双回线并线后距离保护自适应方法及仿真计算

An Adaptive Distance Scheme Considering Double Transmission Line Shunt to One Transmission Line

针对由双回线并接为一回线路运行时距离保护出现超越的现象,分析了各运行状态下测量阻抗出现偏差的原因,获得测量阻抗解析解,进而提出一种自适应保护方法,该方法可在不同运行状态下,依据测量阻抗解析解实时调整距离保护方案;同时,对于线路末端测量阻抗的下降趋势,加入故障相电压闭锁,防止线路末端保护误动。利用PSCAD在实际220kV系统中的仿真结果表明,该方法正确、有效。

This paper considers the phenomenon that the distance relay becomes over reach or under reach when the 220 kV grid transmission transform from double line to one line. The reason for appearance of impedance deviation is ana- lyzed. Then the analytical results of the impedance in different operating condition are obtained. Thus, an adaptive pro- tection method is put forward. The method can adjust real time distance protection scheme by the analytical results of the impedance under different operating conditions. As the impedance at the end of line has the falling tendency, the end of line malfunction is protected by adding fault phase voltage lockout. The simulation of actual 220 kV system is implemen- ted in the PSCAD. The results show that the proposed method is correct and effective.