Qualification Test of a 80 kV 500 MW HTS DC Cable for Applying Into Real Grid

Until now, some countries including South Korea have made considerable progress in the development of HTS (High Tc Superconducting) power equipment. Superconducting power cable systems are the strongest candidate from the viewpoint of their use in the real grid owing to their high current capacity. Specially, in the future, high-current long-distance HTS DC cables will play an important role in power transmission systems because, in contrast to HTS AC cables, HTS DC cables experience nearly no loss. In this paper, the authors suggest a new testing method for the load cycle and suitable thermal cycles to meet the requirements for HTS DC cables to be applied to the real grid. A prototype 100 m/3.25 kA/80 kV HTS DC cable system was developed for the qualification test in South Korea. The qualification test was carried out, based on HTS experience, the international standard for HTS AC cables, and the standards for conventional HVDC cables. It was performed in the same manner as that for a conventional HVDC cable for 6 months in the KEPCO PT (Power Testing) Center. Since its successful qualification test, the 500 MW/80 kV HTS HVDC cable system will have been operated in the KEPCO real grid since 2015, to evaluate its practical requirements and confirm its technical feasibility. This paper presents the recommendations and results of the qualification test for HTS DC cables.