高电压设备测试（High Voltage Equipment Testing）（英文版） 课件 Worksheet 2 High Voltage Live Detection

《HighVoltageEquipmentTesting》HighVoltageLiveDetection主讲人：何发武（副教授）OperatingWorksheet：TableofContents01Followme02Workshop03Training01FollowmeⅠ.OverviewofLiveDetectionStatemonitoringiswidelyusedinthepowersystem,andelectricalequipmenttestingismainlydividedintoonlinemonitoringandlivedetection.Onlinemonitoringreferstothecontinuousanduninterruptedautomaticdetectionoftheelectricalstateoftheliveoperationofelectricalequipmentthroughtestinginstrumentswhiletheequipmentisinoperation.Itcandetectpotentialequipmentfailures,especiallyinthestatusdetectionofintelligentsubstations,whereitplaysanextremelyimportantrole.Livedetectionreferstothemonitoringofequipmentstatuson-sitewithoutapoweroutage.Itisoneoftheeffectivemeasuresforreal-timeanduninterruptedmonitoringanddiscoveringequipmentdefects.High-voltagelivedetectionrealizestheall-aroundmonitoringofhigh-voltageequipmentthroughsensorsanddatatransmissiontechnologies.Ⅰ.OverviewofLiveDetectionThedifferencebetweenlivedetectionandpoweroutagedetectionliesinwhetherpoweroutagedetectionisusedtoconfirmtheelectricalperformanceoftheequipment.poweroutagedetectionisalsocalledpreventivetestingofpowerequipment.Theobjectsoflivedetectioninclude:transmissionline,transformer,circuitbreaker,disconnectswitch,instrumenttransformer,bushing,lightningarrester,powercapacitor,GIS,reactor,powercable,andothermajorprimaryequipment,asshowninFigure4-13.Itcandetecttheproblemsofprimaryelectricalequipmentintheoperationstate,includingpartialdischarge,overheatingfaults,gasleakagefaults,etc.,toavoidmajoraccidents.Ⅰ.OverviewofLiveDetectionThesignificanceoflivedetectionistodetectthehiddendefectsthatmayexistinequipmentduringlong-termoperationwhiletheequipmentisrunning,whichcanbetimelyidentified,treatedaccordingtothelevelandtypeoffaults,andflexiblyarrangemaintenancecycles,reducepoweroutages,andimproveequipmentreliability.Figure4-13

