高电压设备测试（High Voltage Equipment Testing）（英文版） 课件 Worksheet 5 Transformer Oil Chromatographic Analysis

《HighVoltageEquipmentTesting》TransformerOilChromatographicAnalysis主讲人：何发武（副教授）OperatingWorksheet：OperatingWorksheet：TableofContents01Followme02Workshop03Training01FollowmeⅠ.GasChromatographicAnalysisofTransformerOil(Ⅰ)SignificanceofTransformerOilAnalysisGaschromatographicanalysisisprimarilyusedinthepowersystemtodetectdissolvedgasesinoil-immersedelectricalequipment.Undernormalcircumstances,theinsulatingoilandorganicinsulationmaterialsinoil-filledelectricalequipmentgraduallyageanddecomposeundertheinfluenceofheatandelectricity,resultinginthegenerationofvariouslow-molecular-weighthydrocarbons,carbondioxide,carbonmonoxide,andothergases.Mostofthesegasesaredissolvedintheoil.Ⅰ.GasChromatographicAnalysisofTransformerOilWhenthereislatentoverheatingordischargefaultintheequipment,thegenerationrateofthesegasesisaccelerated.Asthefaultdevelops,thedecomposedgasesformbubblesintheoil,whichcontinuouslydissolveintheoilthroughconvectionanddiffusion.Byregularlyanalyzingthegasesdissolvedintheoilusinggaschromatographicanalysisduringtheequipmentoperation,potentialinternalfaultsintheequipmentcanbedetectedearly,andthedevelopmentofthefaultcanbemonitored,allowingnecessarymeasurestobetakeninatimelymanner.Ⅰ.GasChromatographicAnalysisofTransformerOil(Ⅱ)GenerationofGasesinTransformerOilTheinsulationofoil-immersedelectricalequipment(suchastransformer,reactor,currenttransformer,oil-immersedbushing,andoil-immersedcable)mainlyconsistsofmineralinsulatingoilandorganicinsulationmaterialsimmersedintheoil(suchascablepaper,insulatingcardboard,etc.).Amongthem,mineralinsulatingoil,alsoknownastransformeroil,isadistillationproductofpetroleum.Itsmaincomponentsarealkanes(CnH2n+2),cycloalkanes(CnH2n),aromaticunsaturatedhydrocarbons(CnH2n－2),andothercompounds.Organicinsulationmaterialsaremainlycomposedofcellulose(C6H10O5).Ⅰ.GasChromatographicAnalysisofTransformerOilUndernormaloperatingconditions,boththeoilandsolidinsulationgraduallyageanddeteriorate,resultinginthedecompositionandgenerationofsmallamountsofgas(primarilyH2,CH4,C2H6,C2H4,C2H2,CO,andCO2,etc.).Whenthereisoverheating,dischargefaults,ormoistureintheinternaloftheelectricalequipment,theproductionofthesegasesincreasesrapidly.Mostofthesegasesdissolveintheinsulatingoil,whileasmallportionrisestothesurfaceoftheoil.Forexample,intransformers,somegasesescapefromtheoilandentergasrelays(gasdetectors).Thecompositionandcontentofvariousgasesintheoildirectlyrelatetothenatureandseverityoffaults.Therefore,byregularlymeasuringthecompositionandcontentofgasesdissolvedintheoilduringequipmentoperation,potentialinternalfaultsinoil-immersedelectricalequipmentcanbedetectedearly.Ⅰ.GasChromatographicAnalysisofTransformerOil(Ⅲ)CausesofcharacteristicgasesThevariousgascomponentsintheoilcanbeobtainedfromoilsamplestakenfromthetransformerandanalyzedbyagaschromatographafterdegassing.Basedonthecontent,characteristics,componentratios(suchasthethree-ratio),andgasgenerationrateofthesegases,theinternalfaultsofthetransformercanbedetermined.Inpracticalapplication,itisnotappropriatetosolelyrelyonthegascontentintheoilasthesolecriterionfordeterminingthepresenceorabsenceoffaultsintheequipment.Instead,acomprehensivejudgmentshouldbemadebasedonvariouspossiblefactors.ThegasesandtheircausesduringinternalfaultsinthetransformerareshowninTable3-9.Ⅰ.GasChromatographicAnalysisofTransformerOilTable3-9

