直流GIL绝缘子表面附着金属颗粒局部放电发展过程及严重程度评估

Evolution Process and Severity Assessment of the Partial Discharge Caused by Immobilized Metal Particles on DC GIL Insulator Surface

直流气体绝缘线路(gas insulated line,GIL)绝缘子表面附着金属颗粒会显著降低绝缘子表面的闪络电压,是GIL设备内一种常见的故障。为研究直流GIL绝缘子表面附着金属颗粒所引发局部放电的发展过程并进行严重程度判断,建立了一套220 kV GIL设备局部放电测试平台,在逐步升压时利用紫外观测仪观察了绝缘子表面局部放电的整个发展过程,对不同发展阶段局部放电脉冲电流信号的局部放电量、局部放电间隔时间图谱进行了分析。结果表明:GIL绝缘子表面附着金属颗粒导致的局部放电严重程度可以划分为3个阶段:轻微放电、中度放电和严重放电;随着放电过程的加剧,局部放电信号的局部放电量、局部放电间隔时间图谱跟随出现变化。利用局部放电信号的局部放电量、局部放电间隔时间图谱统计参数Sk、Ku值可以对GIL绝缘子表面附着金属颗粒缺陷引发局部放电的严重程度进行评估。

Immobilized metal particles on DC GIL insulator surface significantly reduce the flashover voltage on theinsulator surface,which is a common defect in DC GIL. To study the evolution process and severity assessment ofpartial discharge caused by immobilized metal particles on DC GIL insulator surface,we established a 220 kV GIL equipment platform. By gradually increasing voltage and then using the ultraviolet viewer observed the entire partialdischarge evolution process on insulator surface. Meanwhile,analyzed the average amplitude and time interval ofpartial discharge. The results show that：the severity of partial discharge caused by the immobilized metal particles inthe insulator surface of the GIL can be classed into three levels： mild discharge,moderate discharge and severedischarge;as the discharge process intensified,the average amplitude and time interval of partial discharge followedthe change. The statistical parameter Sk/Kuof average amplitude and time interval of partial discharge can be used toevaluate the severity of the defect caused by immobilized metal particles on DC GIL insulator surface.