外文翻译--风电对电力系统角稳定性的影响.doc

1英文原文ImpactofWindPowerontheAngularStabilityofaPowerSystemAbstractWindenergyconversionsystemsareverydifferentinnaturefromconventionalgenerators.Thereforedynamicstudiesmustbeaddressedinordertointegratewindpowerintothepowersystem.Angularstabilityassessmentofwindpowergeneratorisoneofmainissuesinpowersystemsecurityandoperation.TheangularstabilityforthewindpowergeneratorisdeterminedbyitscorrespondingCriticalClearingTime(CCT).Inthispaper,theeffectofwindpoweronthetransientfaultbehaviorisinvestigatedbyreplacingthepowergeneratedbytwomaintypesofwindturbine,increasinggraduallyarateofwindpowerpenetrationandchangingthelocationofwindresources.Thesimulationanalysiswasestablishedona14busIEEEtestsystembyPSAT/Matlab,whichgivesaccesstoanextensivelibraryofgridcomponents,andrelevantwindturbinemodel.KeywordAngularStability,CCT,WindTurbine,WindPenetration,PSAT.IntroductionApowernetworkisacomplexsystem,whichisvulnerabletodisturbances.Atransientshortcircuitfaultisaverycommondisturbanceinapowersystem1.Itupsetstherotatingmachinesinthevicinityofthefault,causingthespeedsofthesemachines,andthepowerflowsinthenetworktooscillate.Whentheshortcircuitisclearedbydisconnectingthefaultedline,thegeneratorsthathaveacceleratedwilldecelerateandcomebackintosynchronismwiththerestofthesystem.Iftheydonot,andthesystembecomesunstable,thereisariskofwidespreadblackoutsandofmechanicaldamagetogenerators.Sothecriticalclearingtime(CCT)isthemaximumtimeintervalbywhichthefaultmustbeclearedinordertopreservethesystemstability2,3.Thereisnodoubtthatwindpowerwillplayapredominantroleinaddingcleanandnonpollutingenergytothecountrysgrid.However,asmorewindturbinesareconnectedtothegrid,theirimpactonthepowerqualityofservicespopulatedwithwindgenerationisbecomingmoreevident,soitisimportanttoanalyzethetransientstabilityofpowersystemincludingwindpowerstations4.Athree-phasefaultisappliedtoa14busIEEEtestsystem,andclearedbydisconnectingtheaffectedline.Inthispaper,thefocusislimitedtodetermineCriticalClearingTime(CCT)fortheseveralcasesbyobservingthetransitbehaviorsimulationofatestsystemduringgridfaultsusingaMatlabpowersystemanalyzetoolbox(PSAT)5.Thestructureofthispaperisasfollows.First,thewindmodelisdescribedbriefly；alsothewindturbineconceptsaredescribed.Then,thetestsystemandtheappliedmodelsarepresented.2Theoscillationofagroupofgeneratorsduringafaultisanalyzedbyobservingthetransientbehaviorforfollowingcases:A-Changingawindsourcelocates.B-Differentgeneratortechnologies.C-Increasinggraduallyarateofwindsourcespenetration.Toconclude,theresultsareclarifiedonthebasisofexistingtheoriesandcomparisonbetweendifferentcasesinordertochooseabestcaseandavoidaworseone.WindModelWindenergyistransformedintomechanicalenergybymeansofawindturbinewhoserotationistransmittedtothegeneratorbymeansofamechanicaldrivetrain.Thewind-powerequation6,7isgivenby:Pt=1/8d2v3Cpwhereistheairdensity,ristheturbineradius,isthewindspeed,andCpistheturbinepowercoefficientwhichrepresentsthepowerconversionefficiencyanditisafunctionoftheratiooftherotortip-speedtothewindspeed,termedasthetip-speed-ratio(TSR).Suchdisturbancesarethemostcommoninthegrid,thegriddisturbancesconsideredinthispaperareofshortduration,maximumafewhundredsofmilliseconds.Sincetheconsideredgriddisturbancesaremuchfasterthanwindspeedvariations,thewindspeedcanheassumedconstant.Therefore,naturalwindvariationsneednotbetakenintoaccount.Thewindspeedissettoaconstant15m/s.TurbineModelsTherearemanydifferenttypesofwindturbinesinusearoundtheworld,eachhavingitsownlistofbenefitsanddrawbacks8.Inthispapertwomaintypesofwindturbinesaretakenintoaccount:Aconstantspeedwindturbine(Fig.1a),whichconsistsofagridcoupledshort-circuitedinductiongenerator9.Thewindturbinerotorisconnectedtothegeneratorthroughagearbox.Thepowerextractedfromthewindislimitedinhighwindspeedsusingthestalleffect.Noactivecontrolsystemsareused.Avariablespeedwindturbinewithwoundrotorinductiongenerator(Fig.1b)doubly-fedinductiongenerator(DFIG).Therotorwindingissuppliedusingaback-to-backvoltagesourceconverter10.Asinthefirstcase,thewindturbinerotoriscoupledtothegeneratorthroughagearbox.Inhighwindspeedsthepowerextractedfromthewindislimitedbypitchingtherotorblades.3Figure1a.SquirrelcageinductiongeneratorFigure1b.Doubly-fedinductiongeneratorTestSystemThetestsystemforthisstudyispresentedinFig.2,itisderivedfromIEEEtestsystem；thisnetworkconsistsof14buses,5generators,11loadsand83branches.Thetransformersconnectinggeneratorstothegridareadjustedaccordingly.Windturbinesarethe2MWmachinesdescribedaboveinsection2.Notethatthegeneratorsdonotrepresentasinglemachinebutagroupofstronglycoupledgeneratorsandforthistestsystemthetotalpowerisdividedasfollow:Table1.ActivepoweroftestsystemgeneratorsGeneratorN12345Power(MW)61560602525Thedisturbanceinvestigatedisathree-phaseshort-circuitonBusnumber2.Thisthree-phase4faultrepresentsthemostseveredisturbancefortransientstabilityproblems.ItmustbenotedthatallsimulationsaredevelopedbyPSAT(version2.0.01).ResultsandDiscussionsImpactofLocationInordertoassumetheimpactofthewindpowertoangularstabilityofpowersystem,weincludedathreephasesymmetricalfaultthenwecalculatetheCCTcorrespondingtoacasewithoutwindsourceandotherscaseswhereawindsourceisconnectedtotestsystembydifferentBuses.Figure2.BasecaseWithoutaWindSourceTheBaseCaserepresentsthenormaloperationofthesystemwithoutanywindpowerconnectedtothesystem.Thecriticalfa