In-Grid Demonstration of Long-length "3-in-One" HTS Cable (Albany Project)

High-temperature superconducting (HTS) cables achieve large-capacity, low-loss power transmission in a compact size and are expected to offer not only economical advantages but also environmental advantages like energy conservation, resource conservation, and electromagnetic interference (EMI)-free performance.(1) Due to these advantages, HTS cable demonstration projects and practical application studies are being promoted around the world. Sumitomo Electric Industries, Ltd. has been pursuing the development of HTS wires since 1986 when HTS materials were first discovered. Since 1991, the Company has been working to develop three cores-in-one cryostat type (commercialized under the trade name “3-in-One ”) HTS cables.(2), (3) It has promoted the development of HTS cables and other HTS applications using its highperformance bismuth-based HTS wire (commercialized under the trade name “DI-BSCCO”) that is manufactured using a proprietarily developed sintering process named the “CT-OP” process.(4), (5) Sumitomo Electric’s “3-in-One” cable has become the first commercial HTS cable to successfully achieve in-grid operation through a practically used underground power grid in the Albany Project, one of the HTS cable demonstration projects conducted by the United States Department of Energy (DOE). In Phase I of this project, an HTS cable system consisting of two DI-BSCCO cables was energized on July 20, 2006 and began long-term in-grid operation.(6) From that time, a long-term demonstration progressed satisfactorily without human intervention and was completed on May 1, 2007. The HTS cable system achieved a total of nearly 6,800 hours of electricity transmission during Phase I. In Phase II, a new HTS cable with YBCO coated conductors was manufactured and replaced one of the DIBSCCO HTS cables. The world’s first HTS cable replacement was completed successfully. The cable system was re-energized and put back in service on January 8, 2008. Then, the in-grid operation progressed satisfactorily and was completed in the end of April 2008. In the Albany Project, during Phases I and II, the HTS cable system demonstrated more than 12 months of reliable operation on the live grid. This paper summarizes the results of the Albany Project’s long-term power transmission demonstration with an HTS cable system.