The two-level voltage source converter(VSC)has a high cost-efficiency ratio in the electric transmission occasion of 35 kV and below voltage level
so it is widely used in the low voltage area such as wind power integration. However
its incapability of DC fault clearing brings the great challenge to the operation of grid facilities. Based on the above background
this paper proposes an assistant topology with DC fault clearing capability applied for two-level VSC. The DC fault current is drastically reduced by the assistant topology using the superconducting fault current limiter(SFCL). Based on the current resonance method
the fault is cleared when the fault current oscillates to zero. When employing the proposed topology
the DC fault clearing time is shorter and the fault current is lower compared with the fault clear scheme employing AC circuit breaker. In addition
it has the advantages of smaller voltage change rate and more cost saving in engineering compared with the scheme employing DC circuit breaker. Finally
the correctness and effectiveness of the proposed topology is verified in PSCAD/EMTDC.