1000kV系统用并联电容器组不平衡保护设计

Study on Unbalance Protection Design of Shunt Capacitor Bank in 1000 kV System

由于特高压系统110kV侧用并联电容器装置的容量大、电压等级高,其保护设计也出现了一些新问题。为了保障特高压系统安全运行,提高并联电容器装置保护的可靠性,根据电容器组的不平衡保护整定原则,以EMTP软件为计算工具,计算分析了特高压示范工程中并联电容器组多种接线方式下的保护的灵敏度和整定值之间的差异及电容器组的接线方式对耐爆性能的影响。计算得出了故障时电容器元件过电压与不平衡保护电流的关系曲线和保护整定值的合理范围,结果表明:双桥差保护的灵敏度远高于单桥差,目前特高压系统用的并联电容器不平衡保护整定值设置成5个元件发生击穿时跳闸是合适的,这些可为今后设计计算提供参考。

Some new problems have appeared in the protection design of shunt capacitor installations because of their high voltage and large capacity in UHV system. In order to ensure the security of UHV system, it＇s essential to improve the protecting dependability of the shunt capacitor installation. At first, the setting principle of the unbalance protection of the shunt capacitor bank has been explained in this article. Then according to the protection principle, detailed analysis and calculation to the protection setting of the shunt capacitor bank in UHV demonstration project with EMTP, and the impact on the blast resistance performance of the wiring mode of capacitor shunt. In this article, the reasonable protection setting range and the relationship between the over-voltage of capacitor elements and unbalance protection current when capacitor faults have been worked out. The conclusion can be drawn that the protection sensitivity of double-bridge is much higher than the one of single-bridge, and it＇s reasonable that tripping when there are five capacitor elements broke down. All of these offer reference for the future design and calculation.