Transient Performance Improvement of Microgrid by a Resistive Superconducting Fault Current Limiter

In this paper, a resistive-type superconducting fault current limiter (SFCL) is suggested to improve the transient performance of a microgrid system during a fault. The microgrid is connected to the main network at the point of common coupling, where the resistive-type SFCL is applied. When a short-circuit fault happens at the connecting line, the SFCL can mitigate the fault current, and its action signal will be sent to the master distributed generation (DG) included in the microgrid. Accordingly, the switching between the master DG's two control patterns can be flexibly performed; furthermore the microgrid system is expected to achieve a smooth transition between its grid-connected and islanded modes. Theoretical analysis and a technical discussion are conducted, and the simulation model of a typical microgrid with the SFCL is built in MATLAB. From the demonstrated results, employing the resistive-type SFCL can effectively limit the transient fault current to a lower level, help guarantee the microgrid system's power balance, and enhance its voltage and frequency stability.