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The high temperature superconducting (HTS) power cable has been successfully installed and operated for feasibility confirmation since 2006 at the power testing center of Korea Electric Power Corporation (KEPCO). The three phase 100 m long HTS cable with 22.9 kV/1.25 kA was manufactured and cooled by the open-loop of sub-cooled liquid nitrogen generated by a decompression cooling unit. No major fault has been observed during long-term operating test. As a next step, the design study of a 500 m long HTS cable system has initiated in 2008. Now, the HTS power cable was manufactured and installed at Icheon substation located near Seoul. In this paper, the cooling performance test of the 500 m long HTS cable in the real power grid is reported. Pre-cooling process using nitrogen gas is presented and the result of initial cool-down of the HTS cable is reported. Also, temperature as well as pressure drop in the system is discussed with respect to the loading current level. [ABSTRACT FROM PUBLISHER]

The Korea Electric Power Corporation (KEPCO) HTS power cable has been successfully installed and operated for feasible confirmation since 2006 at Gochang power test center. The 3-phase 100 m long HTS power cable with 22.9 kV/1.25 kA was manufactured and cooled by subcooled liquid nitrogen. At the beginning stage, the cooling system was composed of a liquid nitrogen decompression cooling unit. No major fault has been observed during long term operating test. As a next step, cooling system was modified that a cryocooler was employed, resulting in the total cooling capacity of 4 kW at liquid nitrogen temperature. In this paper, the progress on the performance test of HTS power cable is reported. Temperature as well as pressure in the system is discussed with respect to the supplied current levels. Also, the installation of hybrid cooling system for real power grid application is described. [ABSTRACT FROM AUTHOR]

In Korea, the KEPCO (Korea Electric Power Corporation) HTS power cable system has been successfully operated for evaluating the technical and economic feasibility as well as accumulating the operation experience since 2006. A cooling system composed of a liquid nitrogen decompression cooling unit and a closed-circulation system of subcooled liquid nitrogen at the KEPCO's Gochang power testing center. As the next step, we adjusted the cooling system for the purpose of testing a different cooling system using a cryocooler unit with cooling capacity of 4 kW at 77 K in the existing cooling system. It was designed to be used as a hybrid cooling system. In other words, it has as an each system of cryocooler unit or decompression pump unit. In this paper, the performance test results are summarized and the outline of the hybrid cooling system is introduced. [ABSTRACT FROM AUTHOR]

In order to meet the needs of economical and stable power supply and high current density cable with compact size, several countries carry out researches on High Temperature Superconducting (HTS) cables. Korea Electric Power Corporation (KEPCO) established the HTS cable test center and installed 22.9 kV, 1250 A, 50 MVA, 100 m class HTS cable system to investigate the performances and application possibility in real power grids. The HTS cable system went through seven cool down and warm-up cycles and also many kinds of performance tests. for 3 years. Rated voltage-current tests, over voltage tests, and measurements of heat loss and AC loss with various currents have been examined. Moreover, DC critical current tests were performed for checking conductor degradation before warming up or after cooling down. Through the performance tests of the HTS cable system, the overall efficiency and loss factors are estimated and compared with conventional power cables in this paper. We conclude the present status of HTS cable system and application possibility in the real power grid. [ABSTRACT FROM AUTHOR]

As high temperature superconducting (HTS) power cables have some merits over conventional cables, several demonstration projects on the HTS cable system are presently under way around the world. Korea Electric Power Corporation (KEPCO) also initiated an HTS cable project in 2002 with the Korean government's support. A three phase 100 m HTS cable system with a capacity of 50 MVA has been installed at Gochang test yard, located in Chonnbuk province, Korea. The HTS cable system is composed of a 100 m-long cable, two terminations and a cooling system. The rated current is 1,250 Arms and the rated voltage is 22.9 kV considering compatibility with the conventional power distribution system in Korea. Main purposes of this project are to verify the performance of an HTS cable system and to evaluate the potential of the HTS cable system from the viewpoint of power utilities. The real grid application of the HTS cable system requires the demonstration of system reliability, accumulated operation experiences, and it has to meet the practical needs of the utilities. In such a meaning, this project provides various challenges for KEPCO, and the feedback will be delivered to cable manufacturers. This user initiative test will facilitate the introduction of HTS cable systems into a real grid network. The installation process of the HTS cable system and some results of the preliminary test were presented in this paper. [ABSTRACT FROM AUTHOR]

A high temperature superconducting (HTS) power cable system cooled by forced-circulation subcooled liquid nitrogen is under construction in Korea. In the system, the termination cryostat designed for normal capacity of 22.9 kV, 1.26 kA is located at each end. In order to cool the cryostat effectively, we conducted several numerical analyses. It was found that major design factors were position of inlet and outlet for the liquid nitrogen as well as mass flow rate of the liquid nitrogen in the cryostat. It was also found based on the calculation of temperature distributions in the cryostat that the mass flow rate of liquid nitrogen is needed at least 0.2 kg/s. The cryostat was designed to endure the mechanical stress induced by thermal shrinkage from room temperature to liquid nitrogen temperature. The cryostat is being installed in the 30 m length, prototype single phase HTS cable system. [ABSTRACT FROM AUTHOR]