Superconducting Fault Current Limiter Application for Induction Motor Starting Current Reduction

Superconducting fault current limiters (SFCLs) have significant advantages compared with conventional methods of fault current limiting and therefore have been applied to transmission and distribution systems in recent decades. Besides limiting fault currents, SFCLs can also be used to reduce induction motor starting currents. The major purposes for reducing motor starting currents are to alleviate power system voltage sags and to decrease motor winding heating. Traditionally, induction motor starting currents are decreased by applying reduced voltages using autotransformers, wye-delta starters, or series reactors. However, to ensure motor performance in steady-state operation, a step-by-step control scheme needs to be carefully implemented to disconnect the auxiliary devices from the circuit once the startup transient dies out. These approaches are not useful for reducing inrush currents when the circuit is reenergized upon reclosing after clearing a fault on a neighboring feeder. In this paper, we propose a scheme to reduce induction motor starting currents using SFCL, which has a less complex structure and provides more implementation flexibility than traditional methods. A detailed simulation model of the system with a power source, SFCL, induction motor, and a load is established in MATLAB-Simulink. The results demonstrate the validity and effectiveness of the proposed scheme.