Flux-coupling fault current limiter design for VSC DC grids.

DC circuit breakers (DCCBs) are used to clear short-circuit faults in several milliseconds. However, short-circuit fault current can reach extreme values. Fault current limiters (FCLs) can present high inductance values during the short-circuit fault period. Thus, they have received considerable attention for reducing the high current breaking requirements of DCCBs. Three types of magnetic flux-coupling solid-state FCLs are designed in this paper, which include mutual inductors and several power electronic switches. In addition, the FCL impedance can be controlled by power electronic switches. By comparing the current limit capacities and structural complexities among the three types of FCLs, a more applicable limiter referred to as a flux-coupling DC current limiter (FCDCCL) can be installed on VSC DC grids. Finally, a simulation model is built in PSCAD/EMTDC based on a ± 10 kV/400 A DC system. The simulation results verify that a significant change in the limiting current can be achieved by the proposed FCDCCL, which can be extended to actual VSC DC grids. [ABSTRACT FROM AUTHOR]