一起800kV断路器合闸后接地故障原因分析

Analysis of a ground fault for 800 kV circuit breakers closed

针对S变电站运行过程中发生的一起800 kV SF6断路器接地故障,通过现场二次保护动作、故障录波图中电压与电流变化趋势以及SF6分解产物等分析,确定了故障断路器间隔。通过返厂解体,发现了设备内部放电过程中受损部件以及相应的放电轨迹。基于故障后气室材料特性分析、合闸电阻堆热容量分析、设备放电轨迹分析,确认放电原因为罐体内部异物。通过断路器合闸过程中的粒子飞行轨迹分析、罐体内异物电场仿真、电阻堆气隙内电场仿真,给出了2种异物来源,并提出了相应的异物解决措施,以避免同类接地故障的发生。

In view of an abnormal ground fault of an 800 kV SF6 circuit breaker occurred during the operation of S substation,this paper confirmed the fault circuit breaker through the analysis of the secondary protection action,the variation trend of fault recording voltage and current,and the components of SF6 decomposition. The damaged parts in the discharge process and the corresponding discharge trajectories were found by disintegration. Based on the analysis of the material characteristics of the gas chamber after the fault,the explosion and crack analysis of the pre-insertion resistors,and the discharge trajectory analysis,the electric field distortion caused by the foreign body inside the tank was confirmed as the cause of the fault. At last,two kinds of foreign bodies were identified by particle flight path analysis and air gap electric field simulation analysis in the circuit breaker closing process,and corresponding solutions were given.