Three project themes, “Development of a Redox Flow Battery System,” “Japan’s First Success in Demonstrating Operation of High-Temperature Superconducting Cables in the Grid,” and “Development of Cross-linked Polyethylene Ultra-high Voltage Direct Current Power Cable and its Application in an Actual Line,” each received the 70th Prize of Progress from the Institute of Electrical Engineers of Japan.
The prize-winning themes are described below.
■Development of a Redox Flow Battery System
Yasumitsu Tsutsui, Toshio Shigematsu, and Toshikazu Shibata (Sumitomo Electric)
Redox flow batteries are expected to stably supply power from unstable power sources. The prize winners worked on the development of new materials for redox flow batteries and of a system designed to use them in smart grid applications. In 2011, they constructed a DC microgrid consisting of small wind and solar power generation units and a 2 kW/10 kWh redox flow battery system. In 2012, they began testing a full-scale system consisting of a 100 kW photovoltaic system and 1 MW/5 MWh redox flow battery system connected to the power line of a factory. The test included a demonstration of the factory energy management system (FEMS) and completed successfully.
■Japan’s First Success in Demonstrating Operation of High-Temperature Superconducting Cables in the Grid
Tomoo Mimura (Tokyo Electric Power Company, Inc.), Masahiro Shimoda (Mayekawa Mfg. Co., Ltd.), and Yuuichi Ashibe (Sumitomo Electric)
In “High-Temperature Superconducting Cable Demonstration Project” conducted by New Energy and Industrial Technology Development Organization (NEDO), Sumitomo Electric, Tokyo Electric Power and Mayekawa Manufacturing installed a 66 kV, 3 kA class three-cores-in-one-cryostat type superconducting cable system incorporating bismuth-based high-temperature superconductors at Tokyo Electric Power’s Asahi substation.
In Japan’s first demonstration test of power transmission via superconducting cables connected to the power grid, conducted for 14 months from the end of October 2012, the superconducting cable system successfully and stably supplied electricity to some 70,000 households.
■Development of Cross-linked Polyethylene Ultra-high Voltage Direct Current Power Cable and its Application in an Actual Line
Yoshimichi Ohki (Waseda University), Hidetaka Sasaki (Electric Power Development Co., Ltd.) and Shoji Katagai (J-Power Systems Corporation)
Cross-linked polyethylene (XLPE) cables are subject to electrical breakdown during operation at high temperatures or in the case of polarity inversion (inversion of positive and negative poles of the voltage according to the operational conditions). To tackle this problem, the prize winners worked on comprehensive development of materials, design, manufacturing and installation. The result was successful development of an XLPE ultrahigh-voltage direct current cable that reduces space charge accumulation within the insulation by adding a very small amount of an inorganic component to the insulation material. This cable was adopted in the ±250 kV line interconnecting Hokkaido and Honshu, which commenced commercial operation in December 2012.