特高压直流极母线避雷器污秽状况下内外部电场分布的仿真研究

Simulation study of internal and external electric field of UHV DC polar bus arrester under pollution conditions

由于直流电场对污秽颗粒的吸附作用,使直流避雷器相对于交流避雷器的积污更加严重。且特高压直流极母线避雷器在绝缘外套内部还有3柱并联的电阻片柱,污秽分布对绝缘外套表面电场以及电阻片柱与绝缘外套之间的径向电场的改变,都将会对避雷器的运行状况造成一定的影响。文章结合直流场中污秽的分布特点,建立了特高压直流极母线避雷器污秽状况下的电场仿真模型,对避雷器在整体湿污秽以及出现局部干燥带时的伞裙表面电场和电阻片柱与绝缘外套间的径向电场进行了计算分析。结果表明,避雷器整体污秽会导致绝缘外套表面场强与内部径向场强的增大,但数值较小尚且不会引起电晕及闪络现象;而局部干燥带的出现,则会在伞裙表面和电阻片与绝缘外套间的空气间隙形成局部过高的表面场强和径向场强,导致绝缘外套表面闪络,以及电阻片柱与绝缘外套间的贯穿性放电等现象,严重危害避雷器的安全稳定运行。

Because of the adsorption of pollution particles by DC electric field,the pollution of DC arrester is more serious than that of AC arrester.The UHV DC polar bus arrester also has three parallel resistor columns inside the insulation jacket,so the change of the surface electric field of the insulating jacket and the radial electric field between the resistor columns and the insulating jacket will have a certain impact on the operation of the arrester.According to the characteristics of pollution distribution in DC field,the electric field simulation model of UHV DC polar bus arrester under pollution is established in this paper.The electric field on the surface of umbrella skirt and the radial electric field between resistor columns and insulating jacket are calculated and analyzed when the overall pollution is not uniform and the local drying zone occurs.The results show that overall pollution of the arrester will lead to the increase of the surface electric field of insulating jacket and internal radial electric field,but the smaller value will not cause corona and flashover.However,the appearance of local drying zone will result in excessive surface flashover and redial field strength on the surface of umbrella skirt and the air gap,and the perforation discharge between resistor columns and insulating jacket,which will seriously endanger the safe and stable operation of the arrester.