The VSC-HVDC power grid faces a great challenge of rapidly isolating DC fault. DC circuit breaker is an effective solution for DC fault isolation. In view of the existing difficulties of the DC circuit breaker

such as low isolation speed of short-circuit fault

high-level injection of short-circuit current by converter station side

we proposed a novel topology of HVDC circuit breaker

which uses capacitor commutated branches to create reliable and fast breaking conditions for this topology. The topology can quickly isolate DC short-circuit fault

limit the level of short-circuit current effectively

and reduce the impact of short-circuit fault on converter valves. Moreover

we described the structure and working principle of the topology

and analyzed the breaking process theoretically. Meanwhile

we analyzed the influences of two different interrupting strategies on parameters design. Finally

the topology is modeled in MATLAB/Simulink

the simulation results verify the effectiveness of the proposed topology on isolating DC fault.