Minimum power loss based design of SMES as influenced by coil material

Superconducting magnetic energy storage (SMES) system is one of the commonly used techniques by the end-users to mitigate the voltage sag at their premises from the distribution system. The SMES is a superconductor coil wound on a nonmagnetic core. The paper is aimed at optimizing the dimensions of the coil to achieve minimum coil loss. The Genetic Algorithm (GA) is utilized to minimize the coil loss as a multi-objective function with indices including AC loss and refrigeration loss. The results show that the optimal total loss of SMES coil at capacity energy of 4 MJ is 85.04 W against 114.5 W in a previous work. The corresponding optimal dimensions of the coil which include the inner diameter, outer diameter and coil length are 0.19, 0.2 and 2.17 m, respectively. Different low-temperature superconductivity coil materials at operating temperature of 4.2 ^oK are considered to select the best material with minimum coil loss. The results conclude that Nb–Ti material achieves minimum coil loss when compared with MgB₂ and YBCO. The effect of the twist pitch and circumferential stress on the total losses in the SMES coil is studied.