Reduction of the Power Burden of a Transformer-Type SFCL Using a Vacuum Interrupter

Various protective equipment have been used to enhance the supply reliability and transient stability of a power system. A superconducting fault current limiter (SFCL) is electric power equipment that reduces the fault current in a power system. In the power system in Korea, an SFCL that can consistently restrict fault currents for 1.5 s or longer without support from a stable current limiting operation, a reclosing operation, and a circuit breaker was required. In this study, we suggested methods of improving the performance of a transformer-type SFCL. The superconductor in the secondary winding of a transformer-type SFCL was connected to a vacuum interrupter in series. As a result, the current limiting performance was enhanced, and the burden of the superconductor was decreased significantly. The superconductor restricted only the initial fault currents, and thereafter, the limiting operation was conducted by reactor of the transformer, which significantly improved the duration time of the current limiting operation. These outcomes satisfy the SFCL conditions required by the power system, so practical applications may be possible.