Study of single dc device type FCL for three-phase power system

Various types of fault current limiters (FCLs) that use superconducting element are proposed and are under development, but there are many technical issues: their cost, fault current limiting ability, etc., so at present are far from commercialization. The purpose of this work is to study single dc device type FCL for three-phase power system. The device uses single high temperature superconducting coil that is operated in the diode bridge connected to transformer's secondary windings. The bias power supply is required in the bridge for a rectification type limiter to avoid the distortion of load currents. This bias power supply requires the ability to supply at least the load currents in the steady state in the power system. Also the ability that many times of rated line currents can flow in the bias power supply at the time of a fault is required. In this paper, we study technical items that are demanded on this bias power supply and provide the optimal constitution of simple dc device type FCL for three-phase power system.