Development and Grid Operation of Superconducting Fault Current Limiters in KEPCO

Development and grid operation of superconducting fault current limiters (SFCLs) have been carried out in Korea Electric Power Corporation (KEPCO), as a possible measure to handle the increasing fault current in Korea. A 22.9 kV SFCL has been successfully operated unmanned on a distribution line of Icheon Substation. It has been very stable throughout the operation of more than 1.5 year. Temperatures and level of liquid nitrogen that cools the superconducting element have been maintained constant. Performance of the SFCL maintained the initial level. The SFCL was modified so that it can limit the fault current within the first half cycle. A short-circuit test on the modified SFCL showed it started limiting the current within 2 ms. In parallel, a 154 kV SFCL has been also developed. A superconducting element was designed and fabricated. A short-circuit test was performed on a superconducting unit module, and showed that the module limited the current effectively. The element is planned to be integrated into a single-phase 154 kV SFCL together with the cooling system and other components, and tested soon.