Study on Protective Coordination for Application of Superconducting Fault Current Limiter

In this paper, the effects on the protective coordination of a superconducting fault current limiter (SFCL) with the protective devices were analyzed. The SFCL has been noticed as the best solution to limit fault current effectively, which has continuously increased due to the expansion of the power facilities for the increased power demand. However, the application of the SFCL in the power system affects the protective coordination of the existing protective devices and can deviate their operation time from the original one. Therefore, the studies on the protective coordination considering the introduction of the SFCL are necessary prier to its installation. In this paper, the method to keep the protective coordination of the protective devices with the SFCL, which have been installed and tested in the Korea Electric Power Corporation (KEPCO) power test field, was investigated through the various case studies considering the load capacities and the impedance of the SFCL. Among the setting parameters of the protective device to meet the guideline required in the power distribution system, the time dial (TD) values of the protective device required for the protective coordination according to the load capacities and the impedance of the SFCL were derived. Through the analysis on the derived results, the lower TD value could be confirmed to be needed in the case of both the higher load capacity and the SFCL with its higher impedance.