不同工况下断路器过电压仿真及防护措施

针对近年来敞开式变电站内断路器雷击频繁损坏问题,在电磁暂态计算程序EMTP中建立计及工频电压和感应电压影响的仿真分析模型,仿真计算了断路器在不同工况下的过电压水平,分析了断路器损坏的原因,对比了两种不同方案的雷击防护效果。结果表明,断路器断开下遭受雷击产生的过电压是导致其绝缘击穿损坏的主要原因;对于500kV及以上电压等级线路,断路器绕击侵入波过电压较反击严重;雷击下断路器有效防护方式是在其线路侧安装无间隙避雷器,避雷器安装位置不宜直接套用规程的做法,可通过仿真计算后确定,本文研究结果可供相关人员参考。

Overvoltage Simulation and Protection Measures of Circuit Breaker Under Different Operation Conditions

In view of the frequent damage of circuit breaker caused by lightning in the air insulated switchgear(AIS)substation in recent years,the actual 500 kV AC substation-transmission line model considering the power frequency voltage and induced voltage is established in the electromagnetic transient program EMTP,then the overvoltage level of circuit breaker under different conditions is simulated,and the reason which causes the damage of circuit breaker is analyzed.Then a comparison of lightning protective effects between two different schemes is made.The results show that,the overvoltage caused by the lightning when circuit breaker is open is the main reason that leading to the insulation breakdown and damage of the circuit breaker.For lines with voltage levels of 500 kV or above,the intrusive overvoltage of circuit breaker is from shielding failure more serious than that from the back striking.The effective protective method of the circuit breaker under lightning is installing arrester without-gap at the circuit side of circuit breaker,and the method in relavent regulation should not be directly applied to determine the installation location of substation arrester,which could be determined after simulation.The results proposed in the paper can be used as reference to the actual engineering.