CapacitorandreactorwithcompensationfunctionintractionnetworkⅡ.ThebasicmethodoflivedetectionThecurrentlivedetectiontechnologymainlyincludesthetransformer,GISandSF6circuitbreakerpartialdischargetest,transformeroilchromatography,capacitiveequipmentcapacityanddielectriclosschargedtest,zincoxidearresterleakagecurrent,ultrasonicdetection,ultravioletacousticimaging,infraredimagingdetectionmethodandsoon.Ⅱ.Thebasicmethodoflivedetection1.UltrasonicMethodWhentherearegaps,cracks,delaminations,interlayers,andotherdefectsinthemetalofelectricalequipmentsuchastransformers,high-voltageswitchgear,GIS,etc.,ultrasonicwavespropagatetotheinterfacebetweenthemetalandthedefect,resultinginpartialorcompletereflection.Theseultrasonicwavescannotbeheardbyhumans.Ultrasonictestingisamethodthatutilizesinstrumentstoreceiveultrasonicsignalsthatundergorefractionandreflectionattheinterfaceofinsulatingmaterials.Afterconversionandprocessingbyelectroniccircuits,itcandetectdefectssuchascracksandfracturesintheinsulatingmaterials.Thismethodhasthefunctionofrelativelylocatingfaults,andthechangesinwaveformcharacteristicscorrespondtothedepth,position,andsizeofthedefects.Ⅱ.ThebasicmethodoflivedetectionTheultrasonicmethodcandetectinternalfaultsinequipmentbyemittingandreceivingultrasonicsignals.Itcanalsodetectequipmentfaultsbyonlyreceivingultrasonicandelectromagneticwaveinformationemittedduringlocalizeddischargefaultsinsidetheequipment.Thefrequencyofultrasonicwavesisintherangeof20to100kHz.TheresultsaredisplayedindB(mV)values,curves,orimages,providingfunctionssuchasfaultidentificationandlocalization.Acoustic-opticmeasurementcombinesacousticmeasurementandfiberopticmeasurement.Whenpartialdischargeoccursinsideatransformer,itgeneratesultrasonicwavesthatexertpressureontheinstalledopticalfibersinsidethetransformer,causingdeformation.Thisleadstochangesinthelengthoftheopticalfibersandtheirrefractiveindex.Bydemodulatingthemodulatedwaveform,thesourceanddischargelocationoftheultrasonicwavescanbedetectedusingademodulator,providingaccuratetechnicalsupportformaintenance.Ⅱ.Thebasicmethodoflivedetection2.InfraredandultravioletimagingmethodThermalfaultsinpowerequipmentcanbedividedintoexternalthermalfaultsandinternalthermalfaults.Externalthermalfaultsincludeheatingcausedbyresistancechangesatwireconnections,connectors,etc.Internalthermalfaultsincludeunevendistributionofthermalelectricfieldscausedbyheatingatcontactconnectionpointsofsolid,liquid,andgasdielectricsinsidetheequipment.Ⅱ.ThebasicmethodoflivedetectionInfraredimagingisanon-contactdetectiontechniquethatallowsthevisualizationofdefectsthatarenotvisibletothenakedeye.Itcanprovideclearvisualimagesofthesedefects,enablingreal-timeandonlinemonitoringanddiagnosisofmostelectricalequipmentfaults.Inhigh-voltagemeasurementscenarios,infraredimagingisparticularlysensitivetodefectssuchasresistancelosses,corelosses,dielectriclosses,temperaturedifferencescausedbyunevenvoltagedistribution,andtemperaturedifferencescausedbyoil-immersedequipmentwithoildeficiency.Ⅱ.ThebasicmethodoflivedetectionTheprincipleoftheinfraredimagingmethodisthatthetemperaturefieldofdifferentpartsofhighvoltageelectricalequipmentinoperationcanbejudgedaccuratelybyusingtheinfraredthermalimagingmethodanddifferentcolorstodistinguishanddisplaywhetherthereistoohighlocaltemperatureonthesurfaceandinsideofpowerequipment.Todeterminewhethertheequipmenthasinsulationdefectssuchasdielectriclossorresistanceloss,itisparticularlysensitivetoearlyfaultdefectsandtheinsulationstatusofelectricalequipment.Thedisadvantageisthatduetothesmallinfraredpenetrationability,therearesomelimitations,mostofthenon-conductivematerialpenetrationthicknessislessthan1

mm.Therefore,infraredrayscanonlydetectthecharacteristicthermalelectricfielddistributionformedonthesurfaceoftheequipment,andcannotdetecttheinternaloperationstatefromtheoutsideoftheequipment.Ⅱ.ThebasicmethodoflivedetectionThecommonfaultsofhighvoltageequipmentdetectedbyinfraredimagingmethodareasshowninTable4-4.Table4-4

CommonFaultsDetectedbyInfraredImaginginHigh-VoltageEquipmentⅡ.ThebasicmethodoflivedetectionUltravioletimagingmethodismainlybasedonthetheoryofcoronadischarge.Whenhigh-voltageequipmentexperiencescoronadischarge,itemitsultravioletradiation.Afterbeingreceivedandprocessedbyanultravioletcamera,theimageoverlapswithvisiblelightimagesandisdisplayedonthescreen.Thisallowsfordirectobservationofsurfacedischargeofhigh-voltageequipment,determiningthelocation,shape,andintensityofcoronadischarge.Therefore,itcandetectinsulationdefectssuchasequipmentdamage,dirt,partialdischargecausedbycarbonization,erosiondamage,andinsulationdegradation,accuratelydeterminingthehealthconditionoftheequipment.Ⅱ.ThebasicmethodoflivedetectionThewavelengthofinfraredisintherangeof8–14m,whilethewavelengthrangeofultravioletisintherangeof40–400

