Improvement of Protection Coordination of Protective Devices Through Application of a SFCL in a Power Distribution System With a Dispersed Generation

The introduction of various dispersed generation (DG) in a power distribution system has caused the short-circuit current to increase, which can make the operation of the protective device deviate from its original set value. Especially, the increase of a short-circuit current in a power distribution system due to the increase of the DG is expected to be required for the related power utilities such as the circuit breaker to be replaced with a larger one. Among the countermeasures to solve the short-circuit problem in a power distribution system considering the increase of the DG, the superconducting fault current limiter (SFCL) has been noticed as one of the promising devices. In this paper, the protection coordination of the protective de- vices due to the application of a SFCL in a power distribution system where the DG was introduced into its bus line was analysed. The experimental circuit to simulate the DG and the protective de- vices was designed and realized by using power electronic switches. The short-circuit tests for the power distributed system assembled with the DG, the protective devices and the SFCL were carried out. Through the analysis on the results from the short-circuit tests, the application of the SFCL with its proper resistance amplitude in a power distribution system with the DG could be confirmed to be contributed to the improvement of the protection coordination of the protective devices.