风力异步电动机

第第页风力异步电动机毕业论文,开题报告。

外文翻译

2MW风力双馈异步电动机的讨论设计

指导老师：盛光忠

同学：安梓铭

〔三峡高校科技学院〕

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这个变量速度范围是成正比的评级的转子等通过变频器调速范围30%[4、5、6、7]转子转换器只需要的DFIG总量的30%的能量而使全面掌握完整的发电机输出功率。这可能导致显著的成本节约了转子转换器[4]。滑动环连接,但需要保持转子绕组,性能安全牢靠。电源发电机速度特性,如图1所示为2MWwind汽轮机。对于一个商业发电机速度随风速,然而这种关系是为某一特定地点。作为风速,并因此机速度快、输出功率下降了的风力发电机减削直至关闭时提取风是比损失的发电机和液力变矩器。操作模式已经提出,风力机制造商宣称延伸速度范围以便在较低的速度能量提取的风是比损失在系统等系统能保持联系。这个建议标准的双(DF)连接在正常运用调速范围所谓DF异步发电机(“模式是用来延长低速运行。原先的工作已经显示了IG模式能够运作的DFIG滑到80%[8]。这一改变在运行时实现定子从电网DF模式,然后短巡回定子使国际组操作。全部的发电机组转子变频器在流经IG模式。免疫球蛋白曲线相同的曲线为30%DF滑动。估量国际组电力提取的风在低速下所获得的曲线,推断DF模式。参考扭矩由掌握器(DF和IG模式),就可以很简单地来源于这样的曲线。扭矩-速度数据可以存储在一个查表所以参考转矩和转速改变自动。

这个技能的现代DF风力涡轮机不同的无功功率汲取或产生[6、第九条、第十条]让风涡轮参加无功功率平衡的格子里。无功功率在电网的连接中描述的工作,由英国,连接条件小节CC.6.3.2[11]从国家电网。无功要求风电场的定义是由图2。

MVAr点——相当于功率因数为0.95领先于额定兆瓦

MVArB点——相当于功率因数为0.95滞后于额定兆瓦

C-MVAr5点的额定兆瓦

D点-MVAr5%额定兆瓦

E-MVAr12点的额定兆瓦

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方式,在DF)的方式显示指定。配置程序做了具体的分析,形成了转子的电压在整个操作范围内DFIG模式,给出了这种能够主宰成分浮出水面。这是特别重要的先进掌握方案设计时充分概论的工作范围内,能被确认。仿真模型,它已经被证明对

7.5kW试验室钻机[12],是应用于现实的2千瓦风力使结论是关于拟议中的运用IG模式在真实的风力涡轮。

2、连接方法

双馈异步电机通常连接如图3。GSI网格侧逆变器(保持)是一个固定的直流环节电压与给定的功率因数的网格(在我们的状况下,团结)。转子侧逆变器(劳损)的掌握,从而使最大能量提取的动能的风而使定子功率因数掌握范围内统一要求,尽管网格的功率因数往往是可取的。另一种连接方式为双馈电机如图4,这叫了异步发电机(指定)连接。定子是脱离电网和短路。转子回路图3。从不变。GSI一样的掌握方式。DF)目的是为了掌握劳损定子磁链在汲取最大功率的动能,风能。

3、掌握器性能

闭环掌握方式都和IG模式DF争论的前期预备工作[12]但只有一个7.5亿千

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瓦试验室试验平台。2千瓦动力学系统会有所不同,本文争论了。动态掌握器的性能和IG模式为DF中显示的是这段2MW风力涡轮机。

3.1DFIG模式(T和Q掌握)

参考价值的扭矩模式掌握器DF(见图1)和定子无功使网格代码要求达到

[11],图2。

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子)的速度如图7。

稳态Te标称值处理的速度、320海里为400转速和4081海里,源自公元1420年转图1。一个启动顺次需要建立在额定λsr机器,对于一个给定的速度,通过一段斜坡,图7,机器可以产生电力。

一旦该掌握器参考λsr已建立了机械,特*增加通过掌握的名义价值斜坡给定的速度,然后一阶跃响应50海里在400转速与200海里时转速适用。公元1420年,该掌握器掌握机器来跟踪Te*果真,参看图7。

