500kV交流线路断路器短路电流延时过零现象研究

Research on Zero Offset of Short Circuit Current Occurred in Circuit Breaker for 500 kV AC Transmission Line

高压交流断路器切断电流时均在电流过零时才能灭弧,电流延迟过零现象会加重高压断路器的开断负担,并可能造成断路器损坏。为此以伊敏换流站500 kV 5043交流线路断路器现场实际故障为例,通过理论分析及仿真计算研究了交流线路发生单永故障重合期间,交流线路断路器出现短路电流延时过零现象的机理及条件,并得出判断阀值;指明该故障工况若出现在发电厂密集地区,相应线路断路器延时过零现象的概率较大;分析了交流线路断路器不同重合时刻对断路器短路电流的影响。同时,根据伊敏地区交流线路重合闸设备现有功能设置,提出了适用于现场实际的避免流经断路器的短路电流延时过零的反故障策略。

During the switching-off of fault current in 500 kV transmission line by circuit breaker, the arc can only be extinguished at the zero-crossing point of fault current, and the zero offset of fault current will make the burden of switching-off fault current heavier and lead to the damage of circuit breaker. Taking the actual fault of a certain 500kV AC circuit breaker near Yimin converter station for example, the mechanism and conditions of occurring zero offset of short circuit current during the reclosure of AC transmission line, in which the single-phase permanent fault happened, are theoretically analyzed and simulated, and the judgment threshold for it is obtained; it is pointed out that when the fault condition occurs in the region where power plants are located, the occurrence probability of zero offset in the circuit breakers for corresponding transmission lines is higher; the impacts of different reclosing time of circuit breaker for AC transmission line on short circuit current flowing through circuit breaker are analyzed. Meanwhile, based on existing function setting of reclosure equipments for AC transmission lines in Yimin region, an anti-failure strategy to avoid the zero offset of short circuit current flowing through circuit breaker is proposed.