General Model for Representing Variable-Speed Wind ... - IEEE Xplore

Using Two Multivariate Methods for Line Congestion Study in Transmission Systems Under Uncertainty Deladreue, S.; Brouaye, F.; Bastard, P; Peligry, L. Author Affiliations: Supelec, France; EDF-R&D Service Etudes de Reseaux, France. Abstract: Two multivariate methods (correlation analysis and principal components analysis) are used to forecast which lines may be simultaneously congested. These statistical methods are applied to a database that takes into account transmission planning uncertainties such as localization of new independent power producers and new eligible customers (i.e., customers who can choose their energy supplier), and level of international exchanges. To face the very large number of possible configurations, a design of experiment is used to create the database. A complete active/reactive power flow program is used to simulate the power system. The results show the relevance of the proposed methods as applied to a 21-bus power system test case. Knowing which lines will be simultaneously congested may help the system operator to make decisions in short-term operation (congestion management) as well as in long-term planning (grid reinforcement). Keywords: Correlation analysis, line congestion, open electricity market, power flow, power system planning, principal component analysis, uncertainty. Preprint Order Number: PE-181PRS (08-2002) Discussion Deadline: January 2003

General Model for Representing Variable-Speed Wind Turbines in Power System Dynamics Simulations Slootweg, J.G.; De Haan, S.WH.; Polinder, H.; Kling, WL. Author Affiliations: Delft University of Technology, The

Netherlands. Abstract: A tendency to erect ever more wind turbines can be observed in order to reduce the environmental consequences of electric power generation. As a result of this, in the near future wind turbines may start to influence the behavior of electric power systems by interacting with conventional generation and loads. Therefore, wind turbine models that can be integrated into power system simulation software are needed. A model that can be used to represent all types of variable-speed wind turbines in power system dynamics simulations is presented. The modeling approach is commented upon, and models of the subsystems of which a variable speed wind turbine consists are discussed. Some results obtained after incorporation of the model in PSS/E, a widely used power system dynamics simulation software package, are presented and compared with measurements. Keywords: Variable-speed wind turbine, modeling, simulation, power system dynamics, grid integration, PSS/E. Preprint Order Number: PE-233PRS (08-2002) Discussion Deadline: January 2003

A New Preconditioned Conjugate Gradient Power Flow Dag, H.; Semlyen, A. Author Affiliations: Istanbul Technical University, Turkey; University of Toronto, Canada. Abstract: A new solution methodology for the constant matrix, decoupled power flow problem is presented in this paper. The proposed method uses the conjugate gradient method instead of the traditional direct solution of Ax = b for updating the power flow variables. The conjugate gradient method is accelerated with an approximate inverse matrix preconditioner obtained from a linear combination of matrix-valued Chebyshev polynomials. The new method has been tested on several systems of different sizes. In terms of speed, the method is comparable to the fast decoupled load flow in serial environments, but 56

it is more amenable to parallel and vector processing since it contains only matrix-vector multiplications. Keywords: Chebyshev polynomials, conjugate gradient method, decoupled load flow, iterative methods, preconditioner. Preprint Order Number: PE-270PRS (08-2002) Discussion Deadline: January 2003

Reliability Worth Assessment of High-Tech Industry Yin, S.A.; Chang, R.F.; Lu, C.N. Author Affiliations: National Sun Yat-Sen University, Taiwan;

Kao Yuan Institute of Technology, Taiwan. Abstract: This paper introduces a new approach to customer interruption cost evaluation that recognizes the dispersed nature of the cost data. The proposed method is designated as the possibility distribution approach and provides a realistic and effective assessment of the losses incurred by high-tech industry electrical users due to power failures. Fuzzy linear regression models are used to describe the distribution and dispersed behaviors of interruption costs. Bootstrap technique is used to generate a sampling distribution of small samples so that confidence intervals of interruption costs of different high-tech sectors can be obtained. Using the obtained cost models, interruption costs and reliability worth of high-tech industries that require higher reliability and premium power service, can be properly assessed. Keywords: Interruption costs, reliability worth, fuzzy regression. Preprint Order Number: PE-424PRS (08-2002) Discussion Deadline: January 2003

Using DEA To Measure the Relative Efficiency of the Service Center and Improve Operation Efficiency Through Reorganization Chien, C.F.; Lo, F.Y; Lin, J.T. Author Affiliations: National Tsing Hua University, Taiwan; Taiwan Power Company, Taiwan. Abstract: Data envelopment analysis (DEA) has become a practicable approach to evaluate the relative efficiencies of decision-making units in various contexts. A DEA study was conducted to measure the relative efficiencies of 17 service centers of the NAN-TOU electricity distribution district of Taiwan Power Company (TPC). Altematives for reorganizing the service centers via efficiency measurement were investigated. The results showed that the proposed reorganization alternatives have better efficiency scores. Based on DEA evaluations, we provide specific directions for the inefficient service centers to improve their operation efficiencies and thus maintain the competitive advantage of TPC in facing power market liberalization. Keywords: Data envelopment analysis (DEA), relative efficiency, reorganization, power systems, Taiwan Power Company (TPC). Preprint Order Number: PE-509PRS (08-2002) Discussion Deadline: January 2003

Var Compensation by Sequential

Quadratic Progranuning

Perez Abril, I.; Gonzalez Quintero, J.A.

Author Affiliations: Central University of Las Villas, Cuba. Abstract: This paper presents an application of the sequential quadratic programming method to find the optimal sizing of shunt capacitors and/or passive filters for maximizing the net present value resulting from energy loss reduction while taking investment cost into account and complying with IEEE Standard 519. The proposed methodology allows the simultaneous solving for fixed and switched var compensators by considering a characteristic load variation curve for each linear and nonlinear load. Keywords: Power system harmonics, optimization methods. Preprint Order Number: PE-521PRS (08-2002) Discussion Deadline: January 2003 IEEE Power Engineering Review, November 2002