436 / 2022-03-15 21:53:08

Research on Current-Limiting Characteristics of a New Type of Variable Impedance Superconducting Fault Current-Limiting Transformer

Fast switch, variable impedance, superconducting fault current-limiting transformer

With the continuous increase of the load of the power grid, the high short-circuit fault current threaten the reliability of power systems. Superconducting Fault Current-Limiting Transformer (SFCLT) can transform voltage and limit fault current. When a short-circuit occurs, the SFCLT can respond within a few milliseconds to limit the fault current. But currently, the current-limiting impedance of SFCLT is low that cannot suppress the fault current significantly and cannot be adjusted. This paper proposes a variable impedance SFCLT that could provide flexible current-limiting impedance in fault conditions. Changeable impedance is achieved by the Cooperation of fast switches and the superconducting windings. An experimental model is established based on fast switches and superconducting windings. On the basis, the effects of the topology changing and the types of superconducting tapes on the current-limiting impedance are investigated. The results show that the current-limiting impedance of the proposed SFCLT increases by 30% with the fast switch removing superconducting tapes. The superconducting tape with low critical current can achieve greater current-limiting impedance. With the access of fast switches, the topology of SFCLT is variable, which can reduce the short-circuit fault current in different fault condition and improve the stability of power system.