The Optimization Of Action Delay For 220kV Circuit Breaker Failure Protection

The requirement of the power gird to the fault clearing time is getting higher,the influence of the breaker failure to the stability of power system is becoming larger,the action delay of 220 k V circuit breaker failure protection is important for the stable operation of the power grid.On the premise of selectivity and completeness,the acting time of the circuit breaker failure protection ought to be as far as possible to shorten.Domestic 220 k V power grid system is given priority to double bus connection,the circuit breaker failure protection acts on the bus tie breaker and section breaker in a short time delay,which acts on all the breakers connected to the fault bus.In the previous applications,the scheme can guarantee the time coordination of the breaker failure protection and other protections.But with the development of power grid scale and the complexity of the composition,the scheme is difficult to satisfy the stability of power system.When some 220 k V line failure occurs and the breaker fail to operate,the system is still unable to maintain stability even though the circuit breaker failure protection acts correctly.In order to solve above problem,our research aims to shorten the action delay of the breaker failure protection,the similarities and differences of different types of protections failure criteria such as transformers,lines and bus couplings,as well as the cooperation between the failure protection,follow-up protection and dead-zone protection are systemically studied,the main factors deciding the time delay of the breaker failure such as protection operating time,breaker breaking time,breaker quenching time and current components return time,and the distribution characteristics of the various factors are deeply analyzed.Consequently,the theoretical minimum of the breaker failure protection’s time delay are obtained.And the theoretical minimum and system stability requirement for fault clearing time are analyzed comprehensively,in the meantime,the possible risk of shortening the delay time of failure protection is revealed and relevant control measures are formulated,then an optimization scheme of breaker failure protection’s time delay are drawn up.Our research achievement can shorten the delay time of failure protection on the premise that the protection does not malfunction,thus isolating fault quickly,ensure the stable operation of the power grid.