Conceptual Design of HTS Coil for SMES Using YBCO Coated Conductor

High T_c superconducting (HTS) toroidal coil using YBCO coated conductor is designed for 70 MJ class superconducting magnetic energy storage (SMES) for power system control. Its configuration and shape are optimized by means of genetic algorithm (GA) to minimize the required length of the conductor. The optimization is performed for two kinds of constrains, i.e., maximum electric field or flux flow loss of the coil, which are calculated by means of finite element method (FEM). The FEM analysis considers quantitative current density (J)-electric field (E) expressions based on percolation transition model. It is shown that the great transport performance against magnetic field of YBCO coated conductor can realize a very compact SMES coil compared with an existing Nb-Ti´s one.