Current Limiting and Recovery Tests Under Load of Three-Phase Transformer Type Coaxial SFCL in a Model Power System

Superconducting Fault Current Limiters (SFCLs) are expected to be installed in the power system for improving their reliability and stability. The three-phase transformer type coaxial SFCL with rewound structure have been proposed and designed in the past. Due to the rewound structure, internal magnetic field of an SFCL is cancelled and each phase of the SFCL can work independently without interference with the other coaxial phases. This paper describes current limiting performance and recovery characteristics in Recovery Under Load (RUL) operation of the proposed SFCL. The operation tests of the SFCL under load were carried out on a lab-scale model power system (one generator, double-circuit transmission line, and infinite bus system). In this system, faults occurred on one line. The SFCL was installed in the generator terminal in series and the generator continued to supply power to another line through the SFCL in fault sequence so the SFCL operated in RUL. It was confirmed that the SFCL limited the fault current from approximately 600 to 250 A, reduced the burden of the generator, and successfully recovered to superconducting state.