nm.Thedifferencebetweenultravioletandinfraredistheirwavelength.Duetotheabilitytooperateindaylight(“day-blindband”),ultravioletimagingremainsstableandclearevenunderbrightsunlight.Itissuitablefordetectingthelocationandintensityofcoronadischarge,arcs,andsurfacepartialdischargecausedbycracks,dirt,surfacedamage,andloosenessinpowerequipment.Itisparticularlyeffectiveindetectingcoronadischargelocationsininsulators,wireconnections,equipotentialrings,andotherpowerequipmentinoverheadlinesandhigh-voltagesubstations.Duringmeasurement,attentionshouldbepaidtotheinfluenceoftemperature,humidity,airpressure,windspeed,fieldofviewangle,detectiondistance,instrumentgain,andotherfactorsontheaccuracyofcoronadischargedetectiontoreducemeasurementerrors.Ⅱ.Thebasicmethodoflivedetection3.LeakagecurrentoflightningarresterCurrently,non-gappedzincoxidelightningarresters(MetalOxideArrester,MOA)aremainlyusedinsubstations,anddampnessandagingarethemaincausesoflightningarresterfailures.Undernormaloperatingvoltage,thecurrentpassingthroughthelightningarresterisverysmall,rangingfromtenstohundredsofmicroamps(A),whichiscalledACleakagecurrentunderoperatingvoltage,alsoknownastotalcurrent.Undernormalcircumstances,thecapacitivecomponentaccountsforthemajorityofthetotalcurrent,whiletheresistivecomponentaccountsforabout10%to20%ofthetotalcurrent.Whenthelightningarresteragesorgetsdamp,itsresistivecurrentgraduallyincreases,andtheproportionofresistivecurrentinthetotalcurrentalsoincreasesaccordingly,leadingtoanincreaseinthetotalcurrent.Therefore,thischaracteristiccanbeusedtojudgetheoperatingstateofmetaloxide.Ⅱ.ThebasicmethodoflivedetectionTheincreaseinresistivecurrentreflectsthedefectsofthelightningarresterwhenitisseverelydamp,aged,orhasseriousinsulationdegradation.Bymonitoringthetotalcurrentorresistivecurrentofthelightningarresterduringoperationandcomparingtheobtaineddatawiththefactoryandhistoricaldata,insulationdefectsofthelightningarrestercanbediscovered.Inthefield,thethirdharmoniccurrentmethodisusedtoobtainthetotalcurrentfromthelightningarrestergroundingline,andthethirdharmonicisobtainedthroughathirdharmonicbandpassfilter.Bydetectingthechangesinharmoniccurrent,theagingstateofthemetaloxidelightningarrestercanbedetermined.Ⅱ.ThebasicmethodoflivedetectionTheinitialcurrentvalueofMOAreferstothecurrentvaluepassingthroughitmeasuredduringcommissioning.BymonitoringtheACleakagecurrentandresistivecomponentofthezincoxidelightningarresterunderoperatingvoltage,insulationdefectssuchasagingordampnesscanbedetermined.Thechangeinresistivecurrentflowingthroughthezincoxidelightningarresterunderratedoperatingvoltagedirectlyreflectsthequalityofitsinsulationperformance,withanincreaseinresistiveleakagecurrentbeingusedasajudgmentcriterion.Whenthefundamentalcomponentoftheresistivecurrentincreasessignificantlyandthecontentofharmonicsdoesnotincreasesignificantly,itgenerallyindicatesseverepollutionordampness.Whenthecontentofharmonicsintheresistivecurrentincreasessignificantlyandthefundamentalcomponentdoesnotincreasesignificantly,itgenerallyindicatesaging.Ⅱ.ThebasicmethodoflivedetectionThemainmethodsofMOAonlinemonitoringareshowninTable4-5.Table4-5

