Design and Experimental Characterization of HTS-Tape Solenoidal Magnetic Screens for the Design of IR-SFCL Magnetic Structure

The continuous evolution of electrical distribution systems—driven by the integration of renewable energy sources and decentralized generation—poses new challenges for grid protection. Superconducting Fault Current Limiters (SFCLs) have emerged as efficient, low-impact solutions capable of limiting fault currents without interfering with normal system operation. Among these, the Inductive-Resistive (IR-SFCL) architecture offers notable advantages in robustness and adaptability. However, previous prototypes developed by the research group revealed two critical limitations: the low contribution of the resistive stage in fault current limitation, and the fragility of the superconducting magnetic shields used in the inductive stage, traditionally made of rigid and costly bulk high-temperature superconductors (HTS) materials. This work presents a redesigned IR-SFCL that addresses both issues. The resistive stage has been optimized by increasing the active length of HTS tape exposed to the magnetic field, enabled by a new ferromagnetic core design. In parallel, the inductive stage incorporates novel solenoidal magnetic shields built from commercial HTS tape, offering improved mechanical flexibility and enhanced performance under thermal cycling. Experimental shielding tests were conducted to validate the proposed approach and to extract key parameters for device design. Results confirm the effectiveness and reliability of the new solenoidal shields and introduce a new design variable: the number of HTS tape layers, which directly influences the current-limiting capacity of the IR-SFCL.