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High temperature superconducting cable demonstration project supported by Ministry of Economy, Trade and Industry and New Energy and Industrial Technology Development Organization has started since FY 2007 in Japan. Target of this project is to operate a 66 kV, 200 MVA HTS cable in a live grid in order to demonstrate its reliability and stable operation. A demonstration site has been decided to Asahi substation which is located in Yokohama. The cable length will be decided to between 200 and 300 m depending on a site configuration. Various preliminary tests such as critical current, ac losses, fault current loading, mechanical tests, have been conducted by using short core samples in order to confirm a HTS cable design and a cable-to-cable joint structure. From these test results, a HTS cable, a joint and a termination have been designed to meet the required specifications. To verify their performances before the installation of the HTS cable system in Yokohama, a 30-m HTS cable was manufactured and various sample tests were conducted as shipping test. The critical current of the HTS conductor and shield were 6.1 kA and 7.1 kA, respectively. The AC loss was 0.83 W/m/ph at 2 kA rms , 60 Hz. As withstand voltage tests, AC 90 kV for 3 h and lightning impulse at ±385 kV were applied to cable core, successfully. These test results has confirmed that the 30-m cable had good properties as designed and satisfied the required specifications. After the success of the shipping tests, the 30-m HTS cable pre-demonstration system has been installed at SEI factory. The cable system will be operated and checked the various performances in this summer.

A new 100 m underground HTS cable system was planned for an experimental study in a real scale. The main targets of the project were the verification of the system application. Various types and multipoint analogue data including digital control sequence data were required to be measured. Because of the long operating period of the system cooling and warming sequence, very high operating stability was required. Additionally the economically designed main cooling facility was requested over-night manual operation. The basic function of the data acquisition and control system was the gathering of various type data and the control of test facilities include the cooling facility. Most effort of the design procedure was focused on making the automatic operation including under an emergency situation and the alerting of the emergency state to the operators staying even remote place. The main focus of this function was reducing of the operating man power, specially requested for over-night. So various emergency situations and scenarios were considered and analyzed for the automation operation.

Several verification tests are being underway world widely in order to apply HTS cable to real grid. KEPCO (Korea Electric Power Corporation) has initiated HTS cable project since 2002 with the aid of MOCIE (Ministry of Commerce, Industry and Energy), Korea. The HTS cable system with the specification of three-phase, 1.25 kArms, 22.9 kV and 100 m was installed at the KEPCO’s Gochang test yard. In consideration of economical efficiency on retrofit for typical underground cable, the HTS cable was designed to be applicable for 175 mm ELP duct and 55 m-long cable was laid on underground trench in the same manner as the conventional pulling method. Cool-down to LN2 temperature and warm-up to room temperature were performed several times to investigate the influence of thermal cycle. The main objectives of this project are to verify performance of the HTS cable system and evaluate the economical and technical feasibility from all angles. Expected pros and cons of HTS cable including reliability and maintainability will be assessed with the view point of utilities. This paper summarizes some results of installation and after-laying tests.

Superconducting cable is expected to be one of the most economical ways to improve both the stability and capacity of electrical transmission and distribution lines, so several studies of high-temperature superconducting (HTS) cable have been initiated around the world. SEI was recently engaged by the Korea Electric Power Corporation (KEPCO) to install a 22.9 kV–1250 A HTS cable system, comprising a 100 m HTS cable, two terminations and a cooling system, all manufactured in Japan and shipped to the KEPCO Gochang test site in Cheolabuk-Do, ROK (Republic of Korea). After system installation and assembly, the cable was cooled with liquid nitrogen. Following several checks, including measurements of critical current and heat loss, and AC voltage and current tests, a commissioning test saw the cable carry 1250 A at 22.9 kV for 48 h, meeting all requirements. This report outlines the KEPCO HTS cable project, including system design, manufacture, installation and testing.

Albany HTS cable project is going on with the support of US Federal and New York States. The HTS cables included the Bi2223 tapes sintered by CT-OP (controlled over-pressure) process has 34.5 kV and 800 A capacity. The cable system was manufactured in Japan, and shipped to Albany. A 320 m cable and a 30 m cable were installed into the conduits under the ground. Subsequently, a splice box was assembled in the vault, and two terminations were connected to the HTS cable on the ground. Cryogenic refrigeration system was also mounted at the site by BOC. Initial cooling process was conducted as measuring distributed temperatures along the cable. The results of off-grid test, i.e. measuring heat loss, pressure loss, critical current, and DC withstand test, were carried out successfully. HTS cable system was connected to the real grid on 20 July 2006. The cable has been operated stably for 3 months as monitored by Remote Operation Center of BOC. This report outlines the installation and test results on Albany HTS cable project.

Starting from investigation of feasibility and basic studies, KEPCO/KEPRI has carried an enterprising project for HTS cable system since 2002. The objectives of this project are to demonstrate HTS cable system and evaluate the feasibility in electricity utility's view. The installation of 100m/3phase/22.9kV/50MVA HTS cable system is undergoing in KEPCO's test yard, located in Gochang, Korea. The HTS cable system consists of 100m long cable, two terminations and a cooling system. To simulate the actual cable installation, the 55m section of the 100m long cable was installed into an underground tunnel. Commissioning test is scheduled at the end of September, 2005 and followed by long term operation test. In this paper, the installation of HTS cable system and initial results of system operation will be summarized