矢量掌握回路的确定值的参考转子电流如图8。最初的成分快速上升到建立λsr,大约三倍公称稳态值对于一个给定的负荷点。当前在额定的限制。最初的解码器能够显著降低,假如一个较慢的反应λsr实现。

这个硬中断恳求优先级别组成,是由扭矩环使渴望权力产生。最初有稍微的误差影响高解码器的交叉耦合正交循环系统的条款。一旦名义λsr于机器径直和正交环路的解耦。又一特步引起短暂飙升的硬中断恳求优先级别*虽然被调谐到这个改变是慢于参考价值。

4、转子的电压元件

双方的性能和IG模式DF已经在上一节。两者都是基于内部掌握电流环和外部掌握回路为转矩和定子无功功率损耗的案例和转矩和定子磁链的IG。再加上解耦方程的PI掌握器的影响,降低产量之间的交叉耦合循环。最末一部分工作的讨论做出贡献的稳态组件的转子电压,全部在方程式(1和2),2千瓦机器来评估的重要性,在不同的速度方程式解耦。转子电压、工具、转子电流、国税局,居于

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万物的工具和组件由方程式(1和2)进行了DF转速范围内(1000年到1950年转矩确定)的正常从图表1),和定子动力因素、pfs、范围的0.9落后领先到0.9%。只有pfs被视为GSI可能保持团结酚醛风轮变频器连接到网格的独立的劳损。

图9所示的是改变的速度和vrdqs定子无功功率范围的调查。vrds组件的主导的稳态的ωsfσirqs的压降和λsq后被忽视的是零组件选择参考帧。这可以比较图9和数字。在一个2千瓦的vrqs机床主导下的ωsf(Lm/Ls)λsd期限为低的总泄漏,降低电感、σirds交叉耦合效应的术语和λs取向的λsq构件框架设置为零。在vrqs改变在恒定的速度(并因此转矩)是由于从irds交叉耦合的定子无功功率调整,Qs,因此pfs这个工具vrqs统治级的组件和对称1500rpm;thesynchronous速度4-pole机。这是经公园等[13]。

在稳态改变径直,irds、正交、irqs、转子电流部件对速度和Qs如图10。irds元件的功率因数、调整定子无,通过掌握Qs和太少

s组件调整。irds确定的价值的比例提供发电机无功功率的定子和转子回路。irds增加越来越积极的比例从转子回路Q同时减削了问从出口到Q的静定。越来越消极irds增加问从,减削了定子电路的转子的一面,直到Q是由转子出口。Qs随维持抱负Te,因此irds组件无会持续pfs在更高的速度。大致上是恒定的irqs元件恒速恒转矩的能量,积极为产生的定位框架和径直和正交轴排成一线国税局的大小是为全部的额定内部条件图10。

其余的这部分说明白转子的电压,vrdqs、稳态部件从方程式(1和2)。这个Rrsirds术语及术语vrdsRrsirqsvrqs仅仅是irdqs,如图10,攀登通过后,所以不显示。

jσωsfirdqs的交叉耦合条件vrdqs如图11所示，jσωsfirdqs有助于vrds和σωsfirds从vrqs。Σωsfirds由组成随既速度和定子无功功率为定子无功成正比,与转矩对于一个给定的定子动力因素。σωsfirds随着年龄的增长而增长速度的组件负载力矩增加如图1。σωsfirqs组件是主导学期在vrds组成eqn(1),在不同步性的速度。在极性的结果ωsf定义和大小的扭矩。irdqs

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大小是由频率上升而上升，ωsf与总漏电感。图12说明vrdqs由j(Lm/Ls)和ωsf和λsdq组成，(Lm/Ls)ωsfλsq有助于vrds，这个学期大致上是零因定位框架。(Lm/Ls)ωsfλsd抑制vrqs的组成，(Lm/Ls)ωsfλsd的外形组成完全由ωsf.决断。

