三相重合闸对距离保护的影响

Influence of Three-phase Reclosing on Distance Protection

针对三相重合闸在交直流电力网络中重合不理想的问题,提出了一种关于故障距离、系统电抗、触发角等参数的新型重合方式,以提高电网供电的可靠性和安全性。根据AC-DC系统模型,分别推导出三相故障输电线路首、末端先重合时,距离保护的测量阻抗表达式,据此,分析整流侧与逆变侧系统电抗、临界点故障距离对保护的影响。考虑直流系统的控制模式和是否出现换相失败,分析测量阻抗随电压变化量和越前触发角的变化,得到不同情况下的最优重合方案。针对重合方案,采用两区域交直流电力网络和南方电网广东部分实际网络进行仿真,验证其结论的正确性和有效性。结果表明,新型的重合闸方案能够有效地减小距离保护出现误动作的风险,提高电力系统运行的安全稳定性。

In order to improve the reliability and security of power supply,a new reclosing method of fault distance,system reactance and trigger angle is proposed to solve the problem of unsatisfactory reclosing of three-phase reclosing in AC-DC power system.According to AC-DC system model when the three-phase fault occurs on the transmission line of the AC system,the distance protection expression is deduced in the head and the end coincide,and the influence of the rectifier side and inverter side system reactance,critical fault distance on the protection is analyzed.Considering control mode and the DC system has commutation failure,analysis of the variation trend with fire angle and fault voltage variation is done.It is concluded that the optimal coincidence scheme of the distance protection maloperation risk in AC-DC system is reduced.The correctness of the conclusion and effectiveness are verified by simulation of the Southern Power Grid and AC-DC system.The results show that the new reclosing scheme can effectively reduce the risk of distance protection and improve the safety and stability of power system.