Concept and Design of 500 Meter and 1000 Meter DC Superconducting Power Cables in Ishikari, Japan
The design and construction of two DC superconducting power cables were started in the spring of 2013 as a national project in Japan. The cable lengths are 500 and 1000 m, respectively. The project is called the Ishikari Project. Four parties, Chiyoda Corp., Sumitomo Electric, Sakura Internet, and Chubu University joined to establish a partnership. The 500-m cable will connect an Internet data center (iDC) to a large scale array of photovoltaic cells to supply dc power. During the design and the construction in the field, test benches have also been constructed to investigate the performance of the individual components of the cable system. The design value of the heat leak of the cryogenic pipe is 1.3 W/m and the experimental result is 0.7 W/m to 1.3 W/m on the test bench. The design value of the heat leak from the current lead is 35 W/kA and the experimental value is 30.5 W/kA at the rated current. Control of the thermal contraction and expansion are important to maintain cable safety and two methods are considered. Construction was started in the field in mid-May, and the 500-m cable will be completed at the end of the fiscal year 2014.