温度对GIS绝缘子表面金属异物局部放电及闪络特性的影响

Influence of Temperature on Partial Discharge and Flashover Characteristics of Metal Particle on GIS Insulator Surface

表面金属异物是造成气体绝缘全封闭组合电器(gas-insulated switchgear,GIS)绝缘子故障失效的重要原因。运行中的绝缘子不仅承受强电场作用,还承受温度场的作用,研究电–热耦合下绝缘子表面金属异物的局部放电和闪络特性,具有重要的实际意义。鉴于此,该文建立GIS绝缘子电场和温度场耦合试验平台,开展不同温度作用下绝缘子表面金属异物缺陷的局部放电和闪络特性研究。结果发现,绝缘子表面最高温度从25℃升高至75℃时,绝缘子表面2.5cm长金属异物缺陷的局部放电起始电压降低约16%;平均放电量从0.55pC增加至1.45pC;最大放电量从9.1pC增加至11.5pC;放电频次也从不足200次/s增加至近400次/s。不同电压下,不同尺寸金属异物局部放电特性随温度变化的规律基本一致;而温度对绝缘子表面金属异物缺陷的工频闪络电压的影响不显著。研究结果有助于进一步认识实际运行中在电–热耦合作用下,温度变化对绝缘子表面金属异物缺陷的局部放电和闪络特性的影响规律。

The metal particle on the insulator surface is an important cause of GIS insulator failure.In field operation,the insulators work is not only under electric stress,but also under temperature gradient.Therefore,it is of great significance to study the partial discharge(PD)and flashover characteristics of insulator surface defects under electrothermal coupling effect.In this paper,the electrothermal coupling experiment platform was established to study the PD and flashover characteristics of metal particles on the insulator surface under different temperature.The results show that when the maximum temperature of the insulator increases from 25℃to 75℃,the PD inception voltage(PDIV)of metal particles decreases by about 16%,and the average and maximum apparent charge of PDs increased from 0.55 pC and 9.1 pC to 1.45 pC and 11.5 pC respectively,while the discharge repetition rate also increases from less than 200 times/s to nearly 400 times/s.However,the temperature has little effect on the flashover voltage.This paper is helpful to understand the influence of temperature on the PD and flashover characteristics of metal particle defects on insulator surface under electrothermal coupling effect.