Optimization for Solenoid-type Superconducting Magnetic Energy Storage Coil

The operating cost of superconducting magnetic energy storage (SMES) system highly depends on the ac loss due to magnetic field transients and heat in-leak to the system. Therefore, reduction of ac loss and coil or cryostat surface area since it reduces heat inleak into the system is an important design criteria for superconducting magnetic energy storage system. This paper presents a new and elegant optimization approach of finding geometrical parameters of a solenoid type superconducting magnetic energy storage coil that minimizes both ac loss as well as coil surface area for a given allowed hoop stress and stored energy. A fundamental prerequisite of the design is that if the initial design constraints such as stored energy and allowable circumferential or hoop stress in the winding are fixed and critical characteristics Jc(B) of the superconducting cable are given, the optimization technique using Differential Evolution (DE) method provides unique solution of design parameters and operating condition. For a given critical characteristics of the cable, dependence of optimized geometrical and operating point (Bm, I) in various stored energy levels has been investigated. Effect of allowed hoop stress on optimized parameters has also been investigated.