一起主变压器低压侧故障的分析与对策

内桥接线是110kV变电站广泛采用的电气主接线方式,介绍了一起内桥接线的110kV变电站主变压器低压侧故障相关保护的动作过程。该故障为主变压器低压侧断路器因触指长期过热失去弹性,触头脱落造成相间短路,因主变压器高后备保护拒动,上级220kV变电站线路保护动作并重合,备自投不合理动作,备用线路投入,故障点多次冲击,造成低压断路器烧毁,全站失电。此故障具有一定的典型性,说明典型设计中保护配置存在一定问题。文中对这起故障的保护动作行为进行了全面分析,对如何合理配置保护,避免相同类型故障的发生,提出了建议与对策,对内桥接线变电站的保护配置与整定、运行与维护有参考意义。

Analysis and Countermeasure of a Circuit Breaker Fault at Low Voltage Side of a Main Transformer

Inner-bridge configuration is a kind of main electrical connection widely used in 110 kV substations. This paper describes the protection action process during a circuit breaker fault on the low voltage side of the main transformer in a 110 kV substation with inner-bridge configuration. The long-term overheat made the button contact of the low voltage side circuit breaker of the transformer lose its elasticity. The contact fall off caused an interphase short circuit. Since the high voltage side back-up protection of the transformer failed to operate, the line protection and recloser of the superior 220 kV substation acted. And automatic switchover acted irrationally while the backup line put in. The circuit breaker was damaged by the rush more than once until the substation lost power. The fault is to a certain extent typical of a power system with problems in the design of its protection configuration. An overall analysis is made by the authors on the protection action process of the fault alongside suggestions and countermeasures for optimizing main protection configuration and setting, as well as operation and maintenance of inner-bridge configuration.