相控断路器投切10kV并联电容器的应用

Application of 10 kV Switching Shunt Capacitor Banks with Controlled Vacuum Circuit Breakers

近年来,变电站真空断路器投切10 k V并联电容器组时发生了多起断路器或电容器炸裂事故,在更换断路器和改善保护措施后,此类事故还是屡禁不止。为减少该工况下绝缘事故的发生,重庆市某110 k V变电站采用分相控制技术的永磁机构真空断路器来抑制投切电容器组时的合闸涌流和降低分闸重燃概率。相控断路器是抑制并联电容器合闸涌流与分闸过电压的重要措施之一。为了验证该技术的有效性,首先基于电路理论分析了合闸角对合闸涌流的影响以及分闸过电压机理,之后在重庆市某110 k V变电站针对某种型号相控断路器与普通真空断路器合(分)闸10 k V并联电容器进行了一系列的现场试验研究。试验结果表明:相控断路器的控制精度高(合(分)闸误差均在±0.3 ms以内);普通真空断路器的合闸涌流高达4.5倍额定电流,而相控断路器的合闸涌流均在2.4倍额定电流以下;控制分闸技术能够保证首开相的工频续流开断时断路器断口间有足够的开距,降低重燃发生的概率,从而提高系统运行的安全性与可靠性。

Phase-controlled vacuum circuit breaker（VCB） is one of the important measures to suppress inrush current and transient overvoltage in the process of switching shunt capacitor banks. In order to verify the effectiveness of the technique, the impact of closing angle on the inrush current based on the circuit theory and opening overvoltage mechanism are analyzed first. Then a series of field experiments are carried out using a type of phase-controlled VCB and regular VCB switching shunt capacitor banks at an 110 kV substation in Chongqing. Field experimental results show that the precision of controlling the phase-controlled VCB is high（the error of switching on and off is within the range of ±0.3 ms）. Inrush current caused by regular VCB is 4.5 times more than the rated current, while the inrush current caused by the phase-controlled VCB is 2.4 times lower than the rated current. Adequate distance of the contact in circuit breaker when the power-flow current breaking off the first-pole-to-clear occurs is ensured, thus the probability of the restrike is reduced, then the safety and reliability of the power system are enhanced with the phase-controlled technology.