Design and Modeling of a Persistent Switch of HTS Coils for a Magnetic Energy Storage System

A high temperature superconducting (HTS) material like YBCO type, of second generation (2G) coated conductor, was chosen for the execution of the superconducