초전도 소자에 의한 DC 차단기의 동작 특성

Abstract

Superconducting current limiting impedance selection method according to the DC circuit breaker operation characteristics for economic gain with the HVDC hybrid type superconducting DC circuit breaker is attracting attention globally. Due to the development and expansion of renewable energy sources and the development of power semiconductors, HVDC has the advantages of high system transmission efficiency and asynchronous connection. HVDC is currently being developed and commercialized as a pole-to-pole system. As the development of MVDC, LVDC and HVDC progresses, DC grid systems capable of exchanging DC power with each other will be built. A circuit breaker that can increase the reliability of the DC system operation should therefore be developed. HVDC, hybrid, semiconductor and reverse-current-type circuit breakers have been studied as potential circuit breaker options, with many papers being published to demonstrate their respective performances. In this paper, a hybrid superconducting DC circuit breaker was proposed. It consists of a superconducting fault current limiter, a mechanical cut-off contact, an LC circuit and a SA(SA). The rapid rise of the fault current was limited by using the impedance of the superconductor, while the fault current was interrupted by the cut-off operation of the mechanical DC circuit breaker. If the superconducting element shows higher fault current than the breaking capacity level of the DC circuit breaker and the burden on the superconductor will increase. Therefore, efforts were made to confirm the appropriate cut-off capacity level of the DC circuit breaker and the current limiting impedance of the superconductor through experiments. As a result, we proved that the current limiting impedance of the superconductor could be analyzed based on the tripping operation of the DC circuit breaker.