基于故障分量综合阻抗的T接线路纵联保护新原理

Principle of T-type transmission line pilot protection based on fault component comprehensive impedance

提出了一种适用于T接线路的基于故障分量综合阻抗的纵联保护新原理,利用故障时线路三端电压故障分量相量之和与电流故障分量相量之和的比值来判断线路上是否发生了故障。外部故障时,该比值反映线路的容抗,其模值较大;内部故障时,该比值反映系统电源阻抗和线路阻抗,其模值相对较小,据此可以区分线路上的内部和外部故障。根据新原理构成的保护不需要对电容电流进行补偿,可用于带或不带电抗器补偿的线路,在原理上不受过渡电阻的影响,而且当T接线路内部发生故障而有汲出电流时,保护的灵敏度也不受影响。EMTP仿真验证了新原理的有效性。

A new pilot protection principle based on fault component comprehensive impedance is proposed for T-type transmission line,which uses the ratio of the sum of three terminal component voltage phasors to the sum of three terminal current phasors of the same line to detect the line fault. When an external fault occurs,the ratio is large,reflecting the capacitive impedance of line;when an internal fault occurs,the ratio is relatively small, reflecting the impedance of both system source and line,by which the external fault is distinguished from internal one. The protection with this new principle needs not to compensate the capacitive current,suitable for line with or without shunt reactor. It is not influenced by the transition resistance and its sensitivity is not influenced by the out-flowing current during the internal fault of the T-type line. Simulation with EMTP verifies its effectiveness.