5、争论

分析vrds和vrqs组成的可行性是由占统治地位的条款。λs定位框架的结果λsq和vrds前馈术语被忽视所以稳态vrds组件的结果是Rrsirdsσωsfirqs。三种迥乎不同的区域,然后可以识别sub-synchronous速度，关于同步速度，和超同步速度。vrds的瞬态响应的对于一个步骤irds*主导下的pσirds.p(Lm/Ls)λsd作为一个不足挂齿的效果了λsd术语是恒定的,假设一个僵硬的网格。irds*的脉冲一步稳态值影响的vrqs在vrds的稳态条款，vrqs稳定的状态是由主导下的λsd期限，Vrqs的瞬态响应由irqs*来的是由pσirqs周期正如步骤irqs最初是高的。p(Lm/Ls)λsq有一个最大的作用时λsq约等于零，在vrqs的vrds周期和步骤周期全部的阅历值改变的irqs*。

6、结论

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外文原文

DesignStudyofDoubly-FedInductionGenerators

fora2MWWindTurbine

ABSTRACT

Adesignstudyfora2MWcommercialwindturbineispresentedtoillustratetwoconnectionmethodsforastandarddoubly-fedinductionmachinewhichcane*tendthelowspeedrangedownto80%slipwithoutanincreaseintheratingofthepowerelectronicconverter.Thisfare*ceedsthenormal30%lowerlimit.Thelowspeedconnectionisknownasinductiongeneratormodeandthemachineisoperatedwithashortcircuitedstatorwindingwithallpowerflowbeingthroughtherotorcircuit.AtwoloopcascadedPIcontrolschemehasbeendesignedandtunedforeachmode.The

purposeofthispaperistopresentsimulationresultswhichillustratethedynamicperformanceofthecontrollerforbothdoubly-fedinductiongeneratorconnectionmethodsfora2MWwindturbine.Asimpleanalysisoftherotorvoltageforthedoubly-fedconnectionmethodisincludedasthisdemonstratesthedominantcomponentsthatneedtobeconsideredwhendesigningsuchadvancedcontrolstrategies.

Keywords:Doubly-fed,Inductiongenerator,Windturbine

1.INTRODUCTION

Thereiscontinuinginterestinwindturbines,especiallythosewitharatedpowerofmanymegawatts.This

popularityislargelydrivenbybothenvironmentalconcernsandalsotheavailabilityoffossilfuels.Legislationtoencouragethereductionofthesocalledcarbonfootprintiscurrentlyinplaceandsointerestinrenewablesis

currentlyhigh.Windturbinesarestillviewedasawellestablishedtechnologythathasdevelopedfromfi*edspeedwindturbinestothenowpopularvariablespeedtechnologybasedondoubly-fedinductiongenerators(DFIGs).ADFIGwindturbineisvariablespeedwiththerotorconverterbeingcontrolledsothattherotorvoltagephaseandmagnitudeisadjustedtomaintaintheoptimumtorqueandthenecessarystatorpowerfactor[1,2,3].DFIGtechnologyiscurrentlywelldevelopedandiscommonlyusedinwindturbines.ThestatorofaDFIGisdirectlyconnectedtothegridwithapowerelectronicrotorconverterutilisedbetweentherotorwindingandthegrid.Thevariablespeedrangeisproportionaltotheratingoftherotorconverterandsobylimitingthespeedrangeto30%

[4,5,6,7]therotorconverterneedonlyberatedfor30%ofthetotalDFIGpowerwhilstenablingfullcontroloverthefullgeneratoroutputpower.Thiscanresultinsignificantcostsavingsfortherotorconverter[4].Theslipringconnectiontotherotorwindinghowevermustbemaintainedforreliableperformance.

Thepower–generatorspeedcharacteristicshowninfigure1isforacommercial2MWwindturbine.Thegeneratorspeedvarieswithwindspeedhoweverthisrelationissetforaspecificlocation.Aswindspeed,andthereforemachinespeed,fallsthepoweroutputofthegeneratorreducesuntilthewindturbineisswitchedoffwhenthepowere*tractedfromthewindislessthanthelossesofthegeneratorandconverter.Anoperatingmodehasbeenproposedbyawindturbinemanufacturerthatisclaimedtoe*tendthespeedrangesothatatlowerspeedthepowere*tractedfromthewindisgreaterthanthelossesinthesystemandsothesystemcanremainconnected.Thisproposedthatthestandarddoubly-fed(DF)connectionisusedoverthenormalDFspeedrangeandthe

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so-calledinductiongenerator(IG)modeisusedtoe*tendthelowspeedoperation.PreviousworkhasillustratedthatIGmodeenablestheDFIGtooperatedownto80%slip[8].Thischangeinoperationisachievedby

disconnectingthestatorfromthegridinDFmodeandthenshortcircuitingthestatortoenableIGoperation.AllofthegeneratorpowerflowsthroughtherotorconverterinIGmode.TheIGcurveisidenticaltotheDFcurvefor30%slip.TheestimatedIGpowere*tractedfromthewindatlowspeedsisobtainedbye*trapolatingthecurvefortheDFmode.

