Thermal Management of High-Temperature Superconducting Power Cables

摘要

Research is being conducted on high-temperature superconducting (HTS) power transmission cables for application in the electric utility industry because of low losses and their ability to increase the energy transmitted in existing underground duct structures. This capability is due to the high current density of the HTS cables compared to conventional copper conductors. This comes at the price of refrigerating the HTS cable to temperatures below 80 K with liquid nitrogen. The background heat load to keep the cable cold must be removed, as well as electrical losses. Under ac operation, energy losses in an HTS cable are referred to as alternating-current (ac) losses. For a direct-current (dc) HTS cable, the resistive heat generation is small compared to conventional conductor material such as copper, but it may become significant at long lengths for operation near the critical current. The thermal management of an HTS cable is currently being accomplished by circulating liquid nitrogen through the cable. Several possible cooling configurations use both counterflow and parallel flow schemes. For space power applications, a passively cooled cable would be very attractive, and a preliminary conceptual design is briefly described.