高电压设备测试（High Voltage Equipment Testing）（英文版） 课件 Worksheet 3 Transformer Ratio and Grouping Measurement

《HighVoltageEquipmentTesting》TransformerRatioandGroupingMeasurement主讲人：何发武（副教授）OperatingWorksheet：OperatingWorksheet：TableofContents01Followme02Workshop03Training01FollowmeⅠ.IntroductionofTransformersThevoltageratioandconnectiongroupindicatedonthenameplateofatransformerareimportantparametersandessentialconditionsfortheparalleloperationofthetransformer.Iftheconnectedtransformerinparalleloperationhasinconsistentconnectiongroups,circulatingcurrentsmayoccurbetweenthetwotransformersafteroperation.Theconnectiongroupofwindingsshouldbemeasuredandcomparedwiththenameplatevalueduringtheproduction,manufacturing,factorytesting,handoveracceptance,andoverhauloftransformers.TherailwaytractiontransformeranditsnameplateareshowninFigures3-15,3-16.Ⅰ.IntroductionofTransformersFigure3-15

Exteriorofthree-phase220

kVrailwaytractiontransformerFigure3-16

Nameplateofthree-phase220/20

kVpowertransformerⅡ.TransformerVoltageRatioTestThevoltageratioisanimportantperformanceindicatorofatransformer.Thepurposeofmeasuringthevoltageratioofatransformerisasfollows:(1)Ensurethatthevoltageratioofeachtapofthewindingiswithintheallowabletechnicalrange.(2)Verifythecorrectnessofthewindingturnsandcheckiftheturnratiomatchesthenameplatetoensurethecorrectvoltagetransformation.(3)Determinewhethertheconnectionsoftheleadwiresandtapswitchesforeachtapofthewindingarecorrect.

Ⅱ.TransformerVoltageRatioTest(4)Identifywhetherthereareshortcircuitsbetweenlayersorturnsinthetransformerwinding.(5)Providebasisfordeterminingwhetherthetransformercanbeputintooperationoroperatedinparallel.Undertheconditionofno-loadoperationofthetransformer,theratioofthevoltageatthehigh-voltagewindingside(AX)tothevoltageatthelow-voltagewindingside(ax)(asshowninFigure3-17)iscalledthevoltageratioofthetransformer.

Ⅱ.TransformerVoltageRatioTestFigure3-17

Schematicdiagramofthevoltageratiobetweenthetransformer’sprimarywindingandthesecondarywindingⅡ.TransformerVoltageRatioTestQualifiedstandardsforturnsratioisshowninTable3-5.Table3-5

QualifiedstandardsforturnsratioⅢ.TransformerGroupsThetransformerconnectiongroupreferstothephasedifferencebetweenthelinepotentialofthesecondarywindingandthecorrespondinglinepotentialoftheprimarywinding.Itisrelatedtothewindingarrangement,thedirectionofthemarkedendsofthewindingwires,andtheconnectionmethodofthethree-phasewindings,asshowninFigure3-18.Figure3-18

TransformerconnectiongroupsⅢ.TransformerGroupsThephaseanglebetweenthelinevoltagesoftheprimaryandsecondarysidesofathree-phasetransformerdependsonthecoilconnectionmethod.Therearetwelvedifferentanglesatwhichthesecondarylinevoltagelagsbehindtheprimarylinevoltage,namely30,60,90,120,150,180,210,240,270,300,330,and360.Thesecorrespondtotwelvedifferentconnectionpoints,labeledas1,2,3,4,5,6,7,8,9,10,11and12,respectively.Ⅲ.TransformerGroupsCommonstandardgroupingsinclude:Yyn0forthethree-phasepowertransformerusedinthree-phasefour-wiredistributionsystemssupplyingmixedloadsforpowerandlighting;Yd11forthethree-phasepowertransformerusedinlowvoltagelinesabove0.4

kV;YNd11forthethree-phasepowertransformerusedinhighvoltagelinesabove110

kVwheretheneutralpointneedstobegrounded;YNy0forthethree-phasepowertransformerusedinsystemswheretheprimarysideneedstobegrounded;Yy0forthethree-phasepowertransformerusedinthree-phasepowerloadlines.Ⅲ.TransformerGroupsThecommonlyusedmainconnectiongroupsareshowninTable3-6.Table3-6

CharacteristicsandapplicationrangesofseveralcommonlyusedcoilconnectionsⅢ.TransformerGroupsThecommonlyusedmainconnectiongroupsareshowninTable3-6.Table3-6

