Novel Power Electronics Systems for Wind Energy

October2004•NREL/SR-500-33396R.Erickson,S.Angkititrakul,O.Al-Naseem,andG.LujanUniversityofColoradoBoulder,ColoradoNovelPowerElectronicsSystemsforWindEnergyApplications:FinalReportPeriodofPerformance:August24,1999–November30,2002NationalRenewableEnergyLaboratory1617ColeBoulevard,Golden,Colorado80401-3393303-275-3000••BattelleContractNo.DE-AC36-99-GO10337October2004•NREL/SR-500-33396NovelPowerElectronicsSystemsforWindEnergyApplications:FinalReportPeriodofPerformance:August24,1999–November30,2002R.Erickson,S.Angkititrakul,O.Al-Naseem,andG.LujanUniversityofColoradoBoulder,ColoradoNRELTechnicalMonitor:A.LaxsonPreparedunderSubcontractNo.XCX-9-29204-01NationalRenewableEnergyLaboratory1617ColeBoulevard,Golden,Colorado80401-3393303-275-3000••BattelleContractNo.DE-AC36-99-GO10337NOTICEThisreportwaspreparedasanaccountofworksponsoredbyanagencyoftheUnitedStatesgovernment.NeithertheUnitedStatesgovernmentnoranyagencythereof,noranyoftheiremployees,makesanywarranty,expressorimplied,orassumesanylegalliabilityorresponsibilityfortheaccuracy,completeness,orusefulnessofanyinformation,apparatus,product,orprocessdisclosed,orrepresentsthatitsusewouldnotinfringeprivatelyownedrights.Referencehereintoanyspecificcommercialproduct,process,orservicebytradename,trademark,manufacturer,orotherwisedoesnotnecessarilyconstituteorimplyitsendorsement,recommendation,orfavoringbytheUnitedStatesgovernmentoranyagencythereof.TheviewsandopinionsofauthorsexpressedhereindonotnecessarilystateorreflectthoseoftheUnitedStatesgovernmentoranyagencythereof.Availableelectronicallyat:U.S.DepartmentofEnergyOfficeofScientificandTechnicalInformationP.O.Box62OakRidge,TN37831-0062phone:[phone]fax:[phone]email:mailto:[e-mail]public,inpaper,from:U.S.DepartmentofCommerceNationalTechnicalInformationService5285PortRoyalRoadSpringfield,VA22161phone:[phone]fax:[phone]email:[e-mail]:(therebyimprovingefficiencyatbothfullloadandpartialload),anditreducessizeoffilterinductors.Althoughthemajordisadvantagesofmultilevelconversionarethecomplexityofitscontrolanditsbusbarinterconnections,theseissuescanbeaddressedusingongoingadvancesinmicroprocessortechnology.Attemptsbyotherauthorstoaddressthecomplexityofpowerinterconnectionsandbusbarconstructionhavebeenlargelyunsuccessfulorlimitedinapplication.Wehaveaddressedthisissuebyproposinganewfamilyofmultilevelmatrixconvertersthataremodularindesign,requiresimplepowerinterconnectionsandbusbarconfigurations,andexhibithighefficiencyandgoodsemiconductorswitchutilization.Webelievethatthisapproachiswell-suitedtothevariable-speedwindpowerapplication,whereitcanimprovethecostofenergy,andthatitcanbescaledtohighervoltageandpowerlevels.Theproposedconvertersarefundamentallydifferentfromknownmatrixconverters,aswellasfromknownmultilevelconverters,buttheycombinethepositivefeaturesofboth.Wehaveusedsimulationtoconfirmthesuccessfuloperationofthebasicconfigurationoftheproposednewconverters.Atfirst,controllingtheproposedconvertersappearstobequitecomplexanddaunting.Butwehavealsoderivedanewcontrolalgorithm—single-capacitorspacevectormodulation—thatisrelativelysimpletoapplyandunderstand.Thisapproachis,insomesense,optimal,inthatitminimizesthecirculatingcurrentsbetweencapacitors,allowingtheconvertertooperatewithrelativelyhighdirectpower(leadingtolowconductionandswitchingloss).Usingspacevectormodulationleadstocompatibilitywithfield-orientedcontrol.WebelievethatthisapproachalsoallowstheissueofcontrolofDCcapacitorvoltagelevelstobeaddressedinare