TransientOver-Voltage(TOV)andItsSuppressionForaLargeWindFarmUtilityInterconnectionChongHan*,Member,IEEE,DonE.Martin*,Member,IEEE,andModestoR.Lezama**,Member,IEEE*GridSystemConsulting,ABBInc,Raleigh,NorthCarolina,USA**BPWindEnergy,Houston,Texas,USAAbstract—Recently,renewablewindenergyisenjoyingalargewindfarm(300MW).TwodifferenttypesofWTGs,boominggrowthgloballytobecomeanimportantgreenwhichareafixedspeedsquirrelcageinductiongeneratorelectricitysourcetoreplacefossilfuels.Differentfromaclassical(SCIG)andafull-scaleBtB-VSC-basedWTG,werestudied.generationplantconsistingofsynchronousgenerators,largeTwoGSUtransformerconfigurations,Δ/Yg(Δonhighside)windfarmsaretypicallymadeupofmanywindturbinegenerators(WTGs)rateduptoseveral-MWssofarandorYg/Yg,wereanalyzed.TwoTOVsuppressionmethods,connectedthroughundergroundcablesinageographicalterrain.whicharethegroundingtransformerandfastgroundingThetypesofWTGsarediversified,whichcanbeafixed-speedswitch,wereevaluated.Theperformanceandsignificanceofinductiongenerator,avariable-speedinductiongenerator,aTOVsuppressionmethodsweredemonstrated.Thefeasibilitydouble-fedinductiongenerator(DFIG),orafull-scaleback-to-usingCOG(coefficientofgrounding)analysismethodforback(BtB)AC-DC-ACVSC-connected(voltagesourcerenewablewindgenerationgroundingdesignisdiscussed.converter)WTG.Thesecombineduniquecharacteristicsofawindfarmcanbepotentialfactorsforover-voltageswhichcancausesurgearrestersandequipmentfailurewithinawindfarm.II.SYSTEMDESCRIPTIONANDMODELDEVELOPMENTInthepaper,aninvestigationoftransientover-voltagesInthissection,thewindfarmsystemdescriptionand(TOV)duringwindfarmswitchingeventsandtheimpactofmodeling,andPSCADTMmodeldevelopmentarepresented.generatorstep-uptransformer(GSU)configurationandsolutionstosuppresstheTOVduringtheseeventswasconductedonaA.WindFarmwithFix-SpeedWTGslargewindfarm(300MW).TwodifferenttypesofWTGs,whichFig.1showsthecollectorsystemone-linediagramfortheareafixedspeedsquirrelcageinductiongenerator(SCIG)andafull-s