Advanced configuration of superconducting magnetic energy storage

\Superconducting Magnetic Energy Storage (SMES) is very promising as a power storage system for load leveling or a power stabilizer. However, the strong electromagnetic force caused by high magnetic field and large current is a serious problem in SMES systems. To cope with this problem, we proposed the concept of Force-Balanced Coil (FBC), which is a helically wound toroidal coil. The FBC can minimize working stresses by selecting an optimal number of poloidal turns. However, the winding of the FBC has a complex three-dimensional shape that can make the manufacturing of the helical windings difficult. To overcome this difficulty, a helical winding machine was developed. From winding tests, the possibility of the coil construction was demonstrated. Moreover, a small helical coil using high temperature superconductors was designed and fabricated in order to estimate the problems of helical winding technique through the experimental results with liquid nitrogen cooling. This paper describes the design condition of the Force-Balanced Coil in order to reduce structure requirements and proposes a solution to the problems of helical winding technique by using experimental devices.