500 kV交流滤波器断路器均压电容器径向击穿仿真分析

Simulation of Radial Breakdowns on the Breaker Grading Capacitor of 500 kV AC Filter

为查明某换流站交流滤波器断路器均压电容器径向击穿的故障原因,利用ATP/EMTP对换流站第四大组交流滤波器进行建模,同时考虑均压电容器电容分布及外部污秽的影响,计算故障均压电容器绝缘筒内外壁电位差、故障点与断路器静触头电位差。仿真结果表明:均压电容器壁厚不足和外部污秽是导致径向击穿的根本原因。最后,采用三维有限元法仿真计算均压电容器内外电场分布,提出增加均压电容器壁厚或改用瓷外套均压电容器的整改方案。

In order to find out the cause of radial breakdown on the breaker grading capacitor of 500kV AC filter in a converter station,the simulation model of the fourth group AC filter of converter station is set up by ATP/EMTP.Tak- ing into account the influence of the capacitance distribution and external contamination of the grading capacitor, the potential differences are studied within different positions,such as internal and external surface of the fault grad- ing capacitor,the fault place and the static contact.The calculation results show that the main causes of radial break- downs are insufficiency of wall thickness of the breaker grading capacitor and external pollution.Finally,the internal and external electric field distributions of the grading capacitor are analyzed by three-dimensional finite element meth- od.The improvement program including increasing the thickness of the grading capacitor or changing into the porce- lain grading capacitor are put forward.