Coordinated overcurrent protection in distribution grids incorporating an active superconducting fault current limiter

The active saturated iron-core superconducting fault current limiter (SISFCL) is a promising technology for mitigating excessive fault currents in modern power distribution systems. This device is particularly valuable for integration into evolving smart grids, as it effectively suppresses fault currents during short-circuit events throughout the network. This paper offers a concise explanation of the SISFCL's working principles and its impedance behavior under fault conditions. The impact of integrating such a limiter on conventional inverse and fixed time-delay overcurrent protection schemes is examined. To ensure dependable protection performance in systems using SISFCLs, a method for coordinating protection settings is introduced. A model based on an actual 35 kV power distribution system with an integrated SISFCL was developed and evaluated using EMTDC/PSCAD software. The simulation outcomes confirm the soundness of the analytical framework. Index Terms—Active SFCL, saturated core, power distribution network, overcurrent relay, coordination, inverse-time protection.