HIGH-TEMPERATURE SUPERCONDUCTING DC NETWORKS

High-temperature superconducting dc networks are studied as a feasible alternative to ac power transmission systems. The dc network operates at generation voltages allowing direct connection of the generators to the rectifiers, eliminating the need for high-voltage insulation and transformers. The dc system is based on a mesh connected few-voltage high-current superconducting dc transmission network supplied by unit-connected generators. The dc system feeds many small inverters that pass controlled levels of real and reactive power to ac loads. This paper presents an overview of superconducting low-voltage dc transmission systems, starting with a discussion of the dc system. This discussion is followed by an overview of the operation of ac distribution systems connected to the superconducting dc mesh and then inverter topologies and control strategies required for interfacing the ac distribution systems to the de mesh. The paper presents a conceptual overview of the operation of the system based on simulation studies.