摘要
特高频局部放电在线监测装系统的内置传感器需嵌入气体绝缘金属封闭开关设备(Gas Insulated Switchgear,GIS)壳体内部,若内置传感器自身出现局部放电,不仅难以对其进行检修更换,还会导致对设备运行状况的误判,因此亟须对内置传感器自身放电的信号特征及检测方法进行研究分析。针对一起特高压GIS内置传感器监测到的局部放电缺陷,通过局部放电定位及现场检查,判断为内置传感器馈线末端绝缘减弱导致的芯线对屏蔽层放电,且示波器观察到的放电信号存在明显的折反射过程。结合波传导理论分析可知,芯线对屏蔽层放电后,由于两者间的耦合作用使得同轴电缆的波阻抗发生改变,从而与示波器端口阻抗失配,导致特高频信号在同轴电缆上发生折反射。因此,将示波器检测图谱中的折反射特征作为内置传感器馈线处局部放电的判据。实际检测情况表明,所提GIS特高频局部放电内置传感器自身放电缺陷分析方法对判别局部放电信号位于GIS内部还是内置传感器馈线处具有一定指导作用。
The inner sensor of ultra ligh freguency(UHF)partial discharge(PD)on⁃line monitoring system needs to be embedded in the gas insulated switchgear(GIS)shell.If the inner sensor has partial discharge,it will not only be difficult to repair and replace it,but also lead to misjudgment of equipment operation status.Therefore,it is necessary to study and analyze the signal characteristics and detection methods of the inner sensor self⁃discharge.In view of a partial discharge defect detected by the inner sensor of ultra high voltage(UHV)GIS,it was judged that the core wire was discharged to the shielding layer through the partial discharge location and on⁃site inspection,which was caused by the weakened insulation at the end of the feeder of the inner sensor,and the discharge signal observed by the oscilloscope had obvious catadioptric process.Combined with the theoretical analysis of wave conduction,it could be seen that the wave impedance of coaxial cable changed due to the coupling effect between the core wire and the shielding layer,which caused the impedance mismatch between the coaxial cable and the oscilloscope port,resulting in the reflection of UHF signal on the coaxial cable.Therefore,the refraction and reflection characteristics in the oscillograph detection spectrum can be used as the criterion of partial discharge at the feeder of the inner sensor.The proposed method of GIS UHF inner sensor self⁃discharge has a certain reference and guiding role in distinguishing whether the partial discharge signal is located in the GIS or at the feeder of the inner sensor.
作者
张丕沛
王江伟
李杰
ZHANG Pipei;WANG Jiangwei;LI Jie(State Grid Shandong Electric Power Research Institute,Jinan 250003,China)
出处
《山东电力技术》
2021年第9期28-32,68,共6页
Shandong Electric Power
基金
国家电网公司总部科技项目“融合高速光学成像与局放信号检测的GIS设备内部金属异物检测技术研究”(520626210032)。