GasandCauseduringInternalFaultsintheTransformerⅡ.GasChromatographicDiscriminationandAnalysisofPowerTransformerCurrently,inthefaultdiagnosisofthepowertransformer,itisoftendifficulttodetectcertainlocalizedfaultsandthermaldefectsthroughelectricaltestsalone.However,themethodofchemicaldetectionthroughgaschromatographicanalysisofgasesintransformeroilishighlysensitiveandeffectiveindetectingcertainlatentfaultsinsidethetransformerandassessingtheirdevelopmentatanearlystage.Whenthereisanoccurrenceofoverheatingfault,dischargefault,orinternalinsulationmoistureinthetransformer,thecontentofthesegasesgraduallyincreases.ThegascomponentscorrespondingtotheincreasedcontentduetothesefaultsareshowninTable3-10.Ⅱ.GasChromatographicDiscriminationandAnalysisofPowerTransformerTable3-10

ChangesinGasComponentsforDifferentInsulationFaultsⅡ.GasChromatographicDiscriminationandAnalysisofPowerTransformerWhenconductinganinternalfaultdiagnosisofthetransformerbasedonchromatographicanalysis,thefollowingaspectsshouldbeincluded:(1)Analyzethecausesandchangesofgasproduction.(2)Determinewhetherthereisafaultandthetypeoffault,suchasoverheating,arcdischarge,sparkdischarge,andpartialdischarge.(3)Assesstheconditionofthefault,suchashotspottemperature,severityofthefaultcircuit,anddevelopmenttrend.(4)Proposecorrespondingtreatmentmeasures,suchaswhethertocontinuetheoperation,technicalsafetymeasuresandmonitoringmethodsduringoperation,orwhethercoreliftinginspectionisrequired.Ifenhancedmonitoringisnecessary,thetestingcycleshouldbeshortened.Ⅲ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformer(Ⅰ)CriteriaforJudgingTransformerOilFaultsThe“Regulations”stipulatethecontentofdissolvedgasesinthetransformer.Ifanyofthevaluesexceedthespecifiedstandards,payattentiontoidentifyingthecauseofgasgeneration.Continuousmonitoringshouldbeconductedtoassessthepresenceoffaults,theseverityofthefaults,andtheirdevelopmenttrend.ThestandardfordissolvedgascontentinthetransformerisshowninTable3-11.Table3-11

SpecifiedValuesforGasContentinTransformerOilⅢ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformerAccordingtothe“Regulations”,whenthetotalgasgenerationrateofhydrocarbongasesisgreaterthan0.25

mL/h(opentype)and0.5

mL/h(sealedtype),ortherelativegasgenerationrateisgreaterthan10%/min,itcanbejudgedthatthereareabnormalitiesinsidethetransformer.ThemaingasesproducedbythedecompositionoffiberinsulationmaterialsintransformersathightemperaturesareCOandCO2,whilehydrocarbonsarepresentinsmallamounts.Whenoil-paperinsulationisexposedtoarcing,moreacetylenegaswillbegenerated.DuetothelargevariabilityinthemeasurementresultsofCOandCO2gases,therearecurrentlynocorrespondingstandardsspecified.Ⅲ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformerThe“Regulations”providecriteriafordeterminingthedeteriorationofgascontentintransformeroil.Thesecriteriacanbeusedtodeterminewhetherthetransformeroilhasdeteriorated,buttheycannotdeterminethenatureandconditionofthefaults.Ⅲ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformer(Ⅱ)QualitativeAnalysisofTransformerOilFaultTheuseofcharacteristicgasanalysiscanhelpdeterminethecausesoftransformerfaults.Thedissolvedgasesintheoilcanreflecttheelectricalandthermaldecompositionnatureofthesurroundingoilandpaperinsulationcausedbythefault.Thecharacteristicsofthegasesvarydependingonthetypeoffault,theenergyinvolved,andtheinsulationmaterialsaffected.Thereisacloserelationshipbetweentheunsaturationofhydrocarbongasesproducedatthefaultlocationandtheenergydensityofthefaultsource.Characteristicgasanalysiscanprovideavisualandconvenientwaytoroughlyanalyzeanddeterminethetypesoffaults.ThequalitativeanalysisofcharacteristicgascomponentsandfaultlocationsisshowninTable3-12.Ⅲ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformerTable3-12