Thereferencetorquerequiredbybothcontrollers(DFandIGmode)caneasilybederivedfromthiscurve.Thetorque–speeddatacanthenbestoredinalook-uptablesothereferencetorqueisautomaticallyvariedwithspeed.ThecapabilityofmodernDFwindturbinestovarythereactivepowerabsorbedorgenerated[6,9,10]allowsawindturbinetoparticipateinthereactivepowerbalanceofthegrid.Thereactivepoweratthegridconnectionconsideredinthisworkisdescribed,fortheUK,bytheConnectionConditionsSectionCC.6.3.2[11]availablefromtheNationalGrid.Thereactivepowerrequirementforawindfarmisdefinedbyfigure2.

PointA-MVArequivalentfor0.95leadingpowerfactoratratedMW

PointB-MVArequivalentfor0.95laggingpowerfactoratratedMW

PointC-MVAr-5%ofratedMW

PointD-MVAr5%ofratedMW

PointE-MVAr-12%ofratedMW

TheobjectiveofthispaperistoinvestigatethecontrollerperformanceofDFandIGmodefora2MW,690V,4-poleDFIGusingmachineparametersprovidedbythemanufacturer.Thisisfurtherresearchbuildingona

previouspaperwhichdemonstratedthesteady-stateperformanceofthetwomodesofoperation,DFandIGmode

[8].In[8]theauthorsdiscussedthesteady-stateefficiencyforbothconnections.Thesteady-stateperformanceworkillustratedthattherewerebenefitstooperatingthemachineinoneconnectionmethodasopposedtotheother.

Thispapere*aminesthecontrollability(i.e.transientperformance)ofthe2MWwindturbine.Resultsofthefulldynamiccontroller(currentregulation,decouplingequationsandvectorcontrol)inbothDFmodeandIGmodeareshown.AdetailedanalysisofthecomponentsthatformtherotorvoltageoverthefulloperatingrangeinDFIGmodeispresentedasthisenablesthedominantcontrolcomponentstobeidentified.Thisisparticularlyimportantwhendesigningadvancedcontrolschemesasanoverviewoverthefulloperatingrangecanbeidentified.

Simulationmodels,whichhavebeenvalidatedagainsta7.5kWlaboratoryrig[12],areappliedtoarealistic2MWwindturbinetoenableconclusionstobemaderegardingtheproposeduseofIGmodeinarealwindturbine

2.CONNECTIONMETHODS

Doubly-fedinductionmachinesarecommonlyconnectedasshowninfigure3.Thegridsideinverter(GSI)iscontrolledtomaintainafi*eddclinkvoltagewithagivenpowerfactoratthegrid(inourcaseunity).Therotorsideinverter(RSI)iscontrolledsothema*imumenergyise*tractedfromthekineticenergyofthewindwhilstenablingthestatorpowerfactortobecontrolledwithinthelimitsofthegridrequirementsthoughunitypowerfactorisoftendesirable.

Analternativeconnectionmethodforadoubly-fedmachineisshowninfigure4,herecalledtheinductiongenerator(IG)connection.Thestatorisdisconnectedfromthegridandisshort-circuited.Therotorcircuitisunchangedfromfigure3.TheGSIiscontrolledasinDFmode.TheobjectiveoftheRSIistocontrolthestatorflu*linkagewhilee*tractingthema*imumpowerfromthekineticwindenergy.

3.CONTROLLERPERFORMANCE

AclosedloopcontrollerforbothDFmodeandIGmodehasbeendiscussedinpriorwork[12]butonlyfora7.5

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kWlaboratorytestrig.Thedynamicsofa2MWsystemaresomewhatdifferentandareinvestigatedinthispaper.TheperformanceofthedynamiccontrollerforbothDFandIGmodeareshowninthissectionfora2MWwindturbine.

