各国风电并网导则对低电压穿越的要求

2004-12-14,1,2004-12-14,2,迟永宁CHIYongningchiyn并网技术室,各国风电并网导则对低电压穿越的要求为什么需要低电压穿越ComparisonofLVRTrequirementsworldwide-WhydoweneedLVRT?,2009.01.06中国电力科学研究院新能源研究所,大纲Outline,低电压穿越（LVRT）的概念ConceptofLowVoltageRideThrough风电机组低电压穿越的必要性ThenecessityofwindturbinesLVRT各国风电标准对低电压穿越的要求TherequirementonLVRTingridcodeworldwide风电机组低电压穿越的实现方案RealizationofwindturbineLVRT,1、低电压穿越（LVRT）的概念ConceptofLowVoltageRideThrough,什么是低电压穿越？LVRT：LowVoltageRideThrough当电网故障或扰动引起风电场并网点的电压跌落时，在一定电压跌落的范围内，风电机组能够不间断并网运行。Windturbinesshouldstayconnectedtothenetworkandkeepoperationfollowingvoltagedipscausedbyshort-circuitonanyorallphases,wherethevoltagemeasuredattheHVterminalsofthegridconnectedtransformerremainsabovethepredefinedvoltageprofile.也有故障穿越的提法。FRT：FaultRideThrough,低电压穿越（LVRT）的概念ConceptofLowVoltageRideThrough,由于风电机组一般采用异步发电机技术（丹麦概念），电网发生故障时机端电压难以建立，若风电机组继续挂网运行，将会影响到电网电压无法恢复，因此，电网发生故障出现电压跌落时，一般都是采取切除风电机组的方法来处理。InductionmachineisusallyusedinDenmarkConceptWindTurbines,theactiveexcitingcannotbeprovidedby.Thevoltagecannotberecoveredifthewindturbinestillkeepoperatingsothewindturbinemustbetrippedincaseofvoltagedipsduringthegridfault.,低电压穿越（LVRT）的概念ConceptofLowVoltageRideThrough,150MW风电场，基于普通异步发电机的恒速风电机组。三相短路故障持续0.1sWindfarmcapacity150MW.IGbasedwindturbines.3phaseshort-circuitduration100ms,动态电压崩溃DynamicVoltageCallapse,低电压穿越（LVRT）的概念ConceptofLowVoltageRideThrough,风电装机比例较低时：可以允许风电场在电网发生故障及扰动时切除，不会引起严重后果。ThewindpenetrationislowThetripofwindfarm(windtrubine)duringpowergriddisturbancescanbeacceptable.Itsnotabigproblemtothepowersystem.,低电压穿越（LVRT）的概念ConceptofLowVoltageRideThrough,风电装机比例较高时：高风速期间，由于输电网故障引起的大量风电切除会导致系统潮流的大幅变化甚至可能引起大面积的停电，而带来频率的稳定问题。低电压穿越能力是必需的ThewindpenetrationishighLargescalewindfarm(windturbine)trippingwillcauseloadflowchangingviolentlyevenpowersystemblackout.Thefrequecystabilityissueisthemostconcernbecausethepowerlossescouldleadtoinstability.LVRTisnecessary.,低电压穿越（LVRT）的概念ConceptofLowVoltageRideThrough,高风电穿透功率情况下，故障导致的电压跌落更为严重。Voltagedipswillbemoresevereduringhighwindpenetration,风电机组额定运行时HighWind,低电压穿越（LVRT）的概念ConceptofLowVoltageRideThrough,风电机组达到切入风速时LowWind,2008BaiChengPowerGridSingleLineDiagram,低电压穿越（LVRT）的概念ConceptofLowVoltageRideThrough,2004-12-14,12,电网故障电压跌落曲线Voltagedipsunderpowersystemdisturbances,系统中某节点电压跌落的严重程度与此节点距离故障点的电气距离远近此节点固有的无功电压支撑能力风电功率的高低密切相关ThevoltagedipextentofspecificbusbarhavecloselyrelatedwithElectricaldistancetothefaultlocationVoltagesupportcapabilityofthespecificbusbarWindPoweroutput,低电压穿越（LVRT）的概念ConceptofLowVoltageRideThrough,电网发生电压跌落对风电机组的影响机械、电气功率的不平衡影响机组稳定运行暂态过程导致发电机中出现过流，可能损坏器件附加的转矩、应力可能损坏机械部分TheimpactonwindturbineofvoltagedipsUnbanlancetorquemayinfluncethestableoperationofwindturbineOvercurrentofgeneratorintransientmaydamagetheElectronicscomponents.Additionaltorqueorforcesmaydamagethemechanicalcomponents.,低电压穿越（LVRT）的概念ConceptofLowVoltageRideThrough,不同电网中对风电机组低电压穿越能力要求的高低也不太一样。