QualitativeAnalysisofCharacteristicGasComponentandFaultLocationⅢ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformerWhentheH2contentincreaseswhileothergascomponentsremainunchanged,itmaybeduetowateringressorthechemicalreactionbetweenwaterandironcausedbybubbles,orthedecompositionorcoronaeffectofwaterorgasmoleculesunderhighelectricfieldstrength.Theacetylenecontentisakeyindicatorfordistinguishingbetweenoverheatinganddischargefaults.However,inmostoverheatingfaults,especiallywhentherearehigh-temperaturehotspots,asmallamountofacetylenecanalsobegenerated.Forexample,whenthetemperatureexceeds1,000C,asignificantamountofacetylenemayappear,whichcanbecausedbybothhigh-energydischargesandconductoroverheating.Acetylenecanalsooccurwhentapswitchesoverheat.Low-energypartialdischargesdonotgenerateacetyleneoronlyproduceaminimalamount.Ⅲ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformerUnderarcaction,gasesaregeneratedfromthedecompositionoftransformeroilandsolidinsulation,asshowninTable3-13.Table3-13

Gasesgeneratedfromdecompositionoftransformeroilandsolidinsulationunderarcaction(volume%)Ⅲ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformer(Ⅲ)Three-RatioMethodforTransformerFaultDiagnosisThethree-ratiomethodisusedtodeterminethenatureoftransformerfaultsbycomparingtheratiosofthreepairsofgasesamongfivegases.Differentcodesareusedtorepresentdifferentthreeratiovaluesanddifferentratioranges.Thecodingrulesforthethree-ratiomethodareshowninTable3-14,andthediagnosticcriteriaforfaultnatureusingthethree-ratiomethodareshowninTable3-15.Table3-14

Codingrulesforthethree-ratiomethodⅢ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformerTable3-15

Three-ratiomethodfordeterminingfaultnatureⅢ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformerWhentherearehigh-temperatureoverheatinganddischargefaultsinsidethetransformer,inmostcases,C2H2/C2H4

>3.Therefore,theremainingtwoitemsinthethree-ratiomethodcanbeusedtoformaCartesiancoordinatesystem,withCH4/H2astheordinateandC2H2/C2H6astheabscissa,formingaT(overheating)D(discharge)analysisjudgmentdiagramasshowninFigure3-38.Figure3-38