3.1.DFIGMode(TandQControl)

ThereferencevaluesforthecontrollerinDFmodearetorque(seefigure1)andstatorreactivepowertoenablethegridcoderequirement[11]tobeachieved,figure2.Twospeedsareinvestigatedinthissectiontoenablethe

performanceofthecontrollertobeshownbothaboveandbelowthe20%ofratedpowerlimitfromthegridcoderequirements.Anominalgeneratedpowerof320kWisachievedat1150rpm(lessthan20%ofratedpower)andanominalpowerof1.25MWisachievedat1550rpm(greaterthan20%oftheratedpower).Thereferenceandactualtorque,Te,andstatorreactivepower,Qs,areshownforbothspeeds

infigure5.

Thevalueofreferencetorque,Te*,forbothspeedsisthespecificnominaltorqueforagivenspeedcalculatedfromfigure1;2672Nmfor1150rpmand7701Nmfor1550rpm.Astepof200Nmisappliedatbothspeedstoillustratethedynamicresponsetoastepchangeintorque.Thevalueofreferencestatorreactivepower,Qs*,at1150rpmisvariedbetweenthelimitsspecifiedbythegridcoderequirements;initially5%ofthegeneratedpowerwithastepatt=3.5sto+5%ofthegeneratedpower.At1550rpmthestatorpowerfactor,pfs*,isinitially0.95leadingwithastepchangeatt=3stounitypfsandafinalstepatt=4stoa0.95laggingpfs.Thevectorcontrolloopsaretunedforatimeconstantof0.1sand0.9sfortheTeandtheQsloopsrespectively.Thevectorcontrolisdesignedtohaveaslowerbandwidththanthecurrentregulation.

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Theactualrotorcurrentdirect,irds,andquadrature,irqs,componentscorrespondingtofigure5areshowninfigure6.TheeffectofthestepchangeinTe*isapparentontheirqs(thesuperscriptsindicatesthatthevariableisreferredtothestator)ase*pected.Theirqs*componentat1550rpmcontainssmalltransientresponsesatt=3sandt=4sthatareduetothestepchangesintheQsvalue.ThestepchangeinQs*,showninfigure5,causesafastchangeinirds*,figure6,asthereisinitiallyanerrorbetweenthereferenceandactualQsasthecontroltakesashortwhiletorespond.Thecurrentregulationistunedtoensurethatthebandwidthpreventsthecontrollerrespondingtosuchtransientswhilestillachievingasuitablespeedofresponse.TheequationbasedtuningusedtodesignthecontrollergivessimilarvaluesofproportionalandintegralgainsforthecurrentregulationdirectandquadratureloopstothoseusedbyHoldsworthetal[10].

3.2.IGMode(TandFlu*Control)

ThereferencevaluesforthecontrollerinIGmodearestatorflu*linkageandtorque.Twoconditionsare

investigatedforthe2MWgeneratorinIGmode,start-upandtorquestepresponses,at400rpm(minimumIGmodespeed[12])and1420rpm(generatedpoweratthisspeedcorrespondstotheupperpowerratingofrotorconverter,600kW).Thereferenceandactualtorque,Te,andstatorflu*linkage,λsr(thesuperscriptrindicatesthatthevariableisreferredtotherotor),forbothspeedsareshowninfigure7.

Thesteady-stateTeisthenominalvalueforthespeedofoperation,320Nmfor400rpmand4081Nmfor1420rpmderivedfromfigure1.Astart-upsequenceisrequiredtoestablishtheratedλsrinthemachine,foragivenspeed,bymeansofaramp,figure7,beforethemachinecangeneratepower.

Oncethecontrollerreferenceλsrhasbeenestablishedinthemachine,theTe*isincreasedbymeansofacontrolledramptothenominalvalueforagivenspeedandthenastepresponseof50Nmstepat400rpmand200Nmat1420rpmisapplied.ThecontrollerregulatesthemachinetotrackTe*ase*pected,seefigure7.

