基于高压直流换流站站域信息的交流线路距离保护方法

摘要

为了解决发生换相失败时基于工频相量的交流线路距离保护将会受到影响而无法可靠判别故障的难题,提出了一种基于高压直流换流站站域信息的交流线路距离保护方法.因为未发生换相失败期间,距离保护可以准确地识别故障位置,所以可以考虑在换相失败期间闭锁距离保护,以避免其受到换相失败的影响.逆变器正常换相时,直流侧电流与交流侧电流基本相等,而换相失败时直流侧电流将远大于交流侧电流,利用此故障特征可对换相失败进行检测.基于换流站站内换相失败信息的检测与共享,可对传统距离保护的性能进行改善.在 PSCAD/EMTDC 仿真环境下建立高压直流输电系统模型,对所提出保护方法的性能进行验证.仿真结果表明,新提出的距离保护可以避免换相失败对其的影响,在交流线路区内、外发生不同类型的故障时均能准确、可靠地判别故障位置.%In order to solve the problem that the traditional distance protection for AC transmission lines is influenced by commutation failure, a novel distance protection based on substation area information sharing is proposed in this paper. The distance protection can detect the fault position correctly when commutation failure do not occur. Thus, to avoid the influence of commutation failure, the distance protection can be blocked when the commutation failure is detected. The current at inverter DC side is approximately equal to the current at AC side when the inverter commutates normally, and the DC current will be larger than the AC current when commutation failure occurs, which can be used to recognize the commutation failure. Based on the detection and sharing of commutation failure information, the traditional distance protection can be improved. A HVDC system model is built in PSCAD/EMTDC simulation environment to test the performance of the improved method. Simulation results show that the novel method can detect the internal and external faults correctly when different types of faults occur, avoiding the influence of commutation failure.