TheLowVoltageRideThroughRequirementstothewindturbinesmaydifferentindifferentpowergrid.,低电压穿越（LVRT）的概念ConceptofLowVoltageRideThrough,2.风电机组低电压穿越的必要性ThenecessityofwindturbinesLVRT,风电机组低电压穿越的必要性ThenecessityofwindturbinesLVRT,目前我国两大类风电机组的特性对比：Characteristicscomparisonofthenormaltwotypesofwindturbines,风电机组低电压穿越的必要性ThenecessityofwindturbinesLVRT,目前我国两大类风电机组的特性对比：Currentstatusofcharacteristicscomparisonofthenormaltwotypesofwindturbines稳态特性：变速风电机组好于恒速风电机组SteadyStateCharacteristics:VariablespeedbetterthanFixedspeed暂态特性：恒速风电机组好于变速风电机组由于变速风电机组转子变频器过流能力差，又无法实现低电压穿越能力。TransientStateCharacteristics:FixedspeedbetterthanVariablespeedReason:over-currentcapabilityofconverterislimited,LVRTcantberealizedatpresent.,基于普通异步发电机的恒速风电机组，由于电压问题无法完成低电压穿越（电网大扰动时）。FixspeedwindturbineequippedwithnormalinductiongeneratorcantrealizetheLowVoltageRideThroughCapabilitybecausethegeneratorterminalvoltagecannotberecoveredafterthelargedisturbancesofthepowergrid(Short-circuit).,风电机组低电压穿越的必要性ThenecessityofwindturbinesLVRT,基于双馈电机的变速风电机组，是否能够实现LVRT？变速风电机组的LVRT功能，受制于电力电子器件自身的过流能力。一般而言，IGBT的过流能力只是额定电流的两倍。现有国产风电机组配备有被动Crow-bar，无法实现LVRT。IftheLVRTcanberealizedbythevariablespeedwindturbinebasedonDFIG?TheLVRTcapabilityofvariablespeedwindturbineislimitedbytheover-currentcapabilityoftheConverter(23timesofratedcurrent)Localizedproductwindturbinesonlyequippedwithpassivecrow-bar,LVRTcantberealizedatpresent.,风电机组低电压穿越的必要性ThenecessityofwindturbinesLVRT,吉林电网风电机组切机情况介绍BriefingoflargescalewindturbinebreakdowninJilin,时间:2008.04.09早晨天气情况:刮风，下小雨。故障位置:白城至开发变66kV线路(19km)，距离白城变2.4km。故障类型:2相短路(B-C)发生时间05:07:54保护动作情况:线路距离保护与过流保护动作2008.04.09morningWindy,smallrain.Faulttype:2phaseshortcircuit(B-C)happenat05:07:54Faultlocation:66kVdistributionlinefromBaichengtoKaifasubstation;2.4kmfarfromBaichengsubstation.Relayactivation:Distancerelayandover-currentrelaytriggered.,吉林电网风电机组切机情况介绍BriefingoflargescalewindturbinebreakdowninJilin,80ms后故障线路三相切除；80-110ms后，洮南大通风电场内所有机组跳闸；120-150ms后，富裕风电场所有风机跳闸；同发龙源、华能场内所有风电机组跳闸；05:07:55重合成功；80mslater,the3phasesoffaultedlinewastripped80-110mslater,allthewindturbinesinTaoNanDatongWindFarmtripped.120-150mslater,allthewindturbinesinFuYu,TongFaLongyuan,TongFaHuanengwindfarmstripped.Re-closedsuccessfullyat05:07:55,Pro-Fault故障前,223MW,232kV,234kV,38Mvar电容器组,55MW,时间:05:07,230kV,Post-Fault故障后,0MW,244kV,251kV,38Mvar电容器组,0MW,时间:05:07,236kV,定速机组,系统调整后Afterregulation,0MW,235kV,237kV,38Mvar电容器组,0MW,控制电压,时间:05:13,风机保护Protectionofwindturbine东汽FD77-1.5MWTransientgriderrorCrowbaractivateGamesaG52GridvoltageerrorStatorbreakeropen,吉林电网风电机组切机情况介绍BriefingoflargescalewindturbinebreakdowninJilin,西北地区风电情况调研investigationofNorthwestarea类似的情况，在甘肃玉门风电场、甘肃安西中广核大梁子风电场、宁夏贺兰山风电场都发生过。