Study of a Modified Flux-Coupling-Type Superconducting Fault Current Limiter for Mitigating the Effect of DC Short Circuit in a VSC-HVDC System

In view of the development of high-temperature superconducting materials, more applications on electric utility devices are used in the power industry. In this paper, a modified flux-coupling-type superconducting fault current limiter (SFCL) is suggested to mitigate the effect of DC short circuit in a voltage source converter-based high-voltage direct current (VSC-HVDC) system. The SFCL's structural principle is firstly presented. Then, considering that the SFCL is placed in series with a VSC-HVDC transmission line, its influence mechanism to the DC fault current's dynamic process is analyzed, and some brief discussions on the design of the SFCL are carried out. Further, the detailed model of a 100-kV-class VSC-HVDC system integrated with the SFCL is built in MATLAB/SIMULINK, and a simulation analysis is performed. From the demonstrated results, applying the SFCL can help to suppress the DC fault current, compensate the DC voltage sag, and maintain the power balance. Consequently, the VSC-HVDC system's robustness against the DC short circuit fault can be well enhanced.