气体绝缘开关中表面金属异物长期局部放电稀疏性特征的观测

Observation on the Characteristics of Long-Term Partial Discharge Sparseness of Surface Metal Particle in Gas Insulated Switch

气体绝缘开关(GIS)绝缘故障统计数据显示,表面金属异物缺陷在绝缘故障中占比最高,而工程中通过局部放电手段检测到的缺陷多为绝缘件气隙和悬浮放电,少有表面金属异物案例,两者之间的不一致,说明了当前的现场局部放电检测方法对金属异物表面缺陷检测的有效性有待研究。为此,本文设计GIS绝缘子表面金属异物缺陷,施加恒定电压,基于全实时特高频信号检测系统,研究模型放电的长期发展过程,揭示表面金属异物在长期发展阶段中稀疏性特征,即放电区间分散度大、间隔跨度自数秒至数小时不等。提出有效放电捕捉概率Pe和有效图谱捕捉概率PG两项评估参数,通过Pe、PG曲线,给出了现有的GIS设备在线监测装置对放电事件捕捉成功率较小(仅有3.4%),以及带电检测得到有效图谱概率较低(仅有6.5%)的事实。在此基础上,提出加强实时采集系统推广和延长检测时长等提高放电检出率的方法。

According to gas insulated switch insulation failure statistics,the surface failure accounts for the highest proportion.However,the defects detected by partial discharge are mostly air gaps and floating discharges,and the cases of surface discharge are rarely found.It is essential to study the effectiveness of the current on-site PD detection method for the detection of surface discharge defects.This paper designed a metal particle attached to the GIS insulator.Under the condition of constant voltage application,based on the full real-time UHF detection system,the long-term development process of the model discharge was studied.The sparsity characteristics of the surface metal particle in the long-term development stage were revealed,including the large dispersion of the discharge interval,varied from several seconds to several hours.The evaluation parameters of effective discharge capture probability Pe and effective spectrum capture probability PG were proposed.Through the Pe and PG curves,it was found that the existing GIS equipment online monitoring device had a small success rate(only 3.4%)for the surface discharge capture,and the probability of live detection capturing was low(only 6.5%).On this basis,a method to enhance the detection rate of the real-time acquisition system and extend the detection duration was proposed.