DC Loop Type Superconducting Distribution System Including Various Distributed Generations

A dc loop type distribution system using an HTS cable is proposed as one of promising future power systems with many distributed generations. Applying the HTS dc cable can overcome the drawback to normal conducting medium-voltage large-current systems, which is large power loss in the cables, as well as the drawback to ac systems, which is the ac loss in superconducting cables. It also has a possibility to realize good power sharing among power sources in the systems. In this paper, the advantages of the proposed system are discussed and the protecting operation of the system using superconducting fault current limiters is also investigated by numerical circuit simulation. Moreover, power sharing control between the rectifiers, which employ constant voltage control with the gain-scheduling technique, is demonstrated by the experiments using a small-scale normal conducting circuit.