特高压换流站复合支柱绝缘子伞伸出对其高海拔直流污闪性能的影响

Influence of Shed Overhangs of Composite Post Insulators in UHV Convert Stations on DC Flashover Performances at High Altitude

为了研究高海拔地区伞伸出对复合支柱绝缘子直流污闪电压的影响规律,选取一大一小和一大两小两种伞形结构的10种伞伸出参数复合支柱绝缘子,在海拔2 100 m的条件下,采用恒压升降法进行人工污秽试验,研究伞伸出参数对复合支柱绝缘子污闪电压的影响,同时测量了试品单元伞裙表面电阻在雾室随时间的变化,用紫外放电仪和高速摄像机观测试品的临闪前局部放电和沿面电弧发展。研究结果表明:试品污闪电压值随着平均伞伸出增大存在最大值,提出了平均伞伸出与污闪电压值的二次函数关系;由于绝缘子表面电阻随着伞伸出的增大而减小,临闪前局部放电现象趋于明显,表面电弧桥接概率加大,电弧"飘弧"现象严重,大大降低了爬距利用率,导致污闪电压值下降。

To investigate the influence of shed overhang of post composite insulators on flashover performance at high altitude, artificial pollution tests on 10 types of post composite insulators with different shed overhangs were carried out at high altitude area （2100m）; the surface resistance of one shed unit was measured, and the ultra violet（UV）camera and the high speed camera Phantom were used to observe the partial discharge before flashover and the development of arcs on the insulator surface. The results show that, with the increase of shed overhang, the flashover voltage increases at the beginning and then decreases; the relationship between the average shed overhang and the flashover voltage was proved approximate quadratic function. Moreover, with the increase of shed overhang, the surface resistance also decreases in the fog chamber, and the partial discharge phenomenon tend to be much more intensely, the arc on the surface became much more easily bridges the sheds in the process of flashover, and this leading to decline the utilization rate of creepage distance, so the flashover voltage decreased.