CharacteristicsandapplicationrangesofseveralcommonlyusedcoilconnectionsⅢ.TransformerGroupsAccordingtothe“StandardforElectricalEquipmentHandoverAcceptanceTestinElectricalInstallationEngineering”(GB50150–2016):Whenthetapchangerleadsaredisassembledorthewindingisreplaced,theturnsratioandconnectiongroupofthetransformermustbetested.(1)Checkthevoltageratioofalltapjoints.Comparedwiththemanufacturer’snameplatedata,itshouldcomplywiththe“nosignificantdifference”ruleandfollowtherule.The“nosignificantdifference”ruleisasfollows:Forthetransformerwithavoltageoflessthan35

kVandavoltageratiooflessthan3,theallowabledeviationofthevoltageratiois±1%;forallothertransformers,theallowabledeviationoftheratedtapvoltageratiois±0.5%,andthevoltageratioofothertapsshouldbewithin1/10ofthetransformer’simpedancevoltagevalue,butnotmorethan±1%.Ⅲ.TransformerGroups(2)Checkthethree-phaseconnectiongroupofthetransformerandthepolarityoftheoutgoingwiresofthesingle-phasetransformer,whichmustmatchthedesignrequirementsandthemarkingsonthenameplateandsymbolsonthecasing.(3)Testprocedureforvoltageratiostatuscheckoftransformerwindingtapsinpowertransmissionandtransformationequipment.①Theinitialvaluedifferenceshouldnotexceed±0.5%(ratedtapposition)or±1.0%(otherposition)(warningvalue).②Thistestshouldbeconductedwhenthecorecomponentsorthemainbodyaredisassembledformaintenanceorwhenthereissuspicionofwindingdefects.Thetestresultshouldbeconsistentwiththenameplatemarkings.Ⅲ.TransformerGroupsThenameplateofadry-typepowertransformerisshowninFigure3-19.Figure3-19

Nameplateofdry-typepowertransformer02WorkshopⅠ.Transformerratiogrouptesting(Ⅰ)Transformerratiowiringdiagram(seeFigure3-20)Figure3-20

WiringdiagramoftransformerratiotestinginstrumentⅠ.Transformerratiogrouptesting(Ⅱ)Teststeps(1)Disconnecttheprimaryandsecondaryconnectionsofthetransformer.(2)Connectthehigh-voltageoutputsA,B,andCofthetransformerratiotestinstrumenttotheprimaryterminalsX,Y,andZofthetransformer,andconnectthelow-voltageoutputsa,b,andctothesecondaryterminalsx,y,zofthetransformer,asshowninFigure3-20.(3)Connectthegroundingterminalfirst,thenconnecttheinstrumentterminals,andgroundtheturnsratiotestinstrument.(4)Enterthe“transformergroup”“totaltapnumbers”“differential”and“ratedturnsratio”onthetransformerratiotestinstrument.Ⅰ.Transformerratiogrouptesting(5)Afterthetestiscompleted,recordthetestdata.(6)Afterfullydischargingthetransformer,disconnectthetestleadsofthetransformer.(7)Restoretheprimaryandsecondaryconnectionsofthetransformer.(8)Cleanupthesite.TheinstrumentisshowninFigure3-21.Figure2-21

FullyautomaticratiogroupingtesterⅡ.Testoperationmethod(1)Connection.Turnoffthepowerswitchoftheinstrument.Connectthehigh-voltageterminalsA,B,andCoftheinstrumenttothehigh-voltagesideofthetransformer,andconnectthelow-voltageterminalsa,b,andctothelow-voltageside.Thesingle-phaseandthree-phaseconnectionmethodsareshowninTable3-7.Table3-7

Single-phaseandthree-phaseconnectionmethodsⅡ.Testoperationmethod(2)Turnonthepowerswitchoftheinstrumentandenterthewiringmethodsettings.Basedontheactualnameplateinformationofthetransformer,selectYy,Y/d,Dd,andD/yforthesingle-phasetransformerorthree-phasetransformer,andselectDyforthethree-phasetransformerwhentheactualwiringmethodisunknown.Settheturnsratioaccordingtotheactualnameplateinformationofthetransformer.Forexample,fora10

kV/0.4

kVtransformer,enteraturnsratioof25andthenpressconfirmtosavethedataandexit.Pressthemeasurementbuttontostartthemeasurement.Afterthemeasurementiscompleted,themeasurementresultwillbedisplayedasshowninFigure3-22.Ⅱ.TestoperationmethodFigure3-22

TestresultsforthetransformerratiogroupⅡ.TestoperationmethodAsshowninthefigure3-22,theleftsiderepresentstheturnsratioforphasesAB(valuesof25.007,25.009,25.000),andtherightsiderepresentstherelativeerrorforphasesAB(valuesof0.03%,0.03%,0.00%).Ifthemeasuredrelativeerroroftheturnsratioisgreaterthan10%,itwillbedisplayedas“>10%”.Ifthemeasuredrelativeerroroftheturnsratioislessthan－10%,itwillbedisplayedas“<－10%”.Ⅲ.TestResultAnalysisBasedonthetestresults,comparethemwithrelevantstandards,factorydata,andtestdataofsimilarequipment.Accordingtothe“DL/T596–2021Pre-commissioningTestCodeforPowerEquipment”regulations.Ⅳ.PrecautionsInordertousethetestinginstrumentcorrectlyandobtainaccurateturnsratioerror,thefollowingissuesshouldbetakenintoaccountduringthetestingprocess.Whenconnectingthetransformertothetestinginstrument,makesurethatthehighandlow-voltagesidesarenotreversed.Ifthe“high/lowvoltagesidereversed”indicatoronthetestinginstrumentlightsupduringthetest,promptlyturnofftheinstrument,checkandcorrectthewiring,andthenconductthetest.Otherwise,highvoltagemayenterthebridge.Duringthetest,itisnotallowedtotouchtheterminalconnectionsofthetransformerandthetestinginstrument.Beforethetest,inputthetransformergroupbasedonthenameplatevalues,andtheinstrument