To reduce the peak value of fault current of DC power grid

we introduced a high voltage DC circuit breaker that could break short fault without arc

and analyzed the principle of arrester and fast mechanical switch. Then

we proposed a new breaking method to solve the problem of relatively long duration of fast mechanical switch breaking. The arrestors that immediately operate mechanical switch can meet the demands of voltage withstanding capacity; the method reduces the peak value of fault current and stress endured by key equipment in system

besides the energy absorbed by arrestors is lowered and thermal effect caused by impulse current is minimized. Finally

the simulation results in PSCAD/EMTDC show that the proposed breaking method is effective.