一起出线过流保护误动事故分析

Analysis of an accident of a feeder over-current protection malfunction

介绍了2004年如皋变电站检修完35 kV侧出线开关后进行倒闸操作时所发生的过流保护误动事故经过。分析结果表明,对于单母分段带旁路这种接线方式,在由旁路开关代替出线开关运行方式恢复到正常供电方式时所进行的倒闸操作过程中,根据不停电原则,在倒闸操作过程中会形成环网;此时若出线负荷远小于分段母线负荷,则必然出现负荷转供现象,致使流经出线开关的电流远大于正常情况下该出线可能出现的最大负荷电流,造成出线开关过流保护误动。最后,文章就如何预防这类事故提出了有效的解决方案。

This paper introduces a malfunction of over-current protection, which happened in the operation of switching breakers in a 110kV substation of Rugao in 2004. The calculation result shows that, to the interconnection style of sectionalized single bus with transfer bus and according to the principle of no interruption of power supply, there will form a ring net during the operation of switching breakers which changes the way of power supply from using a bypass switch to a feeder switch. When feeder loads are far less than sectionalized bus loads, with the transporting of loads, the current flowing through the feeder switch is larger than the possible maximum load current, and the feeder over-current protection malfunction happened. Efficient solutions are presented in the end.