Reliability Enhancement of the Fast Switch in a Hybrid Superconducting Fault Current Limiter by Using Power Electronic Switches

We have investigated reliability enhancement of the fast switch (FS) by using power electronic switches such as integrated gate commutated thyristors (IGCT) in the line commutation type hybrid superconducting fault current limiter (SFCL). The FS utilizes a vacuum interrupter (VI) to open and close the primary power line. The operation of the FS highly relies upon the complete line breaking by the VI. Since the primary line resistance including the arc resistance may not be extremely high after the VI opens, there may be non-zero arc current in the VI, causing a failure in the line communication. The IGCTs are to completely remove the remanent current in the VI, guaranteeing the arc extinction and enhancing reliability in operation. We fabricated and successfully tested the SFCL which was equipped with the IGCT-assisted FS.