中文摘要：

发现合于永久故障时三相重合闸时刻对系统暂态电压稳定性有较大影响,并以无穷大、单负荷系统为例研究其原因.在感应电动机动态负荷模型下,考虑故障点位置变化,推导出交流线路从发生三相短路、线路三相跳闸、三相重新合闸于永久故障,到最后的三相断路器跳闸的全过程中,负荷侧母线电压及电磁转矩的变化情况.通过对上述暂态过程中电磁转矩-转差率的变化规律发现,最后一次操作完成后,运行点距离新的稳定平衡点越近,越有利于系统的暂态电压稳定.并结合对实际电网中的仿真结果指出,若在转差率增大的过程中投入重合闸,再次故障产生的减速能量会使转差率继续增大,对系统的暂态电压稳定性将产生不利影响.

英文摘要：

The effect of three-phase re-closure time on system＇s transient voltage stability is larger when it is reclosed to permanent disturbance. Single load infinite bus system is taken as an example to discuss its mechanism. Under inductive motor dynamic load model,voltage of load bus and electromagnetic torque during the whole process from permanent fault occurrence to three-phase breaker tripping,re-closure to permanent fault and till three phase breakers tripping again are calculated and analytic expression of which are derived. By analyzing the changing of electromagnetic torque to slip ratio,it is discovered that it is beneficial for the transient voltage stability of the system if the operation point is near the stability balanced point when the last operation has finished. According to the simulation result of actual power grid,it is pointed out that transient voltage stability will decrease if reclosure during the process of slip ratio is increasing.