两点接地导致500kV保护误动分析及控制

Analysis and control of 500kV protection maloperation caused by two points grounding

目前电网发生多起高压变电站电流互感器二次回路误碰两点接地导致500kV保护误动的事故,因为500kV保护采集的是两台电流互感器二次回路的和电流,采取二分之三接线方式,当其中一台电流互感器及其二次回路检修停运,另外一台电流互感器及其二次回路仍然运行,此时如果在工作中对风险控制措施不妥将会导致保护误动作,导致电网事故。本文在通过案例分析总结出高压变电站500kV保护采集的是两台电流互感器二次回路的和电流接线方式情况在维护中风险控制措施,遵循"先断后短"的安全措施原则进行控制,同时也总结一般220kV保护常规双母线接线方式风险控制措施,一般遵循"先短后断"的原则,该原则已在工程中得到实践。

At present, there are many secondary faults in the secondary circuit of the current transformer of the high-voltage substation. The two-point grounding of the current transformer causes a 500 kV protection misoperation because 500 kV protection collects the currents of the secondary loops of the two current transformers and adopts two-fold. In the three-connection mode,when one of the current transformers and its secondary circuit is overhauled and stopped, another current transformer and its secondary circuit are still running. At this time, if the risk control measures are improper in the work, it will accidents. This article summarizes the 500 kV protection of high-voltage substations through the case analysis and summarizes the rislcontrol measures in the maintenance of the secondary circuits of the two current transforin the project practica.