会员注册 | 登录 | 微信快捷登录 支付宝快捷登录 QQ登录 微博登录 | 帮助中心 人人文库renrendoc.com美如初恋!
站内搜索 百度文库

热门搜索: 直缝焊接机 矿井提升机 循环球式转向器图纸 机器人手爪发展史 管道机器人dwg 动平衡试验台设计

外文翻译风力发电中的自我激励与谐波.pdf外文翻译风力发电中的自我激励与谐波.pdf -- 5 元

宽屏显示 收藏 分享

资源预览需要最新版本的Flash Player支持。
您尚未安装或版本过低,建议您

rugged,egenerationcurrguidelines2PowerSystemNetworkDescriptionbinecanenterselfexcitationoperation.Thevoltageandfrequencyduringoffgridoperationaredeterminedbythebalancebetweenthesystemsreactiveandrealpower.Downloaded28Mar2008to211.82.100.20.RedistributionsubjecttoASMElicenseorcopyrightseehttp//www.asme.org/terms/Terms_Use.cfmWeinvestigateaverysimplepowersystemnetworkconsistingofone1.5MW,fixedspeedwindturbinewithaninductiongeneratorconnectedtoalinefeederviaatransformerH208492MVA,3phase,60Hz,690V/12kVH20850.Thelowspeedshaftoperatesat22.5rpm,andthegeneratorrotorspeedis1200rpmatitssynchronousspeed.AdiagramrepresentingthissystemisshowninFig.1.ThepowersystemcomponentsanalyzedincludethefollowingAninfinitebusandalonglineconnectingthewindturbinetothesubstationAtransformeratthepadmountOnepotentialproblemarisingfromselfexcitationisthesafetyaspect.Becausethegeneratorisstillgeneratingvoltage,itmaycompromisethesafetyofthepersonnelinspectingorrepairingthelineorgenerator.Anotherpotentialproblemisthatthegeneratorsoperatingvoltageandfrequencymayvary.Thus,ifsensitiveequipmentisconnectedtothegeneratorduringselfexcitation,thatequipmentmaybedamagedbyover/undervoltageandover/underfrequencyoperation.Inspiteofthedisadvantagesofoperatingtheinductiongeneratorinselfexcitation,somepeopleusethismodefordynamicbrakingtohelpcontroltherotorspeedduringanemergencysuchasagridlosscondition.WiththeproperchoiceofcapacitanceandresistorloadH20849todumptheenergyfromthewindturbineH20850,selfexcitationcanbeusedtomaintainthewindturbineatasafeoperatingspeedduringgridlossandmechanicalbrakemalfunctions.Theequationsgoverningthesystemcanbesimplifiedbylookingattheimpedanceoradmittanceoftheinductionmachine.ToContributedbytheSolarEnergyDivisionofTHEAMERICANSOCIETYOFMECHANICALENGINEERSforpublicationintheASMEJOURNALOFSOLARENERGYENGINEERING.ManuscriptreceivedFebruary28,2005revisedreceivedJuly22,2005.AssociateEditorDaleBerg.JournalofSolarEnergyEngineeringNOVEMBER2005,Vol.127/581Copyright©2005byASMEE.MuljadiC.P.ButterfieldNationalRenewableEnergyLaboratory,Golden,Colorado80401H.RomanowitzOakCreekEnergySystemsInc.,Mojave,California93501R.YingerSouthernCaliforniaEdison,Rosemead,California91770SelfExcitationWindPowerTraditionalwindturbinestheyareinexpensive,tiongeneratorsrequirisoftenused.Becausethecapacitorcompensationamongthewindturbine,tantaspectsofwindcontentintheoutputenaandgivessomeH20851DOI10.1115/1.20475901IntroductionManyoftodaysoperatingwindturbineshavefixedspeedinductiongeneratorsthatareveryreliable,rugged,andlowcost.Duringnormaloperation,aninductionmachinerequiresreactivepowerfromthegridatalltimes.Thus,thegeneralpracticeistocompensatereactivepowerlocallyatthewindturbineandatthepointofcommoncouplingwherethewindfarminterfaceswiththeoutsideworld.Themostcommonlyusedreactivepowercompensationiscapacitorcompensation.Itisstatic,lowcost,andreadilyavailableindifferentsizes.Differentsizesofcapacitorsaregenerallyneededfordifferentlevelsofgeneration.Abankofparallelcapacitorsisswitchedinandouttoadjustthelevelofcompensation.Withpropercompensation,thepowerfactorofthewindturbinecanbeimprovedsignificantly,thusimprovingoverallefficiencyandvoltageregulation.Ontheotherhand,insufficientreactivepowercompensationcanleadtovoltagecollapseandinstabilityofthepowersystem,especiallyinaweakgridenvironment.Althoughreactivepowercompensationcanbebeneficialtotheoveralloperationofwindturbines,weshouldbesurethecompensationisthepropersizeandprovidespropercontrol.Twoimportantaspectsofcapacitorcompensation,selfexcitationH208511,2H20852andharmonicsH208513,4H20852,arethesubjectsofthispaper.InSec.2,wedescribethepowersystemnetworkinSec.3,wediscusstheselfexcitationinafixedspeedwindturbineandinSec.4,wediscussharmonics.Finally,ourconclusionsarepresentedinSec.5.andHarmonicsinGenerationarecommonlyequippedwithinductiongeneratorsbecauseandrequireverylittlemaintenance.Unfortunately,inducreactivepowerfromthegridtooperatecapacitorcompensationthelevelofrequiredreactivepowervarieswiththeoutputpower,mustbeadjustedastheoutputpowervaries.Theinteractionsthepowernetwork,andthecapacitorcompensationareimporthatmayresultinselfexcitationandhigherharmonicent.Thispaperexaminesthefactorsthatcontrolthesephenomonhowtheycanbecontrolledoreliminated.H20852CapacitorsconnectedinthelowvoltagesideofthetransformerAninductiongeneratorFortheselfexcitation,wefocusontheturbineandthecapacitorcompensationonlyH20849therighthalfofFig.1H20850.Forharmonicanalysis,weconsidertheentirenetworkshowninFig.1.3SelfExcitation3.1TheNatureofSelfExcitationinanInductionGenerator.Selfexcitationisaresultoftheinteractionsamongtheinductiongenerator,capacitorcompensation,electricalload,andmagneticsaturation.Thissectioninvestigatestheselfexcitationprocessinanoffgridinductiongeneratorknowingthelimitsandtheboundariesofselfexcitationoperationwillhelpustoeitherutilizeortoavoidselfexcitation.Fixedcapacitorsarethemostcommonlyusedmethodofreactivepowercompensationinafixedspeedwindturbine.Aninductiongeneratoralonecannotgenerateitsownreactivepoweritrequiresreactivepowerfromthegridtooperatenormally,andthegriddictatesthevoltageandfrequencyoftheinductiongenerator.Althoughselfexcitationdoesnotoccurduringnormalgridconnectedoperation,itcanoccurduringoffgridoperation.Forexample,ifawindturbineoperatinginnormalmodebecomesdisconnectedfromthepowerlineduetoasuddenfaultordisturbanceinthelinefeeder,thecapacitorsconnectedtotheinductiongeneratorwillprovidereactivepowercompensation,andtheturDownloaded28Mar2008to211.82.100.20.RedistributionsubjecttoASMElicenseorcopyrightseehttp//www.asme.org/terms/Terms_Use.cfmoperateinanisolatedfashion,thetotaladmittanceoftheinductionmachineandtherestoftheconnectedloadmustbezero.Thevoltageofthesystemisdeterminedbythefluxandfrequencyofthesystem.Thus,itiseasiertostarttheanalysisfromanodeatoneendofthemagnetizingbranch.Notethatthetermimpedanceinthispaperistheconventionalimpedancedividedbythefrequency.Thetermadmittanceinthispapercorrespondstotheactualadmittancemultipliedbythefrequency.3.2SteadyStateRepresentation.Thesteadystateanalysisisimportanttounderstandtheconditionsrequiredtosustainortodiminishselfexcitation.Asexplainedabove,selfexcitationcanbeagoodthingorabadthing,dependingonhowweencounterthesituation.Figure2showsanequivalentcircuitofacapacitorcompensatedinductiongenerator.Asmentionedabove,selfexcitationoperationrequiresthatthebalanceofbothrealandreactivepowermustbemaintained.EquationH208491H20850givesthetotaladmittanceofthesystemshowninFig.2YSYMH11032YRH110320,H208491H20850whereYSH11005effectiveadmittancerepresentingthestatorwinding,thecapacitor,andtheloadseenbynodeMYMH11032H11005effectiveadmittancerepresentingthemagnetizingbranchasseenbynodeM,referredtothestatorsideYRH11032H11005effectiveadmittancerepresentingtherotorwindingasseenbynodeM,referredtothestatorsideH20849NotethesuperscriptH11032indicatesthatthevaluesarereferredtothestatorside.H20850EquationH208491H20850canbeexpandedintotheequationsforimaginaryandrealpartsasshowninEqs.H208492H20850andH208493H20850R1L/H9275H20849R1L/H9275H208502L1L2RRH11032/SH9275H20849RRH11032/SH9275H208502LLRH1103220H208492H20850whereFig.1ThephysicaldiagramofthesystemunderinvestigationFig.2Perphaseequivalentcircuitofaninductiongeneratorunderselfexcitationmode582/Vol.127,NOVEMBER20051LMH11032L1LH20849R1L/H9275H208502L1L2LLRH11032H20849RRH11032/SH9275H208502LLRH1103220H208493H20850R1LRSRLH20849H9275CRLH2085021L1LLLS−CRLH20849H9275CRLH2085021RSH11005statorwindingresistanceLLSH11005statorwindingleakageinductanceRRH11032H11005rotorwindingresistanceLLRH11032H11005rotorwindingleakageinductanceLMH11032H11005statorwindingresistanceSH11005operatingslipH9275H11005operatingfrequencyRLH11005loadresistanceconnectedtotheterminalsCH11005capacitorcompensationR1LandL1Laretheeffectiveresistanceandinductance,respectively,representingthestatorwindingandtheloadasseenbynodeM.Oneimportantaspectofselfexcitationisthemagnetizingcharacteristicoftheinductiongenerator.Figure3showstherelationshipbetweenthefluxlinkageandthemagnetizinginductanceforatypicalgeneratoranincreaseinthefluxlinkagebeyondacertainlevelreducestheeffectivemagnetizinginductanceLMH11032.Thisgraphcanbederivedfromtheexperimentallydeterminednoloadcharacteristicoftheinductiongenerator.Tosolvetheaboveequations,wecanfixthecapacitorH20849CH20850andtheresistiveloadH20849RLH20850valuesandthenfindtheoperatingpointsfordifferentfrequencies.FromEq.H208492H20850,wecanfindtheoperatingslipataparticularfrequency.Then,fromEq.H208493H20850,wecanfindthecorrespondingmagnetizinginductanceLMH11032,and,fromFig.3,theoperatingfluxlinkageatthisfrequency.Theprocessisrepeatedfordifferentfrequencies.Asabaseline,weconsideracapacitorwithacapacitanceof3.8mFH20849millifaradH20850connectedtothegeneratortoproduceapproximatelyratedVARH20849voltamperereactiveH20850compensationforfullloadgenerationH20849highwindH20850.AloadresistanceofRL1.0H9024isusedasthebaselineload.TheslipversusrotorspeedpresentedinFig.4showsthattheslipisroughlyconstantthroughoutthespeedrangeforaconstantloadresistance.Thecapacitancedoesnotaffecttheoperatingslipforaconstantloadresistance,butahigherresistanceH20849RLhighlowergeneratedpowerH20850correspondstoalowerslip.ThevoltageattheterminalsoftheinductiongeneratorH20849presentedinFig.5H20850showstheimpactofchangesinthecapacitanceFig.3AtypicalmagnetizationcharacteristicTransactionsoftheASMEDownloaded28Mar2008to211.82.100.20.RedistributionsubjecttoASMElicenseorcopyrightseehttp//www.asme.org/terms/Terms_Use.cfmandloadresistance.AsshowninFig.5,theloadresistancedoesnotaffecttheterminalvoltage,especiallyatthehigherrpmH20849higherfrequencyH20850,butthecapacitancehasasignificantimpactonthevoltageprofileatthegeneratorterminals.Alargercapacitanceyieldslessvoltagevariationwithrotorspeed,whileasmallercapacitanceyieldsmorevoltagevariationwithrotorspeed.AsshowninFig.6,foragivencapacitance,changingtheeffectivevalueoftheloadresistancecanmodulatethetorquespeedcharacteristic.TheseconceptsofselfexcitationcanbeexploitedtoprovidedynamicbrakingforawindturbineH20849asmentionedaboveH20850topreventtheturbinefromrunningawaywhenitlosesitsconnectiontothegridonesimplyneedstochoosethecorrectvaluesforcapacitanceH20849ahighvalueH20850andloadresistancetomatchtheturbinepoweroutput.Appropriateoperationoverarangeofwindspeedscanbeachievedbyincorporatingavariableresistanceandadjustingitdependingonwindspeed.3.3DynamicBehavior.Thissectionexaminesthetransientbehaviorinselfexcitationoperation.Wechooseavalueof3.8mFcapacitanceandaloadresistanceof1.0H9024forthissimulation.Theconstantdrivingtorqueissettobe4500Nm.Notethatthewindturbineaerodynamiccharacteristicandtheturbinecontrolsystemarenotincludedinthissimulationbecausewearemoreinterestedintheselfexcitationprocessitself.Thus,wefoFig.4VariationofslipforatypicalselfexcitedinductiongeneratorFig.5TerminalvoltageversusrotorspeedfordifferentRLandCJournalofSolarEnergyEngineeringcusontheelectricalsideoftheequations.Figure7showstimeseriesoftherotorspeedandtheelectricaloutputpower.Inthiscase,theinductiongeneratorstartsfromrest.Thespeedincreasesuntilitreachesitsratedspeed.Itisinitiallyconnectedtothegridandatt3.1secondsH20849sH20850,thegridisdisconnectedandtheinductiongeneratorentersselfexcitationmode.Att6.375s,thegeneratorisreconnectedtothegrid,terminatingtheselfexcitation.Therotorspeedincreasesslightlyduringselfexcitation,but,eventually,thegeneratortorquematchesthedrivingtorqueH208494500NmH20850,andtherotorspeedisstabilized.Whenthegeneratorisreconnectedtothegridwithoutsynchronization,thereisasuddenbrieftransientinthetorqueasthegeneratorresynchronizeswiththegrid.Oncethisoccurs,therotorspeedsettlesatthesamespeedasbeforethegriddisconnection.Figure8H20849aH20850plotsperphasestatorvoltage.Itshowsthatthestatorvoltageisoriginallythesameasthevoltageofthegridtowhichitisconnected.DuringtheselfexcitationmodeH208493.1sH11021tH110216.375sH20850,whentherotorspeedincreasesasshowninFig.7,thevoltageincreasesandthefrequencyisabithigherthan60Hz.Thevoltageandthefrequencythenreturntotheratedvalueswhentheinductiongeneratorisreconnectedtothegrid.Figure8H20849bH20850isanexpansionofFig.8H20849aH20850betweent3.0sandt3.5stobetterillustratethechangeinthevoltagethatoccursduringthattransient.4HarmonicAnalysis4.1SimplifiedPerPhaseHigherHarmonicsRepresentation.Inordertomodeltheharmonicbehaviorofthenetwork,wereplacethepowernetworkshowninFig.1withtheperphaseequivalentcircuitshowninFig.9H20849aH20850.Inthiscircuitrepresentation,ahigherharmonicormultipleof60HzisdenotedFig.6Thegeneratortorquevs.rotorspeedfordifferentRLandCFig.7Thegeneratoroutputpowerandrotorspeedvs.timeNOVEMBER2005,Vol.127/5834.1.2Transformer.WeconsiderathreephasetransformerwithleakagereactanceH20849XxfH20850of6percent.BecausethemagnetizDownloaded28Mar2008to211.82.100.20.RedistributionsubjecttoASMElicenseorcopyrightseehttp//www.asme.org/terms/Terms_Use.cfmbyh,wherehistheintegermultipleof60Hz.Thush5indicatesthefifthharmonicH20849300HzH20850.Forwindturbineapplications,theinductiongenerator,transformer,andcapacitorsarethreephaseandconnectedineitherWyeorDeltaconfiguration,sotheevenharmonicsandthethirdharmonicdonotexistH208515,6H20852.Thatis,onlyh5,7,11,13,17,...,etc.exist.4.1.1InfiniteBusandLineFeeder.TheinfinitebusandthelinefeederconnectingthewindturbinetothesubstationarerepresentedbyasimpleTheveninrepresentationofthelargerpowersystemnetwork.Thus,weconsiderasimpleRLlinerepresentation.Fig.8Theterminalvoltageversusthetime.„aVoltageduringselfexcitation.