Superconducting direct current transmission system

摘要

A DC superconducting coaxial transmission system provides electrical transmission of 5,000 megawatts of energy while simultaneously delivering liquid hydrogen. The transmission system includes a coaxial transmission segment including an inner superconductor, an outer superconductor disposed in surrounding relation to the inner conductor, and a dielectric insulator disposed between the inner superconductor and the outer superconductor. Liquid hydrogen surrounds the superconductors. Three phase transformers and poly phase rectifier/inverters provide a DC voltage source to the superconductors from the electrical grid. In one embodiment, a switching circuit connected between the voltage source and the superconductor injects a cancellation current component into the direct current flow. The cancellation current component is polarized to flow in a direction opposite to the direct current flow to produce a current zero, thus enabling safe interruption of the high DC current while minimizing the magnitude of transient voltages during switching.

主权项

1. A direct current superconducting transmission system for connection to a three-phase source network, the transmission system comprising:
a coaxial transmission segment comprising an inner superconductor, an outer superconductor disposed in surrounding relation to the inner conductor, a dielectric insulator disposed between the inner superconductor and the outer superconductor, and a coolant medium in surrounding relation to one of the inner superconductor and the outer superconductor; a first three phase transformer bank connected to the source network; a first poly phase rectifier/inverter connected to the first three phase transformer bank and adapted to provide a positive polarity direct current voltage source to one of the inner superconductor and the outer superconductor of the coaxial transmission segment; a second three phase source transformer bank connected to the source network; a second poly phase rectifier/inverter connected to the second three phase transformer bank and adapted to provide a negative polarity direct current voltage source to the other of the inner superconductor and the outer superconductor of the coaxial transmission segment; and a switching circuit connected between the positive voltage source and one of the inner superconductor and the outer superconductor, the switching circuit comprising first and second interrupters and a current cancellation circuit, the current cancellation circuit in parallel with one of the first or second interrupters.