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Optimal Des'ign of Power System StabilizersUsing Particle Swarm Opt'imization

Abido, M.A.

Author Affiliation: King Fahd University of Petroleum and Min-erals, Saudi Arabia

Abstract: In this paper, a novel evolutionary algorithm-based ap-proach to optimal design of multimachine power system stabilizers(PSSs) is proposed. The proposed approach employs the particleswarm optimization (PSO) technique to search for optimal settings ofPSS parameters. Two elgenvalue-based objective functions to enhancesystem damping of electromechanical modes are considered. The ro-bustness of the proposed approach to the initial guess is demonstrated.The performance of the proposed PSO-based PSS (PSOPSS) under dif-ferent disturbances, loading conditions, and system configurations istested and examined for different multimachine power systems.Eigenvalue analysis and nonlinear simulation results show the effec-tiveness of the proposed PSOPSSs to damp out the local as well as theinterarea modes of oscillations and work effectively over a wide rangeof loading conditions and system configurations. In addition, the poten-tial and superiority of the proposed approach over the conventional ap-proaches are demonstrated.

Keywords: PSS design, particle swarm optimization, and dynamicstability.

Preprint Order Number: PE-586EC (04-2002)Discussion Deadline: September 2002

Improving Voltage Disturbance Rejectionfor Variable-Speed Wind Turbines

Saccomando, G.; Svensson, J.; Sannino, A.

Author Affilation: University of Palermo, Palermo, Italy;Chalmers University of Technology, Goteborg, Sweden

Abstract: In this paper, the effect of voltage dips on variable-speedwind turbines using VSCs is treated. Three different current controllersfor the VSC are described and implemented. Their performance is eval-uated when the converter is subject to different types of voltage dips.Both simulated and measured dips are used. The effect of thephase-angle jump of the dips is also taken into account.

Keywords: Variable-speed wind turbines, voltage dips (sags),power quality, voltage source converter, converter control.

Preprint Order Number: PE-641EC (04-2002)Discussion Deadline: September 2002

Power System Analysis,Computing, and Economics

Value of Security: Modeling Time-DependentPhenomena and Weather Conditions

Rios, M.A.; Kirschen, D.S.; Jayaweera, D.; Nedic, D.P; Allan, RN.

Author Affiliation: UMIST, Manchester, U.K.Abstract: Deterministic security criteria provide a degree of security

that may be insufficient under some operating conditions and excessivefor others. To determine an appropriate level of security, one should per-form a probabilistic cost/benefit analysis that balances the cost of the se-curity margin against its benefits, i.e., the expected societal cost of theavoided outages. This paper shows how a previously published methodbased on Monte Carlo simulation can be enhanced to take into accounttime-dependent phenomena such a cascade tripping of elements due tooverloads, malfunction of the protection system, and potential powersystem instabilities. In addition, the importance of using failure rates thatreflect the weather conditions is discussed. Studies based on theSouth-Western part of the transmission network of England and Walesdemonstrate the validity of the models that have been developed.

Keywords: Power system security, power system operation,weather modeling, probabilistic models.

Preprint Order Number: PE-004PRS (04-2002)Discussion Deadline: September 2002

Electricity Market Equilibrium Models:The Effect of Parameterization

Baldick, R.

Author Affiliation: University of Texas at Austin, Austin, TXAbstract: In this paper, an example from the literature is used to

compare Coumot and supply function equilibrium models of bid-basedelectricity markets both with and without transmission constraints. It isdemonstrated that the parameterization of the supply function modelhas a significant effect on the calculated results. In particular, severalresults reported in the literature are artifacts of assumptions in theparameterization of the model.

Keywords: Market power, Coumot equilibrium, supply functionequilibrium, transmission constraints.


Power Flow Control Approach To PowerSystems With Embedded Facts Devices

Insulated ConductorsXiao, Y.; Song, YH.; Sun, Y.Z.

Insuring Adequate Spacing between UndergroundDistribution Conductors in Conduit and Gas Lines

Parker, TJ.; Ward, DJ.

Author Affiliation: Georgia Tech/NEETRAC, Forest Park, GA;Dominion Virginia Power, Richmond, VA

Abstract: The effects of faults occurring on secondary cables in aplastic conduit energized at 240 V were evaluated under simulated fieldconditions. Secondary cables were intentionally faulted inside polyvi-nyl chloride (PVC) and polyethylene (PE) conduits. The test setup rep-resents a typical, residential single-phase circuit consisting of apadmount transformer with a length of secondary cable. The fault char-acteristics (voltage and current waveforms) and temperatures on the ex-terior of the conduit near the fault were recorded. The condition of theconduit after the fault was also assessed.

Keywords: Underground distribution lines, NESC.Preprint Order Number: PE-015PRD (04-2002)Discussion Deadline: September 2002

Author Affiliation: Brunel Univeristy, Uxbridge, Middlesex, U.K.;Tsinghua University, Beijing, China

Abstract: This paper focuses on developing a steady-state powerflow control approach for systems incorporating flexible ac transmissionsystems (FACTS) devices. Based on a power injection model ofFACTSdevices and an optimal power flow model, a novel versatile power flowcontrol approach is formulated, which is capable of implementing powerflow control incorporating any FACTS device flexibly. Different fromexisting FACTS device control approaches, the active and (or) reactivepower injections are taken as independent control variables. Using thisapproach, the Jacobian matrix need not be changed, although variousFACTS devices possess different physical models and different controlparameters. Furthermore, it allows the efficient integration ofFACTS de-vices into the existing power system analysis and control programs.Physical limits of the FACTS devices are also considered in the model.Numerical results on a reduced practical system and a 1500-bus practicalsystem with various FACTS devices are presented to illustrate the vigor-ousness of the proposed approach.

