The Superconducting—AC Equipment (Super-ACE) project was started in 2000 fiscal year as a national project to research and develop superconducting AC power equipment. The goal of the project is to develop basic technologies for high-temperature superconducting (HTS) cable, HTS fault current limiters (FCL), and HTS magnets for reactors and transformers. This paper describes major results of studies on the HTS superconductors, and outlines some of the results of verification testing completed for 500-m cable, FCL and HTS magnets.
A high-Tc superconducting (HTS) power cable is one of major candidates for next-generation underground power transmission systems having various advantageous features such as low impedance, low losses and compactness. The use of HTS power cables requires cooling stations, which can be located in manholes at intervals of several kilometers. Therefore, HTS power cables need to have a single span length of several kilometers. However, the flow properties of liquid nitrogen, which is used as the coolant for HTS power cables, have not been clarified for cryogenic tubes with a length of several kilometers. Based on this , an HTS power cable with a length of 500 m was constructed at the Yokosuka site of CRIEPI, Japan, and tested for almost one year. Moreover, short-circuit tests were performed using an HTS power cable with a length of 10 m to elucidate the behavior of HTS power cables under the condition of flowing short-circuit current. From these tests, positive results were obtained that will help contribute to the realization of HTS power cables and their introduction into actual power grids.