火电厂低压厂用电接地保护配置方案研究

Research on Configuration Scheme of Low-voltage Auxiliary Power Grounding Protection in Thermal Power Plant

文章通过对低压厂用电接地保护配置实例进行计算,分析了目前断路器智能脱扣器、熔断器和塑壳断路器在系统发生单相接地时配合困难的原因,提出了保护配置方法,解决了因本回路保护拒动,上级PC馈线零序保护越级跳闸,导致大面积失电问题以及由于相间短路保护灵敏度不够,自身保护无法动作,上一级保护也无法跳闸,最终电缆线路全部烧毁的问题。

In This paper,an example of low-voltage auxiliary power grounding protection configuration is calculated,and the reason of the coordination difficulty of the current circuit breaker intelligent release,fuse and molded case circuit breaker when single-phase grounding occurs in the system is analyzed.The protection configuration method is proposed,which solves the problems of circuit protection rejection and superior PC feeder zero-sequence protection override trip.As a result,a large area of power loss is caused,and due to insufficient sensitivity of interphase short circuit protection,its own protection can not act,the upper level of protection can not trip,and finally all cable lines are burned down.