Design study of a HTS cable in Yokohama project

A new high temperature superconducting (HTS) cable project supported by Ministry of Economy, Trade and Industry (METI) and New Energy and Industrial Technology Development Organization (NEDO) has started in Japan. Target of this project is to demonstrate the reliable and stable operate of a 66 kV, 200 MVA HTS cable in the grid. Tokyo Electric Power Company (TEPCO) provides the real grid and studies the impact of connecting the HTS cable to the existing conventional facilities in Yokohama. Sumitomo Electric Industries, Ltd. (SEI) manufactures the HTS cable, terminations and joint. Mayekawa Corporation provides a cooling system. One of the technical targets in the project is to reduce the AC loss of superconducting cable. For this purpose, a new type DI-BSCCO, which is a production name of BSCCO wires made by SEI, with twisted superconducting filaments is planed to be applied in the cable. A short cable core using the new wires shows less AC loss than 1 W/m/ph at 2 kA_rms. Another important point is to design a cable system to withstand a large over current at a short circuit failure. At a preliminary test with a short cable, it was recognized that the cable had no degradation of conductor I_c after applying the fault current of 31.5 kA for 2 s, which are required for 66 kV line. This report shows details of these experiment results and design of the cable.