Thevectorcontrolloopsdeterminethereferencerotorcurrentvaluesthatareshowninfigure8.Theirdcomponentinitiallyincreasesrapidlytoestablishtheλsrandisappro*imately3timesthenominalsteady-statevalueforagivenloadpoint.Thecurrentiswithintheratedlimitatalltimes.Theinitialirdcanbesignificantlyreducedifaslowerresponseofλsrisimplemented.

Theirqcomponentisregulatedbythetorquelooptoenablethedesiredpowertobegenerated.Initiallythereisaslighterrorduetothehighirdwhichaffectsthequadratureloopbythecrosscouplingterms.Oncenominalλsrisestablishedinthemachinethedirectandquadratureloopsaredecoupled.AgainaTestepcausesatransientspikeinirq*thoughthecontrolistunedtobeslowerthanthischangeinreferencevalue.

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4.CONTRIBUTIONOFROTORVOLTAGECOMPONENTS

TheperformanceofbothDFandIGmodehasbeenillustratedintheprevioussection.BothcontrollersarebasedonaninnercurrentloopandanoutercontrolloopfortorqueandstatorreactivepowerintheDFcaseandtorqueandstatorflu*linkageintheIGcase.DecouplingequationswerethenaddedtothePIcontrolleroutputstoreducetheeffectofcrosscouplingbetweentheloops.Thefinalpartofthisworkstudiesthecontributionofthesteadystatecomponentsofrotorvoltage,giveninfullineqns(1and2),fora2MWmachinetoassesstheimportanceofdecouplingequationsatvariousspeeds.Therotorvoltage,vrs,rotorcurrent,irs,andthenon-differentialcomponentsofvrsgivenbyeqns(1and2)areinvestigatedforthefullDFspeedrange(1000to1950rpm)withthenominaltorquedeterminedfromfigure1,andastatorpowerfactor,pfs,rangeof0.9laggingto0.9leading.OnlythepfsisconsideredastheGSIisassumedtomaintainunitypfattherotorconverterconnectiontothegridindependentoftheRSI.

Figure9showsthevariationofvrdqsforthespeedandstatorreactivepowerrangeinvestigated.Thevrdscomponentisdominatedinthesteady-statebytheωsfσirqstermasthevoltagedropacrossRrsisnegligibleandtheλsq

componentiszeroduetothechoiceofreferenceframe.Thiscanbeconfirmedbycomparingfigure9withfigures

11.Thevrqsina2MWmachineisdominatedbytheωsf(Lm/Ls)λsdtermasthelowtotalleakageinductance,σ,reducestheeffectoftheirdscrosscouplingtermandtheλsorientationframesetstheλsqcomponenttozero.Thevariationinvrqsatconstantspeed(andthereforetorque)isduetothecrosscouplingfromtheirdswhichisregulatingthestatorreactivepower,Qs,andthereforepfs.Thevrsmagnitudeisdominatedbythevrqscomponentandissymmetrical1500rpm;thesynchronousspeedfora4-polemachine.ThisisconfirmedbyParketal[13].Thesteady-statevariationinthedirect,irds,andquadrature,irqs,rotorcurrentcomponentswithrespecttospeedandQsisshowninfigure10.Theirdscomponentregulatesthestatorpowerfactor,pfs,bycontrollingQsandtheirdscomponentregulatesTe.Thevalueofirdsdeterminestheproportionofthegeneratorreactivepowersuppliedbythestatorandrotorcircuits.AnincreasinglypositiveirdsincreasestheproportionofQfromtherotorcircuitwhiledecreasingtheQfromthestatoruntilQise*portedbythestator.AnincreasinglynegativeirdsincreasestheQfromthestatorcircuit,reducingtheQfromtherotorsideuntilQise*portedbytherotor.QsincreaseswithTetomaintainthedesiredpfsandsotheirdscomponentwillbehigherforconstantpfsathigherspeeds.Theirqs

componentisappro*imatelyconstantatconstantspeedduetotheconstanttorqueandispositiveforgeneratedpowerduetotheorientationframeandthedirectandquadraturea*isalignment.Theirsmagnitudeiswithintheratedvalueforallconditionsconsideredinfigure10.

Theremainderofthissectionillustratestherotorvoltage,vrdqs,steady-statecomponentsfromeqns(1and2).TheRrsirdsterminvrdsandtheRrsirqsterminvrqsaresimplyirdqs,figure10,scaledbyRrsandsoarenotshown.

