并联电容器组电容量变化对不平衡电流保护的影响分析

Influence Analysis of Capacitance Change of Shunt Capacitor Bank on Unbalance Current Protection

针对一起并联电容器组不平衡电流保护动作事件,分析单台电容器电容量变化对不平衡电流保护的影响。经分析与推导,得出了电容器组的接法及电容器故障率与不平衡电流之间的关系,并对其作了验证。分析结果表明,虽然单台电容器的电容值变化在规程允许范围内,但同时出现多台电容器击穿时,不平衡电流仍然会达到定值,从而导致不平衡电流保护动作。最后,提出了防范同类事件发生的相关建议。

Aiming at an action event of unbalance current protection of shunt capacitor bank, the influence of the change of capacitance value of single capacitor on the unbalance current protection is analyzed. By analysis and derivation, the relationship among the connection of capacitor banks, the fault rate of capacitor and unbalance current are obtained and testified. Analysis results show that although the change of capacitance value of single capacitor is within the allowed range of regulation, the unbalance current will still reach the setting value and cause the action of unbalance current protection when the breakdown of multiple capacitors happens at the same time. Finally, corresponding suggestions to prevent similar events happening are proposed.