전력계통용 자속구속형 초전도 한류기의 특성연구

Abstract

We investigated the quench characteristics of a flux-lock type superconducting fault current limiter (SFCL) according to the number of the serial connection between the superconducting elements at the subtractive polarity winding of a transformer. The flux-lock type SFCL consists of two coils. The primary coil is wound in parallel to the secondary coil through an iron core, and the secondary coil is connected to the superconducting elements in series. The operation of the flux-lock type SFCL can be divided into the subtractive and the additive polarity windings according to the winding directions between the primary and secondary coils. In this paper, we investigated the current limiting characteristics of the flux-lock type SFCL. The fault current of the flux-lock type SFCL with the additive polarity winding during first-half cycle after the fault was limited effectively more than that of the subtractive polarity winding. The quench time of the flux-lock type SFCL in the additive polarity winding was also quicker than that of the subtractive polarity winding. Therefore, we confirmed that the value of limited fault current during the initial fault reduced in the additive polarity winding. The fault current was limited faster with the increase of fault angle in both the subtractive and additive polarity windings because the quench time of superconducting elements shortened. In addition, the fault current in the additive polarity winding was effectively limited with the inductance increase of secondary winding when it was compared to the subtractive polarity winding under the same condition. The analyses of voltage, current, and resistance in serial connection between superconducting elements were performed to increase the voltage rating of the flux-lock type SFCL. The power burden was reduced through the simultaneous quenching between the superconducting elements. This enabled the flux-lock type SFCL to be easy to increase the capacity of power system.