T-DanalysisjudgmentdiagramⅢ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformerTheTDdiagrammethodcandistinguishwhetherthetransformerisoverheatingordischargefault,anddividethelocaloverheating,coronadischarge,andarcdischargeareasaccordingtotheirratios.Thismethodcanquicklyandcorrectlyjudgethenatureofthefault,andplayamonitoringrole.Generally,internalfaultsofthetransformer,exceptfordischargefaultswithsuspendedpotentials,mostlystartwithoverheatinganddeveloptowardstheoverheatingareaⅡordischargeareaⅡ.Theyendupwithdirectdamagecausedbyoverheatingordischargefaults.ThedischargeareaⅡisamajorhiddendangerthatneedstobestrictlymonitoredanddealtwithearly.WhentheCH4/H2ratioapproaches3,itmaycauselightgasactionofthetransformerandsendasignal.Ⅲ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformerTheratiomethodbasedondissolvedgasanalysis(DGA)inoilcanbeusedtodeterminetransformerfaults.Thedissolvedgasesintheoil,includingH2,CH4,C2H6,C2H4,andC2H2,areusedascharacteristicdataforthetransformer’scondition.Themainfaultmodesofthepowertransformerduringoperationincludehigh-temperatureoverheating,medium-temperatureoverheating,partialdischarge,andarcdischarge.Forexample,whenthetransformerexperiencesahigh-temperatureoverheatingfault(temperature>700C),ethyleneisthemaincharacteristicgas,followedbymethane,andtheirsumusuallyaccountsformorethan80%ofthetotalhydrocarbons.Ⅲ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformerInthecaseofhigh-energydischarge,acetyleneandhydrogenarethemainfaultcharacteristicgases,followedbyethyleneandmethane.Acetylenegenerallyaccountsfor20%to70%ofthetotalhydrocarboncontent,andhydrogenaccountsfor30%to90%ofthetotalhydrogencontent.Generally,theethylenecontentishigherthanthemethanecontent.Ⅲ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformerBasedonthestatisticalanalysisofalargenumberofdetectedfaultytransformers,thetransformerconditionsareclassifiedintoninecategories:normaloperatingsequence,low-energydischargefaultsequence,high-energydischargefaultsequence,medium-temperatureoverheatingfaultsequence,high-temperatureoverheatingfaultsequence,screendendriticdischargesequence,interturnandinterlayerfaultsequence,tapswitchfaultsequence,andcoregroundingfaultsequence.Eachfaultsequenceisdescribedbyastandardfaultmode.ThestandardfaultmodesfortransformerfaultdiagnosisareshowninTable3-16.Ⅲ.TheRelationshipBetweenChangesinCharacteristicGasesandInternalFaultsoftheTransformerTable3-16

NinetransformerstandardfaultmodesⅣ.TransformerOnlineOilMonitoringSystemThetransformeronlineoilmonitoringsystemisapplicabletothetransformerandotherpowerequipment,asshowninFigure3-39.Themonitoringsystemshouldhavethecapabilitytodistinguishdifferenttypesofdischargesandissuealarmsfordangerouspartialdischargephenomena,ratherthandischargesignals.Figure3-39

Structureoftransformeroilcomprehensiveonlinemonitoringsystem02WorkshopⅠ.OilSampling(1)Thesamplingcontainershouldberinsedwithdistilledwaterordeionizedwater,followedbycleaningwithisopropylalcoholorhigh-purityethanolthathasbeentreatedforcleanliness,andthendriedforlateruse.(2)Thesamplingvalveforthetransformer’soperatingoilshouldbecleanedwithisopropylalcoholorhigh-purityethanolandallowedtoairdryorwipedcleanwithClassAgauze.Toavoidmixingresidualoilfromthevalvebodyintothesampleduringsampling,1–2Loftransformeroilshouldbeallowedtoflowoutnaturallyfromthevalvefirst,andthevalveopeningshouldbekeptconsistentduringflushingandsampling.(3)Thesamplingequipmentshouldbeplacedproperlytopreventcollisionbetweenglasswareduringtransportationandresultinginbreakage.Ⅱ.Start-upsteps(1)Checkifthereissufficientpressureinthenitrogen,air,andhydrogengascylinders.Ifthetotalpressureisbelow2

MPa,replacethecylinders.Checkthepressuregaugeonthelow-pressuresideofthepressure-reducingvalve,whichisgenerallyaround0.3

