一起失灵保护误动分析及启示

Analysis and Enlightenment for a Mal-Operation of Break Failure Protection

断路器失灵保护作为电网和主设备重要的近后备保护,是继电保护中很重要的保护。其基本原理为继电保护动作发出跳闸命令而断路器拒动时,利用故障设备的保护动作信息与拒动断路器的电流信息构成对断路器失灵的判别,能够以较短的时限切除同一厂站内其他有关的断路器,将停电范围限制在最小,从而保证整个电网的稳定运行,避免造成发电机和变压器等故障元件的严重烧损和电网的崩溃瓦解事故。失灵保护动作后将切除跟拒动断路器有直接电气连接的所有支路,涉及跳闸范围广,对系统影响大,故其保护逻辑和二次回路的设计准确性显得十分重要。通过深入分析一起失灵保护误动案例,找出误动的原因,并提出相关的设计改进措施。

Breaker failure protection is an important local backup protection for the power grid and main equipment,and is an important protection in relay protection.The basic principle is that when the relay protection issues a trip command and the circuit breaker is failure to operate,the protection action information of the faulty equipment and the current information of the refused circuit breaker constitute the judgment of the failure of the circuit breaker,cutting off other related circuit breakers in short time in the plant and station,so as to limit the scope of power outage to a minimum and ensure the stable operation of the entire power grid,and avoid causing serious damage to generators,transformers and other faulty components and the collapse of the power grid.After the break failure protection acts,all bays which directly connected to the failure circuit breaker will be cut off,which involves a wide range of tripping and has a great impact on the system.Therefore,the design accuracy of protection logic and secondary circuit is very important.In this paper,through an in-depth analysis of a case of breaker failure protection mal-operation,find out the cause of maloperation,and propose related design improvement measures.