„bVoltagebeforeandduringselfexcitation,andafterreconnection.Fig.9Theperphaseequivalentcircuitofthesimplifiedmodelforharmonicanalysis584/Vol.127,NOVEMBER2005ingreactanceofalargetransformerisusuallyverylargecomparedtotheleakagereactanceH20849XMH11032H11015H11009→opencircuitH20850,onlytheleakagereactanceisconsidered.Assumingtheefficiencyofthetransformerisabout98percentatfullload,andthecopperlossisequaltothecorelossH20849ageneralassumptionforanefficient,largetransformerH20850,thecopperlossandcorelossareeachapproximately1percentor0.01perunit.Withthisassumption,wecancomputethecopperlossinperunitatfullloadcurrentH20849I1FullH6018Load1.0perunitH20850,andwecandeterminethetotalwindingresistanceoftheprimaryandsecondarywindingH20849aboutonepercentinperunitH20850.4.1.3CapacitorCompensation.Switchedcapacitorsrepresentthecompensationofthewindturbine.Thewindturbineweconsiderisequippedwithanadditional1.9MVARreactivepowercompensationH208491.5MVARabovethe400kVARsuppliedbythemanufacturerH20850.Thewindturbineiscompensatedatdifferentlevelsofcompensationdependingonthelevelofgeneration.ThecapacitorisrepresentedbythecapacitanceCinserieswiththeparasiticresistanceH20849RcH20850,representingthelossesinthecapacitor.Thisresistanceisusuallyverysmallforagoodqualitycapacitor.4.1.4InductionGenerator.TheinductiongeneratorH208491.5MW,480V,60HzH20850usedforthiswindturbinecanberepresentedastheperphaseequivalentcircuitshownFig.9H20849aH20850.TheslipofaninductiongeneratoratanyharmonicfrequencyhcanbemodeledasShhH9275s−H9275rhH9275sH208494H20850whereShH11005slipforhthharmonichH11005harmonicorderH9275sH11005synchronousspeedofthegeneratorH9275rH11005rotorspeedofthegeneratorThusforhigherharmonicsH20849fifthandhigherH20850theslipiscloseto1H20849Sh1H20850andforpracticalpurposesisassumedtobe1.4.2SteadyStateAnalysis.Figure9H20849bH20850showsthesimplifiedequivalentcircuitoftheinterconnectedsystemrepresentinghigherharmonics.Notethatthemagnetizinginductanceofthetransformersandtheinductiongeneratorareassumedtobemuchlargerthantheleakagesandarenotincludedforhighharmoniccalculations.Inthissection,wedescribethecharacteristicsoftheequivalentcircuitshowninFig.9,examinetheimpactofvaryingthecapacitorsizeontheharmonicadmittance,andusetheresultofcalculationstoexplainwhyharmoniccontentsofthelinecurrentchangeasthecapacitanceisvaried.Fromthesuperpositiontheorem,wecananalyzeacircuitwithonlyonesourceatatimewhiletheothersourcesareturnedoff.Forharmonicsanalysis,thefundamentalfrequencyvoltagesourcecanbeturnedoff.Inthiscase,thefundamentalfrequencyvoltagesourceH20849infinitebusH20850,Vs,isshortcircuited.Windfarmoperatorexperienceshowsusthatharmonicsoccurwhenthetransformeroperatesinthesaturationregion,thatis,athigherfluxlevelsasshowninFig.3.Duringtheoperationinthissaturationregion,theresultingcurrentcanbedistortedintoasharplypeakedsinusoidalcurrentduetothelargermagnetizingcurrentimbeddedintheprimarycurrent.Thisnonsinusoidalcurrentcanexcitethenetworkatresonantfrequenciesofthenetwork.FromthecircuitdiagramwecancomputetheimpedanceH20849atanycapacitanceandharmonicfrequencyH20850seenbytheharmonicsource,Vh,withEq.H208495H20850,wherethesignH20648representsthewordsinparallelwithTransactionsoftheASME
编号:201311171438576632    大小:755.90KB    格式:PDF    上传时间:2013-11-17
  【编辑】
5
关 键 词:
专业文献 学术论文 精品文档 外文翻译
温馨提示:
1: 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供交流平台,并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
  人人文库网所有资源均是用户自行上传分享,仅供网友学习交流,未经上传用户书面授权,请勿作他用。
0条评论

还可以输入200字符

暂无评论,赶快抢占沙发吧。

当前资源信息

4.0
 
(2人评价)
浏览:12次
淘宝运营上传于2013-11-17

官方联系方式

客服手机:13961746681   
2:不支持迅雷下载,请使用浏览器下载   
3:不支持QQ浏览器下载,请用其他浏览器   
4:下载后的文档和图纸-无水印   
5:文档经过压缩,下载后原文更清晰   

相关资源

相关资源

相关搜索

专业文献   学术论文   精品文档   外文翻译  
关于我们 - 网站声明 - 网站地图 - 友情链接 - 网站客服客服 - 联系我们
copyright@ 2015-2017 人人文库网网站版权所有
苏ICP备12009002号-5