振荡中重合闸后加速保护研究

针对系统振荡时,后加速保护存在的单相重合时过于保守、而在三相重合时却又过于冒进等问题进行了分析,并依据三相重合闸以及单相重合闸的特点给出了一个重合闸后加速实现方案。由于三相重合闸检同期,在合闸后短时间内,通过检测线路相间最低电压来防止重合时由于线路负荷电流很大而造成的保护误动。此外,根据零序或负序电流是否大于线路无故障运行时最大不平衡输出,防止此后在后加速保护展宽的时间内因系统振荡而引起的保护误动。单相重合闸也通过检测不对称开放条件实现振荡中重合。ATP仿真以及动模数据分析证明了该方法的有效性。

Study on post-accelerating scheme of reclosing during power system oscillating

The delayed accelerated protection is too conservative during single-reclosing,while too rash during three-phase-reclosing in power swing,especially for the distance relaying.By analyzing this problem,a new delayed accelerated protection solution is proposed.In the new solution,considered the synchronization examination of three phase recloser,the lowest phase-to-phase voltage can be detected soon after reclosing.This voltage can be used to prevent the malfunction caused by heavy load current.In the mean time,the malfunction of protection caused by the oscillation of the power system during the broadening time of post-accelerating protection can also be prevented by checking whether the zero-sequence or negative-sequence current is heavier than the maximal unbalanced output current when the circuitry works well.The single-phase reclosing can also be closed by detecting the asymmetric open condition when the power system is oscillating.This scheme is proved to be valid by ATP simulation test and the analysis on dynamic analogue data.