Research On Override Tripping Of DC System Of Twelve Substations In Tianjin

Power system has been gradually developing into stages of high voltage and large capacity.Due to the complication of the structure and heaviness of the workload,DC system,as the control and protection of power substation,usually takes three to four level circuit breaker or fuse series.However,choices of protection equipments and cooperation of different levels appear to face series of problems.This paper analyzes the calculation of the short-circuit current of DC system and the cooperation of differential protection.In addition,the simulation model of DC power supply system is created,based on 12 substations in Tianjin,which tested the mutual cooperation of different types of DC circuit breakers,DC circuit breakers,fuses,DC circuit breakers and AC circuit breakers.As well,alongside the analyzation of function of DC breaker,the weakness of the usage of AC breakers alone or the cooperation of AC breakers and DC breakers has been discussed.In the end,in order to prevent the protection override,we proposed a combination of anti operation over voltage suppression measures and a designing principle of DC circuit breaker selection.