并联电容器零序电压保护的改进方法分析

并联电容器零序电压保护是通过检测零序电压来判断电容器组内部是否出现故障,从而给出报警信号或者跳闸信号使电容器组退出运行。零序电压保护不能识别故障相,不能消除三相电压不平衡的影响。为克服这些缺陷,对电容器零序电压保护进行了改进方法的研究,分析了电容器组内部故障时的过电压和相电流的变化,并给出了计算公式。同时,提出了消除三相电压不平衡及识别故障相的改进方法。

Analyze of Zero Sequence Voltage Protection Scheme for Shunt Capacitor Bank

Shunt capacitor zero sequence voltage protection can judge whether the outage of internal capacitor elements in banks by detecting zero sequence voltage to send a warning signal or a trip signal for the banks′ breaker to remove the bank from the system.Zero sequence voltage protection fails to identify the faulted phase and to wipe out the influence of three phase unbalance voltage.In order to overcome its disadvantages,a study of mended zero sequence voltage protection scheme for shunt capacitor is made.This paper analyses the internal over voltage and changes of the phase current,and gives corresponding equations.At the same time,it gives a developed method about eliminating the three phase unbalance voltage and identifying the fault phase.