Combined Effect of the SFCL and Solenoid Coils

As the capacity of power facilities increases with the power demand, the fault current also increases in the case of a power system fault. Many studies are underway to limit the increasing fault current. They especially include superconducting fault current limiters (SFCLs). The existing SFCLs operate almost without loss because of their zero resistance characteristic in the normal condition, but limit the fault current by generating impedance in the event of a fault. However, this mechanism gives a significant burden on the SFCL. In this study, a high-speed interrupter and a normal conduction current-limiting unit were applied to the SFCL. In this structure, the current flows through the b-switch of a high-speed interrupter and the current-limiting element in the normal condition, but in the event of a fault, the current was bypassed to the current-limiting unit by the quench of superconducting units and interrupter switching operations. In this case, the magnitude of the fault current was covered by the SFCL, and after the switching operation, the current was limited by the normal conduction current-limiting unit. The results of this study showed that this structure reduced the power burden on the expensive superconducting element, and limited a high fault current that was initially generated from the fault.