| Superconducting fault current limiters offer superior technical performance in comparison with conventional methods to limit fault currents. Due to prominent advantages and practical demand, the saturated iron-core superconductive fault current limiter(SISFCL) has been applied on transmission lines and distribution system.Considering the actual structure, the sophisticated equivalent magnetic circuit of the SISFCL was proposed first. The electromagnetic transient simulation model of the SISFCL was built in Matlab/Simulink. In order to realize accurate electromagnetic transient simulation, Newton iteration method and fundamental magnetic magnetization curve are introduced into the calculation of the current-limiting inductance during simulation. The transient behavior of the SISFCL in simulation tests illustrated that the proposed method is valid and correct.The active Saturated Iron-core Superconducting Fault Current Limiter(SISFCL) is one of the best solutions to coping with high fault current levels and may be helpful in building future smart distribution networks. The influence of an active SISFCL is discussed in detail for the conventional inverse time-delay overcurrent protective relays. In order to maintain reliable operation of the distribution system with an SISFCL, the protection coordination and setting solution is proposed. A model of a real 35 kV distribution system with an active SISFCL was built and simulated with the Electro-Magnetic Transients Program including DC(EMTDC) software.The influence of an SISFCL on the zero-sequence current protection of the grid, taking into consideration both the fault of SISFCL itself and fault of the power lines, is discussed. In order to coordinate the SISFCL and the grid protection scheme, requirements and recommendations are proposed. A model of a 500 kV double-circuit transmission system with SISFCLs is built. The simulation results are in good agreement with the theoretical analyses. |
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