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首页 外文翻译 外文文献 英文文献 变压器励磁涌流的抑制

外文翻译 外文文献 英文文献 变压器励磁涌流的抑制.doc

外文翻译 外文文献 英文文献 变压器励磁涌流的抑制

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2017-09-18 0人阅读 举报 0 0 暂无简介

简介:本文档为《外文翻译 外文文献 英文文献 变压器励磁涌流的抑制doc》,可适用于战略管理领域

外文翻译外文文献英文文献变压器励磁涌流的抑制TransformerinrushcurrentsuppressionTransformerinrushcurrentleadsnotonlytotheprotectiverelayingmisoperation,derivedfromthepowergridvoltagesags,harmonicpollution,andtheinrushcurrent,ferromagneticresonanceovervoltageinpowersystemoperation,tobringthenegativeeffectthatcannotunderestimateFordecadesthepeoplethroughtheidentificationofinrushcurrentfeaturemethodtoreducetherelaymisoperationrate,butdidnotgainagoodreturn,malfunctionrateisstillhighAsforthevoltagesag,harmonicpollution,andtheinrushcurrent,eliminationofthemorebenonplussedoversthThereasonisthatpeoplethinktheinrushcurrentappearsirresistible,canonlyuse"recognition"countermeasure,namely"hide"countermeasureInfact,changeatrainofthought"inhibition",canbefullyrealized,andhaveachievedIntroductionTransformerinrushandsurgesuppressioncapacitorchargingprincipleiscompletelysimilartotheinductanceandcapacitanceareenergystoragedevices,theformerdoesnotallowcurrentmutation,whichdoesnotallowvoltagesurge,powerdropwillinduceatransientprocessAccessinthepowertransformernoloadtransformeroutletpowerfailureandprotectiondevicestoberemoved,becauseofasideofthetransformerwindingstofeelthesurgeappliedvoltagevaluesaresometimesgeneratedagreatinrushcurrentInrushcurrentpeakisnotonlylarge,andcontainsverymanyharmonicsandDCcomponentElectricalequipmentonthegridandthusresultinanextremelynegativeimpactthedangerofinrushcurrentcausedbythetransformerprotectiondevicesmalfunction,thefrequentfailureofthetransformerandputintooperationremovalofthetransformershortcircuitfaultoutletvoltagegeneratedwhenthesuddenincreaseintheprotectioninducedbytransformermalfunction,sothateachsideofthetransformerloadallthepowerApowerstationaccesstoapowertransformernoloadinrushcurrentgenerated,inducingotherBpowerstationnearby,Cpowerstationtransformersarerunninga"andshouldsurge"(sympatheticinrush)andfalsetripping,resultinginalargeareapowerfailurelargeinrushcurrentvalueofwouldresultinelectricpowertransformersandcircuitbreakersduetoexcessivedamageinducedovervoltage,damagedelectricalequipmentinrushcurrentoftheDCcomponentleadtoovercurrenttransformermagnetizationandmagneticsignificantlyreducethemeasurementaccuracyandthecorrectactionrateofprotectiondevicesmagnetizinginrushcurrentinalargenumberofharmonicsonpowerqualitycausedbypollutioncausedbyvoltagesagsorswells,affectingthenormaloperationofotherelectricalequipmentFordecades,peoplehavetakentotheinrushcurrentapproachisto"hide",butbecauseofinrushcurrentformandcharacteristicsofdiversity,throughmathematicalorphysicalmethodstoidentifyitscharacteristicsdifficulttoimprovetheaccuracyofthatinrushcurrentinthisfieldhasbeenahistoricalproblemthemagnetizinginrushcurrentcausesSuppressorisanimportantfeatureofthestrategyadoptedbymagnetizinginrushcurrentisnot"escape",but"suppression"Inrushcurrenttheoryandpracticethatcansuppressoreveneliminate,becausethesourceofinrushcurrentisgeneratedinthetransformerwindingsoneithersidefelttheappliedvoltageincreases,basedonfluxconservationtheorem,thewindingsinthemagneticcircuitwillproduceasinglepolarityofthemagneticbias,suchaspartialpoleandtransformerofexactlythesameastheoriginalremanencepolarity,itmaybiasmagneticremanenceandsteadystatefluxsuperimposedwiththeresultofmagneticsaturation,thusgreatlyreducingthemagnetizingreactanceofthetransformerwindings,andtheninducedasignificantinrushcurrentvalueAsthepartialmagneticpolarityandthevalueisappliedvoltageswitchbyselectingthephaseanglecontrol,andtherefore,ifwecangraspthepowertransformerwhenthelastofremanentmagneticpolarity,theycandropbywhenthecontroltransformerthesupplyvoltagephaseangle,whichallowsmagneticbiaswithoppositepolarityremanence,whicheliminatetheinrushcurrentofthesoilmagneticsaturation,toachievetheinrushcurrentForalongtime,peoplefounditimpossibletomeasurethetransformerpolarityandremanencevalues,andthushadtoabandontheuseoftheideaofpartialremanencemagneticoffsetInrushcurrentinresponsetothestrategydoesnotappearonthetwosmoothroad,aroadthroughthecontrolpowertransformervoltagedropclosingphaseangle,sothatitdoesnotproducemagneticbias,inordertoavoidmagneticsaturationoccurswhenthepowerdropsTheotherwayistheuseofphysicalormathematicalmethodforidentifyingthecharacteristicsofmagnetizinginrushcurrent,inordertolockinthepowertransformerprotectiondevicesdrop,thattheaforementioned"avoid"strategyThetwofatalroadhasitsproblems,capturedoesnotproducemagneticbiasvoltageclosingangleofonlytwo,namely,thetwosinusoidalvoltagepeakpoint(or),ifyoudeviatefromthesetwopoints,partialtherewillbemagnetic,whichrequirescontroloftheclosingpartofallinstitutions(includingcircuitbreakers)shouldbeaccurate,stableoperatingtime,because,asmillisecondtimedriftaction,closingphaseangleofwillproducetheerrorInaddition,threephasevoltageofthepeakisnotatthesametimecoming,butthedifferencebetween,tocompletelyeliminatethethreephaseinrushcurrent,mustbetimephasethreephasecircuitbreakerclosingcanbeachieved,andthecurrentoperatingrulesprohibitsuchpowerwillbeleadtotimesharingphasesplitphaseoperationrunning,nottomentionsomecircuitbreakersinthesubphasestructurecannotoperatedentificationwiththephysicalandmathematicalmethodsofmagnetizinginrushcurrentratherdifficult,becausethecharacteristicsofmagnetizinginrushcurrentandalotoffactors,suchasclosingphaseangle,theelectromagneticparametersofthetransformerandsoonAlargenumberofscholarsandengineersthroughdecadesofunremittingeffortsstillcannotfindaneffectiveway,becauseofitshighdegreeofdifficulty,thatisto"avoid"strategydifficult,theAchillesheelofthisstrategyistotoleratetheotherexcitationinrushcurrentoccurs,thepollutionofitspowergridandelectricalequipment,thereisstilldestructiveTransformerdiagramFigureisasinglephasetransformerstructure,wecanwritethenoloadvoltageoftheprimarywindingoftheequationWhereN,R,respectively,fortheprimarywindingturnsandtheresistance()()canberewrittenasWhereαt=,U,suchasignoringtheinitialphaseangleresistorR,whichLetR=,weobtainthesolution()typeequationshaveanexpressionforthemagneticfluxΦBasedonfluxconservationtheorem,intheclosingmomentsmagneticfluxcannotchangesuddenly,youcanfindtheintegrationconstantCTheamplitudeofthetotalfluxfromequation()isnotdifficulttoseethattheappliedvoltagetransformeruintheearlyphaseangleαdifferentwhenclosingthemagneticfluxgeneratedbyΦisnotthesame,theequation()isrewrittenas()forthetransientflux,thatis,magneticbias,intheclosingmomentsΦpvalueofαfortheordropatΦp=,atorwhendroppeduptothepeakΦmΦpEquation()inforthesteadystateflux,asaperiodicfunctionFigureforthedropclosingangleα=,thefluxcurve,thesteadystatefluxdiagramΦs,ΦisΦsandΦptotalfluxsynthetic(nottakingintoaccounttheremanenceΦres),ΦsatforthetransformersaturationfluxForthelosslesstransformer(R=)magneticbiasΦpwillnotdecay,thesolidlineshows,forlossytransformer(R>)Closingangleα=,thefluxcurveofFigureDashedlineAscanbeseenfromFigureinthevoltagephaseanglerangeθtoθgreaterthanthetotalfluxΦsaturationfluxΦsat,magneticsaturation,resultinginrushcurrentiy,iyhasadiscontinuityForthelosslesstransformerΦandiyisaboutevensymmetryofthewaveform,whilethediscontinuityintheiy=istheangularrangeofΦtheevensymmetricwaveformForΦandiyisdetrimentaltothetransformerwillnolongersymmetricalrelationshipWhentakingintoaccounttheremanence,theremanencewillbethetotalmagneticflux,magneticbias(transientflux)andsteadystatefluxofthethreecomponentsDifficulttoseeinFigureBiasinthecase,suchasremanenceupwardshift,thatmoresaturatedmagneticispositive,thetotalfluxcurvecircuit,inrushcurrentamplitudewillbegreaterIfremanenceisnegative,theinrushcurrentissuppressedCorematerialhysteresisloopinFigure、Figureisthehysteresisloopsofferromagneticmaterials,whichdescribestheexcitationcoilinthemagneticcircuitontheACvoltageapplied,thecorrespondingmagneticpotentialHHctoHcfrombetweenthechangeinmagneticfluxΦgeneratedbyH(ormagneticfluxdensityB=ΦS)inthecorrespondinghysteresisloopchangesIftheHlineatsomepointsuddenlybacktozero,thenBwillthenfallintotheBaxiscorrespondstoacertainpoint,thepointcorrespondingtotheBvalueistheremanenceBrRemanencevaluescanbeseenwiththeremovalofexcitationvoltageandpolarityofthephaseangle,andifinthefirst,excitationpoweroffquadrant(ie,H=)thentheremanenceispositiveorzero,in,quadrantcutofftheexcitationpower,theremanenceisnegativethemagnetizinginrushcurrentsuppressionmethodTransformerenergizedduringnormalworkinghours,themainmagneticfluxintheappliedvoltagewaveformandthewaveformisbasicallythesame,thatisasinewaveMagneticfluxlagsthesupplyvoltageof,bymonitoringthesupplyvoltagewaveformtoachievethefluxwaveformmonitoring,thengetoffwhenthesupplyvoltagepolarityremanenceDroponthepowertransformermagneticbiasΦpalsogeneratedasaresultofmagneticbias,thepowersupplyvoltagewhentheinitialphaseangleαin,quadrantbiasgeneratedwithintherangeofmagneticpolarityispositive,whiletheinitialphaseangleαin,quadrantbiasgeneratedwithintherangeofmagneticpolarityisnegativeClearly,theremanencepolarityshowsthatthemagneticpolaritybiascontrol,solongasthepowerdropandremanencemagneticpolarityoppositeside,heincurssurgesuppressionFigureforthetransformerprimaryvoltageu,themainmagneticfluxΦ,andthebiasmagneticremanenceΦResΦpwithsubgatetherelationshipbetweentheangleandclosinganglecurve,andthesubgatesupplyvoltageubeginningofthephaseangleα'withtheremanenceΦRescurveThemaintransformerinthesteadystatefluxΦlagthesupplyvoltageu,tTransformernoloadpowergeneratedwhenthemagneticbiasmustcorrespondwiththesteadystatevoltageuatpowerpointonthecurveofsteadystatefluxpowerequal,oppositepolarity,ThemaximumsteadystatefluxΦuptothepeakΦm,whiletheamplitudeofmagneticremanenceΦResmaterialcharacteristicsEasytoseetheearlyphasecorrespondstothesameangleαorclosingthesubgateinitialphaseangleα'andtheresultingmagneticremanenceoftheverypartialTransformerprimaryvoltageu,themainmagneticfluxΦ,andthebiasmagneticremanenceΦResΦpwithsubgatetherelationshipbetweentheangleandclosinganglecurveoftheopposite,thatismeasuredbythesubgatesubgatevoltageangleα',andα'preserved,theselectionofthetransformerinthenextdropintheclosingangleαequaltoα',whencoupledwithpower,andbiasmagneticremanencecanreverse,theywillbelessthanthesynthesisofmagneticfluxsaturationfluxΦsat(Duetosaturationfluxisgenerallylargerthanthesteadystatefluxpeakselection),themagneticcircuitisnotsaturated,inordertoachieveinrushcurrentsuppressionAsthethreephasethreephasesupplyvoltageofthecircuitbreakerwhenthelinkagehasbeencutthreephasesubphaseofthedifferencebetweenthegate,thephasedifferencebetweentheremanencepolarityis,andwhenclosingthethreephasethreephasecolinkageinitialphaseangledifferencebetweenthegateis,thephasedifferencebetweenthepartialpoleisalso,sothatthenaturalrealizationofthethreephasetransformermagneticcircuitbiasmagneticandremanenceareoffsettoavoidacircuitbreakermustbewithatimeshareinordertosuppressinrushcurrentdemanding,thatsupportforthreephasethreephasecircuitbreakerlinkagesurgesuppressionAslongasthepartialinhibitionofinrushcurrentandremanentmagneticpolarityoppositeto,arenotrequiredtofullyoffset,sowhentheclosinganglerelativetoagreaterangleoftheprevioussubgatebias,aslongasnomagneticbiasandremanenceareaddedtogether,themagneticcircuitnotsaturated,whichgreatlyreducestheoperatingtimeofcircuitbreakeroperatingmechanismprecisionrequirementsforthepracticalapplicationofthistechnologylaidthefoundationSuppressorandfastcuttingofsuchdevicesandequipmentcanberealizedfromtheinvestmentunitlinkedbycoldstandbysparetransformerrun,whichwillgreatlyreducenoloadtransformerhotstandbymodeenergyconsumptionFigurepresentsselectedfourinrushcurrentIyandthesubgateangleα'andtheclosingangleαofthecurve,youcansee,intheclosingangleαofor,dropthetransformerinrushcurrentandtransformerbeforesubsubgateanglehasnothingtodo,becausethetransformerprimaryvoltageoverpeakpowerdoesnotproducemagneticbias,regardlessofwhethertheoriginaltransformermagneticsaturationremanencewillnotOfcourse,ifyouusethreephasecircuitbreakerisnotpossiblelinkagephaseofthemagneticbiasiszeroAndwhentheclosingangleαisorwhenthedropthetransformerinrushcurrentandtheprevioussubgateangleα'iscloselyrelatedto,whenαandα'aresimilar(aboutadifferenceof)whentheinrushcurrentissuppressed,thenαandα'thegreaterthedeviation,thegreatertheinrushcurrentItcanbeseenasclosingthecircuitbreakerwhenthetimeshiftatmssurgesuppressionfornoinfluenceToday'svacuumcircuitbreakersandSFcircuitbreaker,closingtimedriftarewithinms,canaccuratelyachievetheinrushcurrentsuppressionTrippingangleα'andclosingangleαoftheinrushcurrentofFigureItshouldbenoted,afterastayinthethreephasepowertransformermagneticcircuitremanenceundernormalcircumstanceswillnotdecayaway,andnottochangepolarityOnlyinthetransformercorematerialabovetheCuriepointbythehightemperaturewilldecayordisappearaftertheremanence,butgenerallythepowerstationsitewillnothappenSaytheleast,remanencedisappearedagoodthing,aslongasthereisnoresidualmagnetism,magneticbiasalonewillnotcausemagneticsaturationConclusionDropchargingpowertransformerphaseanglephaseanglewiththepreviousremovalofthepowermatchingprinciple,intheoryandpracticehaveprovedthatthejointoperationintheuseofthreephasecircuitbreakercanbecompletelysuppressedwhentheinrushcurrentSimilarly,thepowercapacitorchargingphaseanglewiththelastdropcutpowerphaseanglematchingprinciple,canbeachievedwhenthecircuitbreakerclosinginhibittheinteractionofthreephasecapacitorchargingsurgeThetechnologyprotectionmalfunctioneradication,improvementofpowerquality,improveoperationalreliabilityareimportantThesamevarietyofvoltagelevelsofpowersystemreactivepowercompensation,longdistancetransmissionlineseriescompensationcontrolisalsoimportant变压器励磁涌流的抑制变压器励磁涌流不仅导致继电保护误动由其衍生的电网电压骤降、谐波污染、和应涌流、铁磁谐振过电压等都给电力系统运行带来不可低估的负面影响。数十年来人们通过识别励磁涌流特征的方法来减少继电保护的误动率但并未获得良好的回报误动率仍居高不下。至于对电压骤降、谐波污染、和应涌流等的消除更一筹莫展。究其原因是人们认为励磁涌流的出现不可抗拒只能采用“识别”的对策即“躲”的对策。其实换个思路“抑制”是完全可以实现的而且已经实现了。引言变压器励磁涌流与电容器的充电涌流抑制原理完全相似电感及电容都是储能元件前者不容许电流突变后者不容许电压突变空投电源时都将诱发一个暂态过程。在电力变压器空载接入电源时及变压器出线发生故障被继电保护装置切除时因变压器某侧绕组感受到外施电压的骤增而产生有时数值极大的励磁涌流。励磁涌流不仅峰值大且含有极多的谐波及直流分量。由此对电网及电器设备造成极为不利的影响。、励磁涌流的危害性引发变压器的继电保护装置误动使变压器的投运频频失败变压器出线短路故障切除时所产生的电压突增诱发变压器保护误动使变压器各侧负荷全部停电A电站一台变压器空载接入电源产生的励磁涌流诱发邻近其他B电站、C电站等正在运行的变压器产生“和应涌流”(sympatheticinrush)而误跳闸造成大面积停电数值很大的励磁涌流会导致变压器及断路器因电动力过大受损诱发操作过电压损坏电气设备励磁涌流中的直流分量导致电流互感器磁路被过度磁化而大幅降低测量精度和继电保护装置的正确动作率励磁涌流中的大量谐波对电网电能质量造成严重的污染。造成电网电压骤升或骤降影响其他电气设备正常工作。数十年来人们对励磁涌流采取的对策是“躲”但由于励磁涌流形态及特征的多样性通过数学或物理方法对其特征识别的准确性难以提高以致在这一领域里励磁涌流已成为历史性难题。、励磁涌流的成因抑制器的重要特点是对励磁涌流采取的策略不是“躲避”而是“抑制”。理论及实践证明励磁涌流是可以抑制乃至消灭的因产生励磁涌流的根源是在变压器任一侧绕组感受到外施电压骤增时基于磁链守恒定理该绕组在磁路中将产生单极性的偏磁如偏磁极性恰好和变压器原来的剩磁极性相同时就可能因偏磁与剩磁和稳态磁通叠加而导致磁路饱和从而大幅度降低变压器绕组的励磁电抗进而诱发数值可观的励磁涌流。由于偏磁的极性及数值是可以通过选择外施电压合闸相位角进行控制的因此如果能掌握变压器上次断电时磁路中的剩磁极性就完全可以通过控制变压器空投时的电源电压相位角实现让偏磁与剩磁极性相反从而消除产生励磁涌流的土壤磁路饱和实现对励磁涌流的抑制。长期以来人们认为无法测量变压器的剩磁极性及数值因而不得不放弃利用偏磁抵消剩磁的想法。从而在应对励磁涌流的策略上出现了两条并不畅通的道路一条路是通过控制变压器空投电源时的电压合闸相位角使其不产生偏磁从而避免空投电源时磁路出现饱和。另一条路是利用物理的或数学的方法针对励磁涌流的特征进行识别以期在变压器空投电源时闭锁继电保护装置即前述“躲避”的策略。这两条路都有其致命的问题捕捉不产生偏磁的电源电压合闸角只有两个即正弦电压的两个峰值点(或)如果偏离了这两点偏磁就会出现这就要求控制合闸环节的所有机构(包括断路器)要有精确、稳定的动作时间因为如动作时间漂移毫秒合闸相位角就将产生的误差。此外由于三相电压的峰值并不是同时到来而是相互相差为了完全消除三相励磁涌流必须断路器三相分时分相合闸才能实现而当前的电力操作规程禁止这种会导致非全相运行的分时分相操作何况有些断路器在结构上根本无法分相操作。用物理和数学方法识别励磁涌流的难度相当大因为励磁涌流的特征和很多因素有关例如合闸相位角、变压器的电磁参数等。大量学者和工程技术人员通过几十年的不懈努力仍不能找到有效的方法因其具有很高的难度也就是说“躲避”的策略困难重重这一策略的另一致命弱点是容忍励磁涌流出现它对电网的污染及电器设备的破坏性依旧存在。图为一单相变压器结构图可写出空载时初级绕组的电压方程式中N、R分别为初级绕组的匝数及电阻()可改写为式中α为t=时U的初相角如忽略电阻R即设R=则得求解()式微分方程得磁通Φ的表达式为依据磁链守恒定理合闸瞬间磁路中磁链不能突变即可求出积分常数C。式中可写出磁通Φ表达式式中为总磁通的幅值从式()中不难看出变压器外施电压u在不同初相角α合闸时所产生的磁通Φ都不相同将式()改写为式()中为暂态磁通即偏磁在合闸瞬间Φp的值与α有关在或空投时Φp=在或空投时Φp可达峰值Φm。式()中为稳态磁通为一周期函数。图为空投合闸角α=时的磁通变化曲线图中Φs为稳态磁通Φ为Φs和Φp合成的总磁通(未计及剩磁Φres)Φsat为变压器饱和磁通。对于无损变压器(R=)偏磁Φp不会衰减如实线所示对于有损变压器(R>)Φp按时间常数衰减如虚线所示。从图中可看出在电压相位角在θ至θ区间总磁通Φ大于饱和磁通Φsat磁路饱和因而产生励磁涌流iyiy具有间断性。对于无损变压器Φ和iy是关于的偶对称波形而在iy=的间断角区间Φ则是关于的偶对称波形。对于有损变压器则Φ与iy将不再有对称关系。当计及剩磁时总磁通将由剩磁、偏磁(暂态磁通)及稳态磁通三者组成。不难看出在图偏磁的情况下如剩磁为正则总磁通曲线向上平移即磁路更易饱和励磁涌流幅值会更大。如剩磁为负则励磁涌流将被抑制。图是铁磁材料的磁滞回线它描述在磁路的励磁线圈上施加交流电压时磁势H也相应的从Hc到Hc之间变化由H产生的磁通Φ(或磁通密度B=ΦS)将在磁滞回线上作相应的变化。如果H在回线上的某点突然减到零则B将随即落到对应B轴的某点上该点所对应的B值即为剩磁Br。可以看出剩磁的数值和极性与切除励磁电压的相位角有关如果在第、象限切断励磁电源(即H=)则剩磁为正或零在、象限切断励磁电源则剩磁为负。、励磁涌流的抑制方法变压器在正常带电工作时磁路中的主磁通波形与外施电源电压的波形基本相同即是正弦波。磁路中的磁通滞后电源电压通过监测电源电压波形实现对磁通波形的监测进而获取在电源电压断电时剩磁的极性。变压器空投上电时产生的偏磁Φp也一样因偏磁电源电压上电时的初相角α在、象限区间内产生的偏磁极性为正而初相角α在、象限区间内产生的偏磁极性为负。显然剩磁极性可知偏磁极性可控只要空投电源时使偏磁与剩磁极性相反涌流即被抑制。变压器初级电压u、主磁通Φ、剩磁ΦRes及偏磁Φp与分闸角和合闸角的关系曲线图,以及电源电压u分闸初相角α’与剩磁ΦRes的关系曲线。变压器处于稳态时主磁通Φ滞后电源电压u变压器空载上电时所产生的偏磁一定与稳态时对应上电时电压u曲线上电点的稳态磁通大小相等极性相反其最大值可达稳态磁通Φ的峰值Φm而剩磁ΦRes幅值与磁路材料的特性有关。不难看出对应同一个合闸初相角α或分闸初相角α’所产生的偏磁和剩磁的极性正好相反也就是说通过分闸时测量电源电压分闸角α’并将α’保存下来在下次空投变压器时选择在合闸角α等于α’时加上电源偏磁就可与剩磁反向它们的合成磁通将小于饱和磁通Φsat(曲线)(因饱和磁通一般选择大于稳态磁通峰值)磁路不会饱和从而实现对励磁涌流的抑制。由于三相电源电压在断路器三相联动切除时所得到的三相分闸相角各相差剩磁极性也是三相各相差而在三相联动合闸时三相的合闸初相角也是相差三相偏磁极性也各相差这样就自然实现了变压器三相磁路中的偏磁和剩磁都是抵消的从而避免了一定要断路器分相分时操作才能抑制励磁涌流的苛求也就是说三相联动断路器支持对三相涌流的抑制。由于抑制励磁涌流只要偏磁和剩磁极性相反即可并不要求完全抵消因而当合闸角相对前次分闸角有较大偏差时只要偏磁不与剩磁相加磁路就不会饱和这就大大降低了对断路器操作机构动作时间的精度要求为这一技术的实用化奠定了基础。将这种抑制器与快切装置和备自投装置联动即可实现备用变压器按冷备用方式运行这将大大节约变压器热备用方式的空载能耗。图选录了四条励磁涌流Iy与分闸角α’和合闸角α的关系曲线可以看到在合闸角α为或时空投变压器的励磁涌流与变压器的前次分闸角无关原因是在变压器初级电压过峰值时上电不产生偏磁不论变压器原来是否有剩磁都不会使磁路饱和。当然如果使用三相联动断路器是不可能做到三相的偏磁都为零。而当合闸角α为或时则空投变压器的励磁涌流与前次分闸角α’密切相关当α与α’相近(大约相差)时励磁涌流被抑制此后α与α’偏离越大励磁涌流也越大。由此可以看到如断路器的合闸时间漂移在ms时对涌流的抑制基本无影响。当今的真空断路器和SF断路器的分、合闸时间漂移都在ms之内完全可以精确实现对励磁涌流的抑制。’分闸角α与合闸角α对励磁涌流的影响曲线图应该指出变压器断电后留在三相磁路中的剩磁在正常情况下是不会衰减消失的不会改变极性。只有在变压器铁心受到高于材料居里点的高温作用后剩磁才会衰减或消失但一般的电站现场不会出现这种情况。退一步讲剩磁消失是件好事只要没有剩磁仅靠偏磁是不会引起磁路饱和的。、结束语电力变压器空投充电相位角与前次切除电源相位角匹配原则从理论及实践上都证明了在使用三相联动操作断路器时能彻底抑制励磁涌流。同样电力电容器空投充电相位角与前次切除电源相位角匹配原则也能实现抑制三相联动断路器合闸时的电容器充电涌流。这一技术对根除保护误动、改善电能质量、提高运行可靠性有重要意义。同样对各种电压等级电力系统的无功补偿、远距离输电线路的串联补偿控制等也有重要意义。

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