Enhancement of Renewable Power System Protection Reliability Using a Superconducting Fault Current Limiting Circuit Breaker (SFCL-CB)

The proliferation of inverter-based resources (IBRs) and energy storage systems in power grids has led to a decline in the short-circuit ratio (SCR) and reduced fault current magnitudes, compromising the reliability of conventional overcurrent relays (OCRs) and creating protection blind zones. To resolve these vulnerabilities, this paper proposes an electromagnetic repulsion-based Superconducting Fault Current-Limiting Circuit Breaker (SFCL-CB) utilizing a flux-lock type mechanism. Unlike protection schemes that rely on secondary accessories such as current and potential transformers which introduce computational delays, the proposed SFCL-CB utilizes a driving force that scales with the square of the current gradient ((di/dt)2). This characteristic allows the device to distinguish low-magnitude fault currents from transient load growths. Through duality-based modeling and parametric simulations in PSCAD/EMTDC, the structural and electrical design configurations—including the coil turns (N1, N2) and the superconducting quench resistance (RSC)—were optimized. The simulation results verify that the proposed SFCL-CB substantially reduces the OCR blind zone, securing fault clearance within a maximum of 0.131 s in the regions cleared under low SCR and high-fault-resistance conditions, while achieving mechanical separation in 0.0048 s under robust power system. This SFCL-CB offers an alternative to enhance the protection reliability and operational stability of distribution power system.