Test results of full-scale HTS cable models and plans for a 36 kV, 2 kA_rms utility demonstration

Cable systems using high-temperature superconducting (HTS) tapes are nearing technical feasibility. Several large-scale demonstrations are under way. This article summarizes the advancements and status of a development project aimed at demonstrating a 36 kV, 2 kA RMS AC cable system through installing a 30 m long full-scale functional model in a power utility substation.

The HTS cable line is designed to link two medium-voltage transformer stations in an urban environment. The expected benefits of such a system include reduced energy loss, ease of installation, increased power rating in a small cross section, and insensitivity to the surrounding soil conditions. Results will be presented from tests on several 2 kA-class AC conductors.

Electrical losses below 1 W/m at 2 kArms have been obtained in these cable conductors. The cable system consists of terminations, three HTS cables with conventional room-temperature dielectric and stress cones, and a closed-loop circulating cooling system maintaining the temperature between 74 and 84 K.

Critical issues before the commercialization of this technology is the improvement of the thermal insulation, the reliability and maintainability of the cooling system, and the reduction of materials costs.