電力電容器的局部放電測量課件

Lecture7

PDDetectioninPowerCapacitors1Contents1.PartialDischargeinPowerCapacitors電力電容器中的局部放電2.ParametersandStandard測試參數及相關規(guī)程3.ElectricalDetectionofPDinCapacitor電力電容器的局部放電電測法21.PartialDischargeinPowerCapacitors1.1thecharacteristicsofpowercapacitorsInsulationstructureofcapacitors:oil-impregnatedpapers,oil-impregnateddielectricmembraneandtheircombination.絕緣結構：油浸紙，浸漬薄膜及其組合Extremelyhighelectricalfieldstressexistsincapacitorsandpartialdischargesareverypossibletooccurinside.介質工作場強特別高，內部特別容易發(fā)生局部放電電力電容器的特點32.ParametersandSpecification2.1ParameterstoestimatethePDofcapacitorApparentcharge,qInceptionvoltage,UiTheACvoltageacrossthecapacitoratwhichthedischargemagnitudeexceedsagivenvalueqg.視在放電量升壓過程中，觀測到的放電量超過某個規(guī)定值時的最低電壓Inceptionvoltage(stress):TheACvoltage(stress)acrossthesampleatwhichdischargesstarttooccurwhenthevoltageisincreased.5Extinctionvoltage,Ue降壓過程中，觀測到放電量低于某個規(guī)定值的最高電壓值。TheACvoltageacrossthecapacitoratwhichthedischargemagnitudeislessthanthegivenmagnitudeqg.aisbetterthanb2.ParametersandSpecificationChangeofqwithvoltageapplyingtime放電量隨加壓時間的變化62.2ProcedureofPDdetection2.ParametersandStandardsU1:pre-appliedVoltage預加電壓

Type

U1(kV)

U2(kV)

U3(kV)

Requirement

Note

Shuntcapacitors

2.15un,1s

1.2un,10min

1.5un,10min

Series-connectedcapacitors

4.5un,1s

1.6un,10min

Breakercapacitors

1.8un,1s

1.1un,10min

Duringlast10min,noPDimpulseswithincreasedmagnitudeareobserved.

unisworkingvoltage.

U1

U2

U3

t1

t2

t3

U2:holdingvoltage保持電壓U3:measuringvoltage測量電壓73.ElectricalDetectionofPDinCapacitorThecapacityofapowercapacitorismuchlargerthantheusualHVequipments.LargecapacityofthepowersourceisrequiredforPDexperimentofcapacitors.

3.1PowerSourceandCircuits(1)PowersourceCompensationreactorisusedinseriesorparallelwithCxsothattodecreasethecapacityoftestingtransformerCurrentsthroughLandCwhilethetwoelementsconnectedinparallelVoltagesacrossLandCwhilethetwoelementsconnectedinseries試驗電源及回路電容器的容量比其他普通高壓設備大很多，因此所需的試驗設備容量也很大采用補償電抗器與試品串并聯(lián)的方式滿足實驗變壓器的容量要求9(2)Detectioncircuitse.g.Ck↗qs↘Cv↘3.ElectricalDetectionofPDinCapacitorsensitivity10ABalanceddetectioncircuitisrecommended3.ElectricalDetectionofPDinCapacitorThestraightdetectioncircuitsmaybeused.Inordertoobtainhighsensitivity,thecouplingcapacitorshouldbeatleastaslargeasthesample.Asecondsampleisusedasthecouplingcapacitor,Ck=Cx.采用直接測量回路，并用另外一個試品作為耦合電容使用平衡檢測回路11(2)Connectiontypesofcapacitorelementsinfluencedetectionresults.3.ElectricalDetectionofPDinCapacitor電容器元件的連接形式會影響檢測結果。13(3)TheinfluenceofinternalinductancePowercapacitorisnotpurecapacitance.Theinternalinductancecomesfrom:internalleads,leadingoutwires,capacitorelementsconnectinginseriesorparallel.L≈0.1~0.3μH電力電容器不是純電容設備，內部電感來自于：內部引線，引出線以及以串并聯(lián)連接的各個電容器元件本身。L≈0.1~0.3μHInfluencesonPDdetection:resul