Tomoya Nomura

Model Cable Tests for a 275 kV 3 kA HTS Power Cable

High-temperature superconducting (HTS) cables are considered the next generation transmission line because they are compact, lightweight, and demonstrate large capacity and low loss compared to conventional cables. In particular, since a coated conductor (YBCO wire) provides high critical current, high magnetic-field property, low AC loss, and low cost, it is expected to make the HTS cable more attractive than other superconducting wire. In Japan, 66/77 kV HTS cables have developed for about 20 years. We started developing 275 kV class HTS cables three years ago based on 66/77 kV HTS cables. The goal is a 275 kV 3 kA cable with a capacity of 1.5 GVA, the same capacity as a typical overhead transmission line, which serves as the backbone of Japanese power networks. The following technical developments will be carried out: high current and low AC loss cable conductors and high voltage insulation and low dielectric loss cables. Regarding high current and low AC loss cable conductors, 3-kA cables have been fabricated, and AC losses have been measured. We found that using thin YBCO wire reduced AC losses in experiments.

Status of a 275 kV Class REBCO Superconducting Cable Development

The REBCO high-temperature superconducting cable, rated at 275 kV and 3 kA, was developed in the Materials and Power Applications of Coated Conductors project in 2008. The cable is expected to be put to practical use as a backbone power line in the future because the transmission capacity is about the same as the UHV overhead transmission line. Transmission loss is significantly reduced by using superconducting wires instead of Cu or Al conductors. Furukawa Electric plans a demonstration of the 275 kV high-temperature superconducting cable. The cable system consists of a 30-m cable, terminations, a cable joint, and a cooling system. The 30-m cable has already been manufactured and installed on a test site. In this demonstration, various electrical evaluations will be conducted, such as a long-term test under a current of 3 kA, and the test voltage will be determined assuming 30 years of insulation degradation.