Impact Of The High Temperature Superconducting Fault Current Limiter On The Protection For The Extra High Voltage Transmission Line

An increasing number of power generations are installed in the power system to satisfy the rapidly growing demands for large power load. As a result, the increasing high fault current level in the grid is going above the capacity of the existing power equipment, such as circuit breakers, which may threaten the reliability and security of the power system. Under the circumstances, two methods are usually adopted by the grid company to cope with the problemSuperconducting fault current limiter(SFCL) techniques are gaining more and more popularity than conventional fault current limiting methods, because the devices can limit fault current during fault period without presenting high impedance in the circuit during normal operating conditions. Up to now, the SFCL has experienced a rapid development and the most important types of the SFCL contain the dc biased iron-core type, the resistive type, the bridge type and so on. The resistive type has been introduced in..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.The paper illustrates the operation performance of the active saturated iron-core superconductive fault current limiter(SFCL) and its current-limiting effect on a transmission system. Besides, 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 Electro-Magnetic Transients Program including DC(EMTDC) software package. Results from simulation tests have demonstrated the correctness and validity of theoretical analyses.