Development of cooling technologies for SMES

A Superconducting Magnetic Energy Storage (SMES) system has good characteristics as energy storage equipment in electric power systems such as high efficiency, quick response and no deterioration in repetition operation. Since 1991, the Agency for National Resources and Energy Japan has carried out a national project to develop an SMES for power control in power systems. Moreover, SMES has been developed to bridge for instantaneous voltage dips since 2003. A field test of 5 MVA SMES for bridging instantaneous voltage dips was carried out on an advanced large liquid crystal TV plant in Kameyama from July 2003. Before that, a 10 MVA SMES system was working there. After the field test, the commercial SMES for instantaneous voltage dips is working there. In 2015, three commercial SMES units for bridging instantaneous voltage dips are operating in Japan. These SMESs are all equipped with metal superconducting coils. When considering cost-reduction, size-reduction, and maintenance of the SMES in the future, it is necessary to develop a SMES with a high-temperature superconductor and improve the efficiency of its cooling system. We have also developed and conducted operation tests of SMES with a Bi2212 oxide superconductor and high performance cryocooler which enable energy conservation operation by inverter control. In this paper, developed results on cooling systems and cryocooler for SMES are presented.