phase units to zero-sequence magnetizing currents. For two-winding transformers, the model requires only four data items per transformer and can still be used even in the absence of some of them, in which case it simplifies to existing well-established modeling techniques. Keywords: Phase-coordinate analysis, power flow, short-circuit, transformer models, Y bus. Preprint Order Number: PE-561PRS (05-2002) Discussion Deadline: October 2002 Power System Analysis Using Space Vector Transformation Aller, J.M.; Bueno, A.; Paga, T. Author Affiliation: Universidad Simon Bolivar. Abstract: The space vector transformation used in machine vector control is applied to power system analysis. The proposed method is used to model electric machines, power electronic converters, trans- formers, and transmission lines and analyze power sources and loads with different connections (delta and wye). this method can also be ap- plied to analyze steady-state or transient phenomena and unbalanced sources, including harm,onics. Models obtained with this method are as simple as those of the per-phase approach. With the space-vector trans- formation, instantaneous active and reactive power concepts can be generalized, and new power system control strategies can be developed when power electronic converters are used. Steady-state, transient be- havior, and harmonic analyses examples and applications are presented to illustrate the performance and advantages of the proposed method. This method can be extended to unbalanced systems (e.g., unsymmetric faults) using instantaneous symmetrical components in polyphase balanced circuits. Keywords: Power system simulation, time domain analysis, circuit simulation, transmission line matrix methods, transformers, rectifiers, ac machines, induction machines, power electronics, power system harmonics. Preprint Order Number: PE-577PRS (05-2002) Discussion Deadline: October 2002 Transmission Cost Allocation by Cooperative Games and Coalition Formation Zolezzi, J.M.; Rudnick, H. Author Affiliation: Universidad Catolica De Chile. Abstract: The allocation of costs of a transmission system to its us- ers is still a pending problem in many electric sector market regula- tions. This paper contributes with a new allocation method among the electric market participants. Both cooperation and competition are de- fined as the leading principles to fair solutions and efficient cost alloca- tion. The method is based mainly on the responsibility of the agents in the physical and economic use of the network, their rational behavior, the formation of coalitions, and cooperative game theory resolution mechanisms. The designed method is applicable to existing networks or to their expansion. Simulations are made with sample networks. Re- sults conclude that adequate solutions are possible in a decentralized environment with open access to networks. Comparisons with tradi- tional allocation systems are shown, and cooperative game solutions compare better in economic and physical terms. Keywords: Cooperative game theory, nucleolus, open access, transmission cost allocation, transmission expansion, shapley value. Preprint Order Number: PE-541PRS (05-2002) Discussion Deadline: October 2002 IEEE Power Engineering Review, August 2002 64
