Modelling-and-Simulation-of-Doubly-Fed-Induction-W

ModellingandSimulationofDoubly-FedInductionWindPowerSystemBasedonMatlab/SimulinkZhenSun*,HongyuWang†,YingLi†*†SchoolofElectricalandElectronicEngineering,NorthChinaElectricPowerUniversity,Beijing,102206,China*Email:[e-mail]:windpower,doubly-fedinductiongenerator(DFIG),vectorcontrol,S-Function.AbstractDoubly-fedinductiongenerator(DFIG)hasbecomethemostwidelyappliedwindturbineinvariablespeedconstantfrequency(VSCF)windpowergeneration,sinceitpresentsmanyadvantagessuchasvariablespeedrunning,thedecoupledcontrolofactiveandreactivepower,andthesmallrotatedifferencepower.Targetingthedoubly-fedwindpowersystem,thispaperestablishestheoverallmathematicalmodelcomposedofwindturbine,drivesystem,double-fedinductiongenerator,statorfluxorientationvectorcontroltactics,maximumpowerpointtrackingtactics.Basedonthemathematicalmodelmentionedabove,thepaperwritestheS-FunctionproceduresofthedifferentwindcircumstanceswithMatlab/Simulinktosetupadouble-fedwindpowersystemsimulationmodel.Andalsotakingtwostep-upwindspeedsasexamples,simulationstudiesaremadeonthedynamiccharacteristicsofthemodelwiththegridconnected.Thesimulationstudiesshowthatthemodelrealizesthemaximumpowerpointtrackinganddecouplingcontrolofpower,andthedouble-fedwindpowersystemhassatisfactorydynamiccharacteristics,thusprovingthatthemodelestablishediscorrectandvalid.1IntroductionWindpowerhasbeendevelopingrapidlyintheworld,thedoubly-fedwindturbineismainlyaformwhichisshowninFig.1.Thestatorofdoubly-fedinductionmotorisdirectlyconnectedtothegrid,therotortothegridthroughthebi-directionalinverter.Thestructurehashigherwindenergyutilizationefficiencythanthefixed-bladeawayfromthestallturbinesandrotorexcitingmaketherequiredinvertercapacityonlypartoftheunitratedpower.Thesecangreatlyreducethecost,realizeactiveandreactivepowercontrol,andplaytheroleofreactivecompensationonthegrid.Adjustingthebladepitchanglemayalsochangetheaerodynamiccharacteristicsofwindturbinepitchsystemsandthentheunitcontrolmethodismoreflexible.Forthesereasons,thedoubly-fedwindturbinehasbeenwidelypromoted[1,2].Inthispaper,themathematicalmodelofthedoubly-fedinductiongeneratorisderivedindetailandthemathematicalmodelofthecoordinatesystemisgiven.Byvectorcontroltechnologyofthestatorfluxoriented(SFO),thecontrolequationisderivedtoachievedecouplingcontrolofpower.Thelargestwindenergycapturemethodbasedonthereferenceactivepowerisalsodiscussedinthecaseoffixedpitch,andsimulationmodelofdoubly-fedwindpowergenerationsystemisestablishedbasedonMatlab/Simulinkplatform.Fig.1SchematicdiagramofDoubly-fedwindpowergenerationsystem2Mathematicmodelofdoubly-fedwindturbine2.1MathematicmodelofwindturbineThemechanicalinputtorqueofwindturbinewTandwindspeedwVisobtainedbyaerodynamics[3]asfollows32,2WpWRVCTUSTOO(1)WWRVZO(2)where,Uisairdensity;Risradiusofwindturbineblades;Tisthepitchangleofblade;Oistipratio;pCiswindenergyutilizationfactor;wZisspeedofblade.pCisprovidedbythemanufactures,theempiricalformulafor12.5,0.22116/0.45pCeETOET(3)where,310.0351/0.081EOTT§·¨¸©¹.Windenergyutilizationcoefficient-tipratioisshowninFig.2.Foragivenbladepitchangle,differentwindenergyutilizationcoefficientscorrespondingtodifferenttipspeedratiohavelargerdifference,andonlythefixedoptimumtipspeedratiocanmakewindenergyutilizationfactorreachitsmaximum.Fromtheequation(2),itmustmakethemechanicalspeedofwindturbinewZchangewhenwindspeedvariestomaintainoptimumtipspeedratio,onlymaintaintheoptimumtipspeedratiocanensurethemaximumwindenergycapture.Fig.2Windenergyutilizationcoefficient–tipratio2.2Mathematicalmodelofdoubly-fedinductiongeneratorVoltageequationofstatorwinding11sdssdsdsqsqssqsqsduRipuRip\Z\\Z\­®¯(4)VoltageequationofrotorwindingrdrrdrdsrqrqrrqrqsrduRipuRip\Z\\Z\­®¯(5)FluxequationofstatorwindingsdssdmrdsqssqmrqLiLiLiLi\\­®¯(6)FluxequationofrotorwindingrdrrdmsdrqrrqmsqLiLiLiLi\\­®¯(7)Torqueequation()()ensqsdsdsqnmsdrqsqrdTpiipLiiii\\Where,“s”and“r”isrespectivelythestatorandtherotor.sdu,squ,rdu,rquisrespectivelytheinstantaneousvoltagevalueofthed-axisandq-axisofthestatorandrotor;sdi,sqi,rdi,rqiisrespectivelytheinstantaneouscurrentvalueofthed-axisandq-axisofthestatorandrotor˗sd\,sq\,rd\,rq\isrespectivelythefluxofthed-axisandq-axisofthestatorandrotor;sR,rRisrespectivelytheequivalentresistanceofthestatorandrotorwinding;1srZZZ;mLismutualinductanceofthestatorandrotorwindingsofcoaxialhinge;sListheself-inductanceofstatorwinding;rListheself-inductanceofrotorwinding[4-6].2.3Theprincipleofstatorflux-orientedcontrolThestatorfluxorientationreferstothed-axissynchronousrotatingdqcoordinatesystemorientedinthedirectionofthedoubly-fedmotorstatorflux,showninFig.3.Wecanobtainthefollowingrelationship:,0sdssq\\\,where,s\istheamplitudeoffluxvector~s\.IgnoringtheresistanceofthestatorwindingsR,thevoltagevectorofstatorwinding~sUwilllagfluxvector~s\90°spatialelectricalangle,then0,sdsqsuuU.sUistheamplitudeofvoltagevectorofstator~sU.Theseconditionsaresubstitutedintotheformula(4)~(7),thefollowingwillbeavailable:()()()rrdrdsrqrrqrqrdmrqssrdsuRipiiRipiLuLiVZVVZ\V˜­°®