重谐波污染系统中电容器和电力电子接口分布式电源的最佳配置和尺寸(IJISA-V6-N7-7)

I.J.IntelligentSystemsandApplications,2014,07,52-59PublishedOnlineJune2014inMECS()DOI:10.5815/ijisa.2014.07.07Copyright©2014MECSI.J.IntelligentSystemsandApplications,2014,07,52-59OptimalPlacementandSizingofCapacitorandPower-ElectronicInterfacedDistributedGenerationinHeavyHarmonicPollutedSystemsMohamadrezaHeydariSharafdarkolaiStaffmemberofMazandaranregionalelectriccompany,IranEmail:[e-mail]duniversityofyazd,IranEmail:[e-mail]berofazaduniversityofyazd,IranEmail:[e-mail]:[e-mail]—Presenceofdistributedgeneration(DG)indistributionsystemshassignificantimpactsontheoperationalcharacteristicsofthesesystems,alsousingcapacitorforreactivecompensationandlossreductionissocommon.Injectedharmoniccurrentsfromnon-linearloadsintodistributionsystemdistortallofvoltagesandcurrentsandmustbeconsideredwhenplacingthecapacitorbankssothattheresonancewillnotoccur.DistributedGenerationisoftenconnectedtothenetworkviapower-electronicinterfacesforapropercouplingwiththedistributionnetworks.Invertersarecapableofproducingharmoniccomponentsandcanbeusedasancillaryservicesforreducingharmonicsbydesigningofapropercontrollingsystem.Inthispaperdiscreteparticleswarmoptimization(DPSO)approachisusedfortheoptimalplacementandsizingofdistributedgenerationsandcapacitorsindistorteddistributionsystemsforsimultaneousvoltageprofileimprovement,lossandtotalharmonicdistortion(THD)reduction.Constraintsincludevoltagelimit,voltageTHD,number/sizeofcapacitorsandgenerators.Forevaluatingtheproposedalgorithm,theIEEE33-bustestsystemismodifiedandemployed.IndexTerms—Capacitor,DistributedGeneration,DiscreteParticleSwarmOptimization,Harmonic,OptimalPlacemen,Power-Electronic,Resonance.I.INTRODUCTIONStudieshaveindicatedthatapproximately13%ofgeneratedpowerisconsumedaslossatthedistributionlevel.Inaddition,withtheapplicationofloads,thevoltageprofiletendstodropalongdistributionfeedersbelowacceptableoperatinglimits.Alongwithpowerlossesandvoltagedrops,theincreasinggrowthinelectricitydemandrequiresupgradingtheinfrastructureofdistributionsystems.InthissituationDISTRIBUTEDGENERATION(DG)mayplayanimportantroleintheelectricpowersystems.DistributedGenerationisasmallelectricpowersourceconnectedtothedistributionnetworknearconsumption.SHUNTcapacitorsareinstalledindistributionsystemsinordertoreducepowerlosses,regulatebusvoltageandimprovepowerfactorbygeneratingreactivepower.Alloftheseadvantageswillbeachievedonlyonthecondition,these(DG&Capacitor)placedinproperbuses.Anyimproperplacingmayadversesystem'scondition.Oneassumptionthatisstillbeingmadeinformulatingthecapacitorplacementproblemisthatallloadsareconsideredlinear.Inpractice,aportionoftheelectricloadisnonlinearduetothewide-spreaduseofelectronics-baseddevices.Nonlinearloadsmustbetakenintoaccountforplacingofcapacitorsbecausetheyshowlowimpedanceatharmonicfrequencieswhichissoidealforflowingharmoniccurrentsthrowthemandtheymayamplifyharmonicamplitudeatresonancefrequenciesanddamagethesystem'scomponents.DistributedGenerationisoftenconnectedtothenetworkviapower-electronicinterfaces(converterorinverter)forapropercouplingwiththedistributionnetworks.Theseconverters(inverters)arewell-designedandcontrolledtogenerateanalmostpuresinusoidaloutputvoltage.Ontheotherhand,Invertersarecapableofproducingharmoniccomponentsandcanbeusedasancillaryservicesforreducingharmonicsbydesigningofapropercontrollingsystem.Thiscontrollingsystemcontrolstheinverter'sswitchesinsuchawayaparticularharmoniccomponentisproducedintheoutputoftheinverterwhichopposesitscounterpartontheloadside.Thiswillleadtocancellationofharmonics.Therehavebeensomestudiesforoptimalplacingsuchas:tabuOptimalPlacementandSizingofCapacitorand53Power-ElectronicInterfacedDistributedGenerationinHeavyHarmonicPollutedSystemsCopyright©2014MECSI.J.IntelligentSystemsandApplications,2014,07,52-59search[1],analyticalapproaches[2].[3],second-orderalgorithm[4],meta-heuristicapproaches[5].[6],fuzzy-GAalgorithm[7],etc.Mostofthesetechniquessufferfromtheinabilitytoescapelocaloptimalandburdenheavycomputationaltime.PSO(particleswarmoptimization)isagoodmethodwhichisfastandhasabilitytoescapelocaloptimal.PSOisaself-adaptivesearchoptimizationwasintroducedbyKennedyandEbhart[8].PSOhasbeenappliedtomanyoptimizationproblemssuchas:dynamicsystems[9],optimalcapacitorplacementindistributionsystem[10],constrainedoptimization[11],multi-objectiveoptimizationproblems[12],etc.SomeworkshaveusedPSOforoptimalplacingofcapacitors,itwasconsideredasacontinuousproblembutasweknowcapacitorsarecommerciallyavailableindiscretesizes,sointhispaperamodifiedversionofPSOwhichissuitablefordiscreteproblemsandiscalleddiscreteparticleswarmoptimization(DPSO)orbinaryparticleswarmoptimizationisused.Therestofthispaperisorganizedasfollows:insectionIIanancillaryserviceforimprovingsystem'spowerqualitywillbeintroduced.ProblemformulationfortheobjectivefunctionforimprovingvoltageprofileandminimizationoflossandTHDispresentedinsectionIII.InsectionIVth