Operational characteristics of a flux-lock-type high-Tc superconducting fault current limiter with a tap changer

The authors investigate the operational characteristics of a flux-lock-type high-T_c superconducting (HTSC) fault current limiter (SFCL) with a tap changer which could adjust the number of turns of the third winding. In the case of conventional flux-lock-type SFCL, the phase adjusting capacitor is connected in series with magnetic field coil to adjust the magnetic field applied to the HTSC element in phase with the current flowing through the HTSC element during a fault time. However, the current flowing at the third winding, which is connected with magnetic field coil, affects the fault current limiting characteristics. To analyze the influence of current flowing at the third winding on the fault current limiting characteristics, the fault current limiting characteristics of the flux-lock type SFCL, whose inductance of coil 3 could be adjustable through a tap changer, are investigated through the experiments and the computer-aided simulations. The relation of line currents flowing into the flux-lock-type SFCL during a fault time and numbers of turns of a tap changer is drawn.