Feasibility Study of MgB 2 Cable for Pancake Coil of Energy Storage Device

Superconducting magnetic energy storage (SMES) devices of several tens of kJ class are generally suitable for voltage compensation for microgrids, which produce and distribute electric power to restricted areas. MgB 2 material has been developed with superconducting properties by decreasing the production cost. Since hydrogen energy would be widely utilized to realize society with low carbon emission and stored in liquid state for reducing its volume, the power distribution system consisting of MgB2 SMES for compensation of voltage fluctuations cooled by the liquid hydrogen would be effective by synergy effect. However, the MgB 2 introduction to large-scale devices is still not enough and under investigation. Our group carried out the investigations to develop MgB 2 cable and pancake coil for the SMES device with specific capacity. The bending strain-sensitive characteristic of MgB 2 material forces us to design the twisted conductors and pancake coils with various parameters properly within its tolerable bending strains of both before/after heat treatment. The conductor design for small pancake coils and large SMES coils is shown in this research, as well as the demonstration results of a small test coil fabricated as a prototype of SMES coil.