With the rapid development of ultra high voltage direct current(UHVDC)project

the excessive fault removal time at the receiving end of the AC system will lead to continuous commutation failure of UHVDC. The resulting large power shocks will put the stable operation of the system at risk. Based on the traditional protection criteria

the fault removal time of AC system circuit breaker failure and dead zone(CBF & DZ)might be over 400 ms

which could no longer meet the stability requirements of modern power grid. On the basis of a brief description of the failure protection logic used in CBF & DZ and their deficiencies

the engineering application technology scheme of CBF & DZ protection for 3/2 breaker connection is proposed

and the strategy of shortening the CBF & DZ removal time on the basis of substation area information is introduced. To be more specific

firstly

using the set of conditions formed by the integrated protection fault information

a fast and accurate location of the fault breakers is realized. Secondly

harnessing switch current comparison and adaptive adjustment of no current setting are used to reduce the influence of current transformer trailing current on the protection criterion. Thirdly

by constructing dedicated optical fiber channel and split phase tripping method

the communication delay is reduced and the reinitiated tripping stage is reduced. The proposed protection strategy is verified through real time digital simulator(RTDS)test and the potential risks are analyzed as well.