MainmethodsforonlinemonitoringofMOAⅡ.ThebasicmethodoflivedetectionMeasurementsaretakenunderoperatingvoltagetoassessthefullcurrentandresistivecurrent,reflectingtheconditionoftheMOA.Changesinthefullcurrentcanindicateseveremoistureingress,poorinternalcomponentcontacts,andsignificantvalveaging.However,changesinresistivecurrentaremoresensitivetoearly-stagevalveaging.Forexample,whenthepeakresistivecurrentincreasesfrom50Ato250A,theincreaseinoverallcurrentmayonlybeafewpercentagepoints.Ⅱ.ThebasicmethodoflivedetectionTomeasurethefullcurrent,acontinuousonlinemonitoringdeviceisconnectedinseriesbetweenthebottomofthelightningarresterandthegroundtomonitorthefullcurrent.Whenmeasuringtheresistivecurrent,thestabilityofthevalveplateofthelightningarrestermainlyreliesonmonitoringtheresistivecurrent.Theresistivecurrentismoresensitivetoearly-stagevalveagingandmoistureingress.Sincethecurrentvaluesofthearresterunderoperatingvoltagearesmall(intheArange),strictrequirementsareplacedonthesensor.Whenselectingaleakagecurrentsensorforthearrester,highsensitivityandgoodstabilitysensorsarechosen,takingintoaccounttheeffectsofinterphaseinterferencewhilemonitoringtheresistivecurrent.Duringmeasurements,attentionshouldbegiventoweatherconditions,voltagefluctuations,wiringmethods,electromagneticinterference,andstraycurrents,amongotherfactorsthatmayaffecttheaccuracyofthemeasurements.Ⅱ.ThebasicmethodoflivedetectionTheinfluenceofhumiditycancauseanincreaseintheexternalinsulationleakagecurrentofthearrester,leadingtosignificantchangesintheonlinemeasurementvalues.Humidityisalsoessentialdatawhenconductinglongitudinalcomparisonsofarresters.Duringonlinemonitoringoftemperatureandhumidity,anexternaltemperatureandhumiditymeterinstalledon-siteisusedtocollecttemperatureandhumidityinformation,whichisthentransmittedtotheonlinemonitoringsystemthroughdataconversiondevices.Thechargedtesterforzincoxidearresters(seeTable4-4)canbeusedinplaceswherethearresterisenergized,de-energized,orinalaboratory,enablingsimultaneousmeasurementofthree-phasecurrentandvoltage.WiringdiagramforACleakagecurrenttestunderoperatingvoltageisshowninFigure4-15.DataanalysisofzincoxidearresterresistivecurrentlivedetectionisshowninTable4-6.Ⅱ.ThebasicmethodoflivedetectionFigure4-14

ZincoxidearresterlivetesterFigure4-15

WiringdiagramforACleakagecurrenttestunderoperatingvoltageⅡ.ThebasicmethodoflivedetectionThereshouldbenosignificantchangesinthefullcurrent,resistivecurrent,andinitialvalues.Iftheresistivecurrentdoubles,thepowershouldbeturnedoffforinspection.Iftheresistivecurrentincreasesto1.5timesitsinitialvalue,monitoringshouldbestrengthened.Table4-6

DataanalysisofzincoxidearresterresistivecurrentlivedetectionⅡ.ThebasicmethodoflivedetectionIfthepercentageofresistivecurrenttofullcurrentincreasessignificantly,withalargeincreaseinthefundamentalwaveandnosignificantincreaseinharmonicwaves,itcanbedeterminedthatthelightningarresterisseverelycontaminatedorhasinternalmoistureingress.Ifthepercentageofresistivecurrenttofullcurrentincreasessignificantly,withalargerincreaseinharmonicwavesandnosignificantincreaseinthefundamentalwave,itcanbedeterminedthatthearresterisaging.Ⅱ.Thebasicmethodoflivedetection4.LiveDetectionofCapacitiveequipmentcapacitanceandDielectricLossCapacitancemonitoringofcapacitanceequipmentisapplicabletocablesystems,tapgroundingend,currenttransformers,capacitivevoltagetransformers,capacitivebushings,capacitivecouplers,andothercapacitance-typedevices.Itutilizesacomparativemethodtomeasurethedielectricratioinordertodetectinternalconditionssuchasmoistureingressintheequipment.Ⅱ.ThebasicmethodoflivedetectionInthefield,a0.1

Hzultra-lowfrequencydielectriclosstestiscommonlyusedtodetermineifelectricalequipmentisaffectedbymoistureoraging.Duringthetest,a0.1

Hzpowersupplyisappliedtoapply0.5,1.0and1.5timestheratedphasevoltageU0tothepowerequipment.Multiplemeasurementsofthedielectriclossaretakenateachvoltageleveltoobtaintheaveragevalueandstandarddeviationforassessingthehealthoftheelectricalequipment.Ⅱ.Thebasicmethodoflivedetection5.LivedetectionofoilchromatographicTheprincipleofoilchromatographiclivedetectionsystemisthroughthelivedetectionofgasH2,CO,CH4,C2H6,C2H4,andC2H2dissolvedintransformerinsulatingoil,thetypeandconcentrationoftransformeroilgasaredetectedtodeterminewhetherthereisafaultorlatentprobleminthetransformer,asshowninTable4-7.Thelivedetectionprocessofoilchromatographyisthatthetransformeroilenterstheoilandgasseparationchamberforoilandgasseparation.Theseparatedgasflowsthroughthechromatographiccolumntoseparatethefaultgasinturn.Ⅱ.ThebasicmethodoflivedetectionTable4-7

TransformerFaultsandIncreasedGasComponentsTableⅡ.ThebasicmethodoflivedetectionThegassensormonitorsthegasandconvertsthefaultgasandgasconcentrationintoelectricalsignals.Theelectricalsignalisprocessed,andthetypeandconcentrationofeachfaultgasarecalculated.Thedataisrecordedandsaved,andthecriticalvalueofthefaultgasconcentrationissetinthesystem.Whenthesetvalueisexceeded,thesystemwillalarmtorealizethelivedetectionofthetransformerfault.Toacertainextent,onlinemonitoringreplacessomeconventionalpoweroutagepreventivetests.However,becauseonlinemonitoringcannotmeasuretheACparametersofpowerequipmentabovetheoperatingvoltage,itcannotobtaintheinsulationcharacteristicsunderDCvoltage.Therefore,centralizedreal-timemonitoringandportableonlinemonitoringarenowused,combinedwithconventionalpreventivetestswhenpowerequipmentisshutdown.02WorkshopⅠ.TransformerOilChromatographicOnlineMonitoringSystemUsingTransformerOilChromatographicOnlineMonitoringasanExample.TheinterfaceofthetransformeroilchromatographiconlinemonitoringsystemisshowninFigure4-16.Figure4-16

InterfaceoftransformeroilchromatographiconlinemonitoringsystemⅠ.TransformerOilChromatographicOnlineMonitoringSystemThetransformeroilchromatographiconlinemonitoringsystemconsistsofthefollowingthreeparts,asshowninFigure4-17.1.DataAcquisitionPrinciple:BymonitoringthedissolvedgasH2,CO,CH4,C2H6,C2H4andC2H2intransformerinsulationoilonline,thetypeandconcentrationofgasinthetransformeroilcanbedetected,therebydeterminingwhetherthetransformerhasfaultsorpotentialproblems.Figure4-17

Compositionofhigh-voltageonlinemonitoringsystemⅠ.TransformerOilChromatographicOnlineMonitoringSystemProcess:Thetransformeroilenterstheoilandgasseparationchamberforseparation.Theseparatedgaspassesth