Design guideline of flux-lock type HTS fault current limiter for power system application

The authors have proposed a “flux-lock” type high T _c superconducting (HTS) fault current limiter (FCL) composed of a flux-lock reactor with HTS element and a magnetic field coil circuit. In this FCL, the initial limiting current level can be arranged by setting the inductance combination of the flux-lock coils and an AC magnetic field is applied to the HTS to get higher resistance only in a current limiting phase. This paper describes design guidelines for the NTS-FCLs. The impedances of the FCLs were expressed as a function of the product of the normal resistance and the square of the quench current level, which the authors have proposed to refer to as “quench power”. Supposing the FCLs are introduced into the extra-high voltage transmission system and power distribution system, the “quench power” necessary for the FCLs to suppress the fault current under the required level was discussed