电力电容器局部放电课件.ppt

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1、Lecture7PDDetectioninPowerCapacitors电力电容器的局部放电测量1Contents1.PartialDischargeinPowerCapacitors电力电容器中的局部放电2.ParametersandStandard测试参数及相关规程3.ElectricalDetectionofPDinCapacitor电力电容器的局部放电电测法21.PartialDischargeinPowerCapacitors1.1thecharacteristicsofpowercap

2、acitorsInsulationstructureofcapacitors:oil-impregnatedpapers,oil-impregnateddielectricmembraneandtheircombination.绝缘结构：油浸纸，浸渍薄膜及其组合Extremelyhighelectricalfieldstressexistsincapacitorsandpartialdischargesareverypossibletooccurinside.介质工作场强特别高，内部特别容易发生局

3、部放电电力电容器的特点31.2InceptionanddamageofPDinpowercapacitor1.PartialDischargeinPowerCapacitorsThelifetimeofcapacitorsufferingfromPDdecreasesexponentially.PDisakeyfactorthatresultsinexpandingandincipientfaultofpowercapacitor.在局部放电作用下，寿命是随着电场的增加而呈指数形式下降的局部放电是

4、造成电容器膨胀和早期损坏的一个重要因素42.ParametersandSpecification2.1ParameterstoestimatethePDofcapacitorApparentcharge,qInceptionvoltage,UiTheACvoltageacrossthecapacitoratwhichthedischargemagnitudeexceedsagivenvalueqg.视在放电量升压过程中，观测到的放电量超过某个规定值时的最低电压Inceptionvoltage(st

5、ress):TheACvoltage(stress)acrossthesampleatwhichdischargesstarttooccurwhenthevoltageisincreased.5Extinctionvoltage,Ue降压过程中，观测到放电量低于某个规定值的最高电压值。TheACvoltageacrossthecapacitoratwhichthedischargemagnitudeislessthanthegivenmagnitudeqg.aisbetterthanb2.Para

6、metersandSpecificationChangeofqwithvoltageapplyingtime放电量随加压时间的变化62.2ProcedureofPDdetection2.ParametersandStandardsU1:pre-appliedVoltage预加电压TypeU1(kV)U2(kV)U3(kV)RequirementNoteShuntcapacitors2.15un,1s1.2un,10min1.5un,10minSeries-connectedcapacitors4.

7、5un,1s1.6un,10minBreakercapacitors1.8un,1s1.1un,10minDuringlast10min,noPDimpulseswithincreasedmagnitudeareobserved.unisworkingvoltage.U1U2U3t1t2t3U2:holdingvoltage保持电压U3:measuringvoltage测量电压7Powersource:sinewave,50Hz,60HzThecapacitancedifferencebefore

8、andaftertestshouldnotexceedthedifferencecausedbyafuseburningout.Asimulatingsmallcapacitorscanbeusedwhensensitivityorcapacitycouldnotmeetthetestrequirements.2.ParametersandStandards试验电压为正弦波，频率为50或60Hz测试前后测量电容，两次测量值之差不能超过一根熔丝断开的差值如果被试电容器的电容值太大，在