同塔双回线接地故障断路器误动的改进策略

Improving Strategy of Ground Fault Mal-operation of Circuit Breaker with Double-circuit Transmission Line in the Same Tower

双回输电线发生接地故障时,存在受助增或分汲影响的零序电流可能满足非故障线路高灵敏度零序反时限保护定值导致断路器误动的问题。针对该问题,文中分析了高压交流系统中双回线路发生接地故障时零序电流的分布机理及相邻非故障线零序反时限过流保护可能误动的原因。提出了一种高灵敏接地距离判据来提高零序反时限过流选择性,结合判据和电流分布特征提出了零序反时限过流自适应加速策略,该方法通过自适应改变零序加速系数保证故障线优先动作,避免相邻非故障线保护误动导致断路器无序动作。仿真结果表明,零序反时限过流保护优化推动了其定值一致性整定的可行性,降低了相邻非故障线断路器误动风险。

In case of ground fault in a double-circuit transmission line,there is the problem that the zero-sequence current due to the increase or splitting may meet the high-sensitivity zero-sequence inverse-time limit protection setting of non-faulted lines and cause the circuit breaker in mal-operation. In view of this problem,the distribution mechanism of zero-sequence current in the case of a ground fault on a double-circuit line in a high-voltage AC system as well as the cause of possible mal-operation of the zero-sequence inverse-time over-current protection of adjacent non-fault lines are analyzed.A highly sensitive ground distance criterion is proposed to increase the zero-sequence inverse-time limit over-current selectivity. Combining the criteria and current distribution characteristics,a zerosequence inverse-time limit over-current adaptive acceleration strategy is proposed.In this method,the zero-sequence acceleration coefficient is adaptively changed to ensure the priority action of the fault line,and to avoid disorderly mal-operation of circuit breaker of adjacent non-fault line protection. The simulation result shows that the optimization of the zero-sequence inverse time-over-current protection optimization promotes the feasibility of its setting consistency,and reduces the risk of mal-operation of adjacent non-fault line circuit breakers.