Control System Modeling and Simulation of Superconducting Current Limiter With Saturated Iron Core Controlled by DC Bias Current

This paper presents a basic structure of superconducting fault current limiter (SFCL) with saturated iron core. A mathematical model of this SFCL is established after analyzing its physical principle. Simulation results show that if the dc bias current is cut off, the SFCL with saturated iron core can limit the short-circuit fault current quickly and effectively. A control system model with input of dc bias current and ac supply voltage, output of ac impedance of SFCL is presented. Simulations show that the ac impedance of SFCL can be effectively controlled by controlling the dc bias current. The smaller the dc bias current is, the bigger the impedance of SFCL is in the scope from saturated state to non-saturated state. In deep saturated state, the impedance of SFCL changes little following the change of dc bias current. The relation between them is nonlinear.