Keywords: Flexible ac transmission systems, power flow.Preprint Order Number: PE-500PRS (04-2002)

IEEE Power Engineering Review, July 2002 53

Discussion Deadline: September 2002

A Software Architecture for Power Market SupportingSystem and Reengineering of Legacy EMS

Zhao, Q.; Huang, G.M.; Wu, X.; Luo, X.

Author Affiliation: Texas Instruments; Texas A & M University;Fujitsu Network Communications; ISO NE, Inc.

Abstract: In this paper, a heterogeneous software architecturalstyle is designed for the web-based software system to support andelectronic commerce solution for deregulated power markets, which isflexible for various power market structures and extendible for thefast-changing industry environment. A wrapping technique is designedto transfer the legacy energy management system (EMS) modules intoreusable components for the power market supporting software system.

Keywords: Software architectural style, electronic commerce, en-ergy management system, power market.


Hedging With Futures Contracts ina Deregulated Electricity IndustryTanlapco, E.; Lawarree, J.; Liu, C.C.

Author Affiliation: University of WashingtonAbstract: This paper is a statistical study of direct and cross hedg-

ing strategies using futures contracts in an electricity market. A com-parison of the strategies is based on the standard deviation or risk of thevalues of the hedging positions. Results indicate that the use of electric-ity futures contracts is superior to using other related futures contractssuch as crude oil.

Keywords: Electricity deregulation, risk management.Preprint Order Number: PE-041PRS (04-2002)Discussion Deadline: September 2002

Multiple Criteria Decision-Makingand Risk Analysis as Risk ManagementTools for Power Systems PlanningLinares, P

Author Affiliation: Universidad Pontificia ComillasAbstract: Uncertainties in power systems planning are gaining

importance due to the liberalization of the electricity industry and theincreasing concem for the environmental impact of electricity genera-tion. This paper presents an electricity planning model that deals withuncertainty and its associated risk at two levels: at the first level, byminimizing environmental risk through a multiple-criteria model; atthe second level, by perfonning a risk analysis consistent with the mul-tiple criteria model used before and which applies classical decisionrules for selecting the best planning strategy under uncertainty. Resultsshow that the incorporation of additional criteria produce much moreflexible and efficient strategies, which greatly reduce environmentalrisk at a little cost increment while the risk analysis process selects flex-ible and robust strategies for the scenarios analyzed.

Keywords: Power system planning, decision-making, risk analysis,uncertainty.


Trading Wind Generation inShort-Term Energy Markets

Bathurst, G.N.; Weatherill, J.; Strbac, G.

Author Affiliation: UMIST, Manchester, U.K.Abstract: Even with state-of-the-art forecasting methods, the

short-term generation of wind farms cannot be predicted with a highdegree of accuracy. In a market situation, these forecasting errors lead

to commercial risk through imbalance costs when advance contracting.This situation is one that needs to be addressed due to the steady in-crease in the amount of grid-connected wind generation, combinedwith the rise of deregulated, market-orientated electricity systems. Inthe presence of imbalance prices and uncertain generation, a method isrequired to determine the optimum level of contract energy to be soldon the advance markets. Such a method is presented here using Markovprobabilities for a wind farm and demonstrates substantial reductionsin the imbalance costs. The effect of market closure delays and fore-casting window lengths are also shown.

Keywords: Wind energy, risk analysis, Markov processes, NETA,energy markets.


An Efficient Algorithm for Assessing ReliabilityIndices of General Distribution Systems

Wang, Z.; Shokooh, F.; Qiu, J.

Author Affiliation: Operation Technology, Inc.Abstract: This paper presents a practical reliability assessment al-

gorithm for distribution systems of general network configurations.This algorithm is an extension of the analytical simulation approach forradial distribution systems. In the proposed algorithm, the meshed net-work is first converted to a radial network. All network elements are di-vided into three main classes according to their probability to obtainpower supplies from different directions. Accordingly, three differentmethods are employed to obtain two types of reliability topology zonesfor the elements. The algorithm is efficient for large-scale ra-dial/meshed distribution systems and can accommodate the effects offault isolation and load restoration. The validity and effectiveness of theproposed algorithm is demonstrated by applying a computer programwhich was developed based on the proposed algorithm to a number oftest systems and hundreds of real distribution networks.

Keywords: Reliability analysis, distribution systems, networkanalysis.


Dynamic Analysis of GenerationControl Performance Standards

Sasaki, T.; Enomoto, K.

Author Affiliation: Kansai Electric Power Co.Abstract: This paper presents an evaluation of the North American

Electric Reliability Council's (NERC) new control performance stan-dards, as they might be applied to the Westem Japanese 60 Hz system.Dynamic simulation of the systems frequency response, including theeffects of primary and secondary frequency control, power plant re-sponse, and load fluctuation characteristic were performed using a loadflow program during normal system operation. Parameter sensitivitieshave been studied for some of the pertinent control parameters influ-encing the generation control performance, including power plant andAGC response parameters, and amounts of generation under control forgovemor and AGO.

Keywords: Power system, generation control, control performancestandards, control area.


Adaptation in Load Shedding UnderVulnerable Operation Conditions

Jung, J.; Liu, C.C.; Tanimoto, S.L.; Vittal, V

Author Affiliation: Iowa State University; University of Washing-ton

Abstract: The proposed approach to avoiding catastrophic failuresin interconnected power systems uses a defeusive system based on

IEEE Power Engineering Review, July 200254