一起主变、母差保护相继动作原因分析

Analysis of successive trips of transformer differential relay and bus differential relay

针对一起变电站的110 kV母差保护和220 kV主变保护相继动作跳闸事件展开了分析,通过事故调查发现其存在2个实际故障点,分别位于110 kV母差保护动作区,以及110 kV母差和220 kV主变保护动作的重叠区。当第1次故障发生时,110 kV母差保护动作跳开101断路器;第2次故障导致主变A柜差动保护动作,B柜110 kV复合电压过流保护动作,跳开主变三侧断路器。从继电保护设计的角度出发,对提高继电保护动作可靠性提出了建议。

A substation successive trip event of 110 kV bus differential relay and 220 kV transformer differential relay is described in detail.Investigation shows that two fault points are located respectively in the 110 kV bus relay operation zone and the overlap operation zone of bus relay and transformer relay.For the first fault,the 110 kV bus relay trips breaker 101;for the second fault,both the differential relay A and the 110 kV over-current relay B of main transformer operate to trip the transformer breakers at three sides.Suggestions are proposed to improve the reliability of relay operation.