Feasibility of electric power transmission by DC superconducting cables

The electrical characteristics of dc superconducting cables of two power ratings were studied: 3 GW and 500 MW. Two designs were considered for each of the two power ratings. In the first design, the SUPPLY stream of the cryogen is surrounded by the high-voltage high-temperature superconductor cylinder. The RETURN stream of the cryogen is on the grounded side of the system. In the second design, both the SUPPLY and the RETURN streams of the cryogen are on the grounded side of the cable. Two electrical characteristics of these cables were studied: 1) fault currents and 2) current harmonics. It was concluded that neither the fault currents nor the current harmonics pose any problems in the operation of the dc superconducting cables.