Thejσωsfirdqscrosscouplingtermsofvrdqsareshowninfigure11.Thejσωsfirqstermcontributestovrdsandσωsfirdsformspartofvrqs.Theσωsfirdscomponentvarieswithbothspeedandstatorreactivepowerasstatorreactivepowerisproportionaltotorqueforagivenstatorpowerfactor.Theσωsfirdscomponentincreaseswithspeedastheloadtorqueincreases,figure1.Theσωsfirqscomponentisthedominantterminthevrdscomponent,eqn(1),atnon-synchronousspeeds;thepolarityisaresultofωsfandthemagnitudeisdefinedbythetorque.Themagnitudeisirdqsscaledbyslipfrequency,ωsf,andthetotalleakageinductance,σ.Figure12showsthej(Lm/Ls)ωsfλsdq

毕业论文,开题报告。

componentofvrdqs.The(Lm/Ls)ωsfλsqtermcontributestovrds;thetermisappro*imatelyzeroduetotheorientationframe.The(Lm/Ls)ωsfλsdtermdominatesthevrqscomponent.Theshapeofthe(Lm/Ls)ωsfλsdcomponentisclearlyinfluencedbyωsf.

5.DISCUSSION

Thisanalysisenablesthevrdsandvrqscomponentstobecharacterisedbythedominantterms.TheλsorientationframeresultsintheλsqfeedforwardterminvrdsbeingnegligibleandsothesteadystatevrdscomponentisaresultofRrsirdsσωsfirqs.Threedistinctregionscanthenbeidentified,sub-synchronousspeed(lowirqsduetolowloadsovrdsisappro*imatelyRrsirds),aboutsynchronousspeed(ωsfisaround0sovrdsisappro*imatelyRrsirds)andsupersynchronousspeed(irdsandirqsarecomparableduetohigherloadtorqueandhighstatorpowerfactorsovrdsisappro*imatelyRrsirdsσωsfirqs).Thetransientresponseofvrdsforastepinirds*isdominatedbythepσirds.Thep(Lm/Ls)λsdtermhasanegligibleeffectastheλsdtermisconstantassumingastiffgrid.Anirds*stepaffectsboththesteadystatevalueofvrqsandthesteadystatetermsinvrds.

Thesteadystatevrqscomponentisdominatedbytheλsdterm,confirmedbyHopfenspergeretal[9](withthee*ceptionofsynchronousspeedwhenthesteadystatevrqsisdependentontheRrsirqsterm).Thetransientresponseofvrqstoanirqs*stepisdominatedbythepσirqstermasthedifferentialofthestepchangeinirqsisinitiallyhigh.Thep(Lm/Ls)λsqtermhasanegligibleeffectasλsqisappro*imatelyzero.Thevrdstermandthesteady-statetermsinvrqsalle*perienceachangeinvalueduetotheirqs*step.

6.CONCLUSIONS

ThispaperhasinvestigatedthecontrollerresponsefortheDFandIGmodeconnectionsfora2MWDFIGwindturbine.Themachineparametersforthe2MWmachinewereprovided,foracommerciallyavailableWRIMusedinwindturbines,bythemanufacturer.The2MWmachineparametersusedinthisworkarenotsimplyalinearscalingofpriorworkona7.5kWmachineandsothecharacteristicsarenotidenticalbetweenthetwomachines.Twoareasofanalysishavebeeninvestigatedwithrespecttothe2MWDFIG.E*istingsimulationmodelshavebeenusedtoevaluatethecontrollabilityandsteady-stateandtransientbehaviourofa2MWDFIGinDFandIGmode.TheoutcomeshowsthatIGmodeisacontrollablemodeofoperationwhichwille*tendthelowspeedoperationasrotorvoltagedecreases(asspeedreduces)andsothevoltagelimitoftheIGBTswillberespectedaswillthecurrentandpowerlimitsofthemachineandconverter.Thecompositionoftherotorvoltagewas

investigatedinDFmodeforthe2MWDFIG.ThisshowedhowtheimportanceofthedecouplingequationsontheperformanceoftheDFIGvariedwithspeed.

ACKNOWLEDGEMENTS

TheauthorsaregratefultoFKIIndustrialDrives