Parameter optimization of SFCL with wind-turbine generation system based on its protective coordination

This paper describes a study to determine the optimal resistance of a superconducting fault current limiter (SFCL) connected to a wind-turbine generation system (WTGS) in series considering its protective coordination. The connection of the WTGS to the electric power grid may have serious effects on the stability and reliability of the overall system during a contingency due to the increase in fault currents. Moreover, it causes malfunction in the protective devices such as overcurrent relays (OCRs). To deal with this problem, the SFCL is applied to reduce the level of fault current increased by the connection of the WTGS. Then, to determine the optimal parameter of the SFCL, protective coordination between the existing multiple OCRs is considered based on the computation of fault current by the equivalent voltage source method. The effectiveness of the optimal resistance for the SFCL is evaluated by the time-domain simulation with the power systems computer aided design/electromagnetic transients including DC (PSCAD/EMTDC) software. The results show that protective coordination is well maintained without changing the previous settings of existing OCRs by applying the SFCL with its optimal parameter. Therefore, the system can keep its suitable reliability even when the level of fault current is increased by connecting the WTGS to the power system.