染污绝缘子表面流注放电特性的实验研究

Experimental Study on Streamer Discharge Characteristics Along Contamination Insulator Surface

为了研究绝缘子表面污秽对流注传播的影响,在海拔高度为2 100 m的特高压实验基地,利用3电极结构进行了实验研究,比较了涂覆不同盐密和灰密污秽的绝缘子上的流注传播特性,并用Ansoft电磁场分析软件对涂覆污层前后绝缘子表面的电场分布进行了仿真计算。实验结果表明:流注的稳定传播电场强度随盐密的增大而先增大,在盐密超过0.10 mg/cm2后保持不变,随灰密的增大而升高;在外加电场强度大于稳定传播电场强度后,相同电场强度下,变化污秽层盐密、灰密对应的流注传播平均速度相差不大。通过仿真计算发现:污层的存在使得绝缘子表面的电场分布发生畸变,污区的电场明显减弱,污层两端电场增强;污层电导率的变化使得电场分布改变,从而导致涂污前后绝缘子表面流注放电脉冲波形在盐密、灰密变化时的稳定传播电场强度变化。

In order to investigate the influence of surface contamination on the streamer propagation on insulators, in a UHV Experimental Base at an altitude of 2 100 m in China, using a three-electrode structure, we experimentally investi- gated and compared the characteristics of streamer propagation on insulators covered with contaminations of different ESDD and NSDD. We also calculated the electric field distribution on insulator surface before and after being contami- nated through simulations in Ansoft. The experiments show that Est （the applied electric field sustains stable streamer propagation） increases with ESDD until ESDD reaches 0.10 mg/cm2, then it stays the same, but it keeps increasing with NSDD. When the applied field exceeds Est, the propagation velocity of streamer on surfaces with different ESDD and NSDD is the same. From the simulation, it is found that the presence of contamination distorts the electric field on insu- lator surface, and the electric field is obviously reduced in contaminated area but enhanced on both ends of the contaminated area. In conclusion, the change in conductivity of contamination due to different ESDD and NSDD changes the electric field distribution on insulator surface, and then causes the surface streamers to have changes in their current waveforms and hence in their Est.