Application Studies on the Active SISFCL in Electric Transmission System and Its Impact on Line Distance Protection

The application of superconducting fault current limiters in transmission systems is very attractive because the devices offer superior technical performance in comparison to conventional methods to limit fault currents. The superconducting fault current limiters show high impedance during fault period and negligible impedance in the circuit during normal operating conditions. This paper illustrates the operation performance of the active saturated iron-core superconductive fault current limiter (SISFCL) and its current-limiting effect on a transmission system. Moreover, investigations are carried out to explore the impact of the active SISFCL on the distance protection of the transmission line. Novel principle and application solutions are first proposed to eliminate the adverse effects that the active SISFCL has on the distance relay protection. A 500-kV double-circuit transmission system with active SISFCLs is simulated by using the Electromagnetic Transients Program including DC software package. Results from simulation tests have demonstrated the correctness and validity of theoretical analyses.