Fault analysis of VSC-HVDC system with saturated iron-core superconductive fault current limiter

VSC-HVDC is one of the important development directions in smart grid. However, VSCs are vulnerable to dc-cable short-circuit faults due to the high discharge current from the dc-link capacitance. The huge current is a great threat to the capacitors and diodes. In order to limit the fault current to a relatively low level, the superconductive fault current limiter is introduced into the VSC-HVDC network and becomes an effective solution. The cardinal principle and electrical properties of SFCL are presented first. The transient process of the inter-pole short circuit fault in VSC-HVDC network with SFCL is analyzed. The effectiveness of SFCL is demonstrated through the comparison of fault current and voltage on network with and without SFCL. The correctness of the theoretical analysis is testified by simulation results in PSCAD/EMTDC.