The improved hysteresis characteristics of flux-lock type SFCL using third winding

Abstract

In this paper, we showed that the third winding of the flux-lock type high- T c superconducting fault current limiter (HTSC-FCL) could be operated as the damping coil to suppress the saturation of the iron core during a fault period. This third winding of the HTSC-FCL was installed to apply the magnetic field into HTSC element simultaneously after a fault happened. To confirm it, the hysteresis characteristics of an iron core of the flux-lock type HTSC-FCL were investigated from the equivalent circuit of a saturable transformer including the nonlinear magnetizing characteristic. Due to the magnetic coupled structure of the flux-lock reactor together with the third winding, the iron core of the flux-lock type HTSC-FCL could be restrained from saturation during a fault period. Through the analysis for the fault current limiting characteristics and the hysteresis ones obtained from the experimental results, the fault current limiting level as well as the saturation of the iron core of the flux-lock type HTSC-FCL with the third winding could be more improved than that of the flux-lock type HTSC-FCL without the third winding.