MPa.Checkforleaksinthegassystem,especiallyhydrogen.Ifanyleaksarefound,immediatelylocatetheleakingpointandtakecorrespondingmeasures.Confirmtheresolutionbeforeopeningthegascylinders.(2)Needlecleaning:Beforesampling,theglassneedleshouldbethoroughlycleanedwithtransformeroilfromtheequipment.Followtheprincipleofsmallamountsmultipletimes,witheachflushingusingnolessthan100

mLofoil.Thenumberofflushesshouldbenolessthan3times.Ⅱ.Start-upsteps(3)Duringsampling,ensureatightconnectionbetweentheneedleandtherubbertubetominimizecontactwiththeoutsideair.Thisensuresnoairbubblesintheoilsample.Attachalabelcorrespondingtotheequipmentnameoneachwell-takenoilsampleneedle.(4)Openthevalvesofthehydrogen,nitrogen,andaircylinders.Setthepressureofhydrogengasto0.2

MPa,andthepressureofnitrogenandairtoaround0.3

MPa.(5)Turnonthegaschromatographandensurethatthemeterontheleftsideofthegaschromatographdisplaysthecorrectreading.Setthetestconditionsandtemperaturecorrectly.Ifthegaschromatographhasnotbeenusedforalongtime(morethansixmonths),settheagingtemperature(forhowlongshouldbeaged),asshowninTable3-17,Table3-18andTable3-19.Ⅱ.Start-upstepsTable3-17

NormalreadingsonthemeterofthegaschromatographTable3-18

TestconditionsettingtemperatureTable3-19

AgingTemperatureⅡ.Start-upsteps(6)Afterconfirmingthereadingsonthemeterandsettingthetemperature,presstherunbutton,andtheheatinglampwillilluminate.Oncethesteadytemperaturelampisilluminated,presstheignitionbutton,andtwo“click”soundswillbeheard.Useasmallwrenchtoconfirmthattheflamehasbeenignited.Thenopenthebridgeflowtoensurethatthebridgeflowlampison.Next,turnonthecomputerandthenturnontheworkstation.Confirmthattheparametersofthegaschromatographarecorrect,asshowninTable3-20andTable3-21.Ⅱ.Start-upstepsTable3-20

DetectionparametersTable3-21

TimeparametersⅢ.SettingMethodforStandardSampleOpenthesoftwareanddouble-clickontheanalysismethod.Setthemethodfilename,devicenumber,selectshakingmethod,220

kVandbelow,anddevicestatus(runningstate).Setthestoptimeto8minutes.Choosetheprintingoptionsaccordingtoyourneeds,suchasprintingchromatographicanalysis,printinganalysisresultdata,andprintingjudgmentanalysisresults.Click“Finish”tocompletethemethodsetup.Selecttheanalysismethodandconfirmtheuseofthisanalysismethod.Clickon“CreateNewCalibrationCurve”.Double-clickonthecomponentnameandselectthecomponentname(intheorderofhydrogen,carbonmonoxide,carbondioxide,methane,ethylene,ethane,acetylene).Enterthestandardgasconcentrationforeachcomponentandconfirm.Ⅲ.SettingMethodforStandardSampleSelect“StandardSample”inthesampletype,andsetthestandardsamplenumberasConcentration1(switchingbetweenstandardsampleandtestsampletoachievethecorrespondingeffectdescribedabove).Afterthat,injectashotofthestandardsample.Oncethecurveappears,assignafilenametoitandconfirm.Clickon“CalibrationCurve”tocheckforcalibrationfactors(thereshouldbe).Theredcrossonthecalibrationcurveshouldchangetoacheckmark.Ⅳ.SetthealignmentAfterbuildingtheanalysismethod,injectashotofstandardgasandalignthespectrumafteritappears.Clickonthesystemoptionstoconfirmthatdualchannelsareselectedforsamplingandthatthemergedspectrumcalculationmodeisusedfordiagnosis.Clickonfilesettingsandselect“Automaticallymergespectraaftersamplingiscompleted”and“MergechannelBintochannelA”.Withthealignmentset,theiconinfrontofthecalibrationcurveshouldchangetoacheckmark.Now,injectthegassamplefordiagnosi