高速荷电沙尘环境中环氧树脂绝缘子的闪络特性

Flashover Characteristics of Epoxy Resin Insulator in High-speed Charged Sand Environment

为探明高速荷电沙尘环境下车顶绝缘子的闪络特性,依托自建的高速风洞试验系统与沙尘荷质比测量装置进行了高速气流、高速沙尘及高速荷电沙尘环境下环氧树脂绝缘子闪络试验,并结合仿真进行了机理分析。结果表明:在高速气流环境中,气吹效应与气流密度效应的联合作用是影响绝缘子闪络电压的主导因素,致使闪络电压随风速呈现先增加后下降再上升的特殊变化趋势;在高速沙尘及高速荷电沙尘环境下(风速>18m/s),绝缘子闪络电压相比于高速气流环境整体依次下降,且闪络电压均随风速增加呈现先下降后上升的趋势,但其变化趋势随风速逐渐变缓,其主要原因是由于在该环境下沙尘及荷电沙尘已经成为影响绝缘子闪络电压的主要因素。沙尘环境中闪络电压随着进沙口沙质量流量的增加呈下降趋势。此外,当沙尘荷电后,绝缘子周围电场发生畸变,电场不均匀度显著增加,导致闪络电压大幅降低,且闪络电压随着沙尘荷质比的增加呈线性下降趋势。以上研究可为高速荷电沙尘环境中列车车顶高压绝缘设计与防护提供借鉴。

To ascertain flashover characteristics of the roof insulator in a high-speed charged sand environment, we experimentally investigated the flashover characteristics of epoxy resin insulator in environments of pure high-speed airflow, high-speed sand, high-speed charged sand based on an artificial experimental wind-tunnel platform and charge-mass ratio measurement device of dust. Moreover, we analyzed the influences of airflow speed, sand and charged sand on the flashover characteristics of epoxy resin insulator by simulation. Results show that, in the pure high-speed airflow environment, the flashover voltage of insulator has an increase-decrease-increase variation trend with the increase of airflow speed. The flashover mechanism is due to the combined effects of airflow blowing effect and airflow density. In high-speed sand and high-speed charged sand environment, the flashover voltages decrease in turn compared with that in pure high-speed airflow environment with a decrease-increase variation trend(airflow speed>18 m/s). However, the variation trend with the increase of airflow speed will slow down because sand and charged sand have negative influences on the flashover voltage of insulator. In the high-speed sand environment, the flashover voltages decrease with the increase of the sand flux. Additionally, the nonuniformity of the electric field around the insulator increases remarkably which leads to the decrease of flashover voltage significantly. The flashover voltage decreases linearly with the increase of charge-mass ratio of sand. These research results can provide a reference for design and protection of roof insulators in the high-speed charged sand environment.