To reduce the more increased fault current due to the increase of the power generation with the power demand, the superconducting fault current limiter (SFCL) has received attention as one of the effective methods to resolve the fault current problem. However, the operation of the protection device, especially dependent on the amplitude of the fault current, can be affected by the application of the SFCL. For the protection coordination between the SFCL and the over-current relay (OCR), one of the typical protection devices in the power distribution system, the resetting of operational parameters in the OCRs, which can be troublesome, is required. For these resettings of the protection devices, the fault current calculation from the power distribution system considering the impedance of the SFCL is inevitable. In this paper, the method using the voltage component as the effective parameter of the OCR for the protection of the power distribution system with the SFCL was suggested. Through the analysis on the simulation results from the modeling of the OCR, the suggested method using the voltage component in the OCR could be confirmed to be more effective compared to the previous resetting method of the OCR.

The current limiting and recovery characteristics of a trigger type superconducting fault current limiter (SFCL) using double quench, which consists of a power switch, two separated current limiting resistances and two superconducting (SC1, SC2) elements, were analyzed. The suggested trigger type SFCL can perform two fault current limiting operations (single quench operation and double quench operation) according to the amplitude of the initial fault current. In case of lower amplitude of the initial fault current, the fault current limiting operation of the SFCL can be performed through the occurrence of the single quench in SC1 element connected in series with the power switch. In case of larger amplitude of the initial fault current, the second quench in SC2 element connected in parallel with one of the separated current limiting resistances after the first quench in SC1 element occurs, namely, double quench, is contributed to the larger fault current limiting operation of the SFCL.