电网扰动，不是非常严重带有变频器的风电机组切机恒速风电机组稳定运行ThesimilarcaseswerehappenedinYumen,DaliangziwindfarmsinGansuprovincialpowergrid,HelanshanwindfarminNingxiaprovincialpowergrid.NotseverepowergriddisturbanceTrippingofWindturbineswithconverterFixedspeedwindturbinesarestable,变速风电机组由于变频器对电网故障过于敏感，电网轻微故障会引起机组切除。风电机组都是0s启动切除。风电机组没有低电压穿越功能，当风电装机更大时，电网频率会有问题。Thetrippingofvariablespeedwindturbinecausedbythegriddisturbancesisarisenfromthehighersensitivityofconvertertoover-current.Thewindturbinesaretrippedinstantaneously.HighwindpenetrationwillresultinpowersystemfrequencyproblemsifwindturbineswithoutLVRTcapabilityunderthegriddisturbances.,电网故障大面积风电切机的原因Reasonofwindturbinebreakdown,当风电装机增大时（百万千瓦、千万千瓦风电基地）Windpenetrationishigh(10GWwindpowerbaseputintooperation),-低电压穿越必不可少！其提出主要是基于有功平衡的考虑。Basedonpowerbalancingconsideration,theLVRTrequirementisputforward.,风电机组低电压穿越的必要性ThenecessityofwindturbinesLVRT,3、各国风电标准对低电压穿越的要求TherequirementonLVRTingridcodeworldwide,美国风电场低电压穿越标准（也是AWEA的LVRT要求）LVRTrequirementinUnitedStategridcode,3.1美国低电压穿越要求requirementinUSGridCode,风电场必须具有在电压跌至15%额定电压时能够维持并网运行625ms的低电压穿越能力；风电场电压在发生跌落后3s内能够恢复到额定电压的90时，风电场必须保持并网运行（任何时间，只要电压值不低于图中的电压曲线）。Awindgeneratingplantmusthavelowvoltageride-throughcapabilitydownto15percentoftheratedlinevoltagefor0.625seconds;Awindgeneratingplantmustbeabletooperatecontinuouslyat90percentoftheratedlinevoltage,measuredatthehighvoltagesideofthewindplantsubstationtransformer.,3.1美国低电压穿越要求requirementinUSGridCode,3.2加拿大低电压穿越要求requirementinCanadaGridCode,加拿大LVRT能力规定（Quebec）LVRTrequirementinCanadagridcode,对风电场的LVRT规定，各省各地可以根据实际情况进行相应修改，LVRT在以下情况可以简化：省级规定。系统影响研究表明实际最大容量允许的地方。AreducedrequirementforLVRTmaybesoughtinaccordancewiththefollowing:a)Provincialrules.b)ThefindingsofSystemImpactStudiesdevelopedforthespecificsiteandwhichshowtheactualmaximumcapabilitythatisrequired.Itshouldbenotedthateithera)orb)maydefineareducedrequirementwhichmayinsomecircumstancesbecomenorequirementatall.,3.2加拿大低电压穿越要求requirementinCanadaGridCode,允许LVRT根据实际需要变化，电力系统运营商也应该认可这些变化。TheintentionofthisclauseistoallowtheactualrequiredLVRTcapabilitytobevariedaccordingtorequirements.Variationaccordingtoa)orb)shouldbeagreedwiththesystemoperator.,3.2加拿大低电压穿越要求requirementinCanadaGridCode,3.3德国低电压穿越要求E.onrequirementinGermanyGridCode,2001年之前：德国电网上的风电机组在电网故障时都会切除。2001年：简单的Faultridethrough的要求，实现故障后有功支持。AGO1（AdvancedGridOption1）Vestas解决方案：在定子回路接入电阻，150200ms，无功功率不控制Before2001,windturbinemaytripduringgriddisturbances.At2001:SimpleFaultridethroughforpost-faultactivepoweroutput.AGO1（AdvancedGridOption1）,3.3德国低电压穿越要求E.onrequirementinGermanyGridCode,2003年之后：E.on提出更高要求，Voltagetolerancecurve要求无功电流贡献以控制电压。AGO2（AdvancedGridOption2）风电场本身有无功支撑能力，利于恢复，能够支撑电压。After2003MorerequirementswereaskedbyE.on.ReactivecurrentisrequiredtocontributeforvoltagecontrolAGO2Windfarmreactivepowercapabilityisrequiredtosuppurtthevoltagerestore.,德国LVRT能力规定（高短路电流）LVRTrequirementforHighshort-circuitcurrent,3.3德国低电压穿越要求E.onrequirementinGermanyGridCode,3.3德国低电压穿越要求E.onrequirementinGermanyGridCode,德国LVRT能力规定（低短路电流）LVRTrequirementforlowshort-circuitcurrent,有功输出在故障切除后立即恢复并且每秒钟至少增加额定功率的20%。阴影区域中，有功功率每秒钟可以增加额定功率的5%。Activepoweroutputmustresumeimmediatelyfollowingfaultclearingandbeincreasedwithagradientofatleast20%oftheratedpowerpersecond.Withintheshadedareatheactivepowerincreasecantakeplaceat5%oftheratedpowerpersecond.,3.3德国低电压穿越要求E.onrequirementinGermanyGridCode,网络故障时，机组必须能够提供电压支持。如果电压降落幅度大于机端电压均方根值的10%，机组必须切换至支持电压。机组必须在故障识别后20ms内通过提供机端无功功率进行电压支持，无功功率的提供必须保证电压每降落1%的同时无功电流增加2%。Withadisturbednetworkthegeneratingunitsmustsupportthevoltage.Ifavoltagedropofmorethan10%oftherootmeansquare(r.m.s.)ofthegeneratorterminalvoltageoccursthegenerationunitmustbeswitchedovertovoltagesupport.Thesupportofthenetworkvoltagemustbeprovidedwithin20msafterfaultidentificationbyprovidingreactivepoweratthegeneratorterminalswithafactorof2%oftheratedcurrentperpercentofthevoltagedrop.Switchingbackfromvoltagecontroltonormaloperationispossibleafter3seconds.,3.3德国低电压穿越要求E.onrequirementinGermanyGridCode,3.4丹麦低电压穿越要求EltrarequirementinDenmarkGridCode,双重电压降落特性是丹麦并网要求的一部分。它要求两相短路100ms后间隔300ms再发生一次新的100ms短路时不发生切机。单相短路100ms后间隔1s再发生一次新的100ms电压降落时要求也不发生切机。Thedouble-dipfeatureisapartoftheDanishrequirementswhichrequiresnodisconnectionforatwo-phasedshortcircuitin100ms,followedin300msbyanewshortcircuitof100ms.Alsonodisconnectionmayoccurforasinglephasefaultin100msfollowedin1sbyanother100msvoltagedip.,3.4丹麦低电压穿越要求EltrarequirementinDenmarkGridCode,3.4丹麦低电压穿越要求EltrarequirementinDenmarkGridCode,丹麦LVRT能力规定LVRTrequirementinDenmarkGridCode,故障穿越要求规定，三相故障从标称电压的2075%开始，持续10s。Athree-phasefaultisspecifiedbyaFaultRideThoughcurefrom2075%ofnominalvoltagein10sec.风电场应在电压重新到达0.9pu以上后，不迟于10s发出额定功率。Thewindfarmshallproducetheratedpowernolaterthan10s.afterthevoltageisabove0.9p.uagain.,3.4丹麦低电压穿越要求EltrarequirementinDenmarkGridCode,在电压恢复到0.9pu后，应在不迟于10s内满足与电网的无功功率交换要求。电压降落期间，风电场必须尽量发到风电场标称电流1.0倍的无功电流。Exchangeofreactivepowerwiththegridshallmeettherequirementinnolaterthan10s.afterthevoltageisabove0.9p.uagain.Duringthevoltagedipthewindfarmmustasamaximumtakeareactivecurrentcorrespondingto1.0timesthenominalcurrentofthewindfarm.,3.4丹麦低电压穿越要求EltrarequirementinDenmarkGridCode,4、风电机组低电压穿越的实现方案RealizationofwindturbineLVRT,保护转子过流，保护变频器。（Crow-bar）降低机械转矩，保证机组稳定运行，不发生功率振荡。（桨距角控制）ProtectionConverterprotectiontoavoidthedamagecausedbyover-current.(Crow-bar)Decreasingthemechanicaltorquetostabilizethewindturbineoperation.(PitchControl),4.1需解决的问题Problems,支撑动态发出无功功率，支撑电网电压。（动态无功）尽快恢复电气有功出力。（有功控制）SupportReactivepowercontroltosupportthegridvoltage(Dynamicreactivepowercontribution)Activepowercontroltorestorethepoweroutput(Activepowercontrol),4.1需解决的问题Problems,双馈变速机组的Crow-barresistance解决方案只是旁路转子变流器，定子侧变流器仍挂网运行。Crow-bar动作期间，成为普通的异步机。Crow-barresistancesolutionofDFIGbasedwindturbinesBypasstherotorsideconverter,gridsideconverterstillinoperation.BehavingasthenormalinductionmachineduringtheactivationofCrow-bar.,4.2几种常见的解决方案Somenormalsolutions,双馈变速机组的Crow-barresistance解决方案Crow-bar短接时间很短，6080ms；Crow-bar的电阻可以阻尼转子磁链，当转子磁链衰减后就可以退出，此时稳态短路电流已不是很大。Crow-bar退出后，变频器重新同步，控制能力恢复。Crow-barresistancesolutionofDFIGbasedwindturbinesDurationofCrow-baractivationlasting60-80ms.Theresistanceofcrow-bardampingtherotorfluxandcrow-baroutofservicewhentherotorfluxdeclines.Afterthecrow-baroutofservice,theconverterwillbere-synchronousandrestoringthecontrollability.,4.2几种常见的解决方案Somenormalsolutions,典型Crow-bar控制电路TypicalCrow-barcontrolcircuit,4.2几种常见的解决方案Somenormalsolutions,DFIG,RotorSideConverter,双馈变速机组的FastReconnection解决方案Nordex的双馈变速风电机组采用此种方案也采用Crow-bar保护，但是Crow-bar可以做得较小。FastReconnectionsolutionofDFIGbasedwindturbinesNordexsolutionforLVRTCrow-barprotectionalsousedbutwithsmallercapacity.,4.2几种常见的解决方案Somenormalsolutions,双馈变速机组的FastReconnection解决方案100ms内切除风电机组，Crow-bar也动作。100ms后，风电机组再次并网，同时Crow-bar退出，风电机组重新运行。FastReconnectionsolutionofDFIGbasedwindturbinesCutoffthewindturbinein100mswithcrow-baractivation.Reconnectedthewindturbine100mslater,deactivatethecrow-barandre-operatethewindturbine.,4.2几种常见的解决方案Somenormalsolutions,双馈变速机组的ChopperResistance解决方案VESTAS机组采用此种方案采用大容量二极管与标准IGBT并联。ChopperResistancesolutionofDFIGbasedwindturbinesBeadoptedbyVestaswindturbinesLargecapacitydiodeparallelingwiththestandardIGBT,4.2几种常见的解决方案Somenormalsolutions,双馈变速机组的ChopperResistance解决方案ChopperResistancesolutionofDFIGbasedwindturbines,4.2几种常见的解决方案Somenormalsolutions,双馈变速机组的ChopperResistance解决方案故障过程中，IGBT闭锁，二极管导通，短路引起的冲击电流经二极管流过，用二极管导通大的暂态过电流以保护IGBT。导致DC-Link的电容电压升高，采用chopperresistance，消耗电容的充电功率。ChopperResistancesolutionofDFIGbasedwindturbinesTheimpulsioncurrentcirculatingthroughthediodetoprotecttheIGBTfromdamageduringthefault.ThevoltageofDC-Linkwillbechargedtoahighlevel,thechopperresistanceburningalltheenergy.,4.2几种常见的解决方案Somenormalsolutions,此三种解决方案都会导致风电场在短时间内失去控制能力ControllabilitywillbelostduringtheLVRTfunctionactivated,4.2几种常见的解决方案Somenormalsolutions,4.3恒速机组低电压穿越能力的实现RealizationofLVRToffixedspeedwindturbine,无电力电子设备，定、转子有一定过流能力。机端电压重建（VoltageRestore）与机组特性、电网坚强程度有关。Acertainover-currentcapabilityofthestatorandrotorofnormalinductiongeneratorTerminalvoltagerestoredependsonthegeneratorbehavioraswellasthestrengthofthepowergrid.,150MW风电场，基于普通异步发电机的恒速