预充电开关投切并联电容器合闸涌流抑制技术

电网中投入并联电容器时会产生合闸涌流,过大合闸涌流会诱发断路器分闸时的重击穿,危害电力系统的稳定运行、缩短用电设备的使用寿命。为此,提出一种预充电开关投切电容器的策略来抑制电容器投入电网时产生的合闸涌流,理论分析了预充电开关投切电容器的工作原理；提出了预充电开关投切电容器的电路模型；借助PSCAD仿真软件对预充电开关投切策略进行仿真验证,并分析了断路器的合闸时间分散性对合闸涌流抑制效果的影响。仿真结果表明,预充电开关投切电容器策略可以有效抑制合闸涌流,在准确合闸时可以将三相涌流分别减小至1.12p.u.、1.73p.u.和1.25p.u.,A相的合闸涌流可降低约70%,采用预充电开关投切电容器也大大缩短了合闸暂态过程持续的时间,证明了预充电开关投切策略的有效性。

Inrush Current Suppression Technology of Precharge-switch Switching Shunt Capacitors

When the shunt capacitors switched on in the power grid, high inrush current will occur and may cause restrikes of circuit breakers when switching off. The restrikes will harm the stability of the power system and shorten the working life of electrical equipment. A precharge-switch switching strategy is proposed to suppress the inrush current caused by capacitor switching on. The working principle of precharge-switch switching capacitors was theoretically analyzed, and the circuit model was proposed. A PSCAD simulation model was built to validate the proposed precharge-switch swtiching strategy, the closing time scatter of the vacuum circuit breaker was taken into consideration as well. The simulation results show that the inrush currents of three phase can be limited to 1.12p.u., 1.73p.u. and 1.25p.u.. The inrush current of A phase is reduced by about 70%, and the duration time of closing transient is sharply shortened. Thereby validate the effectiveness of the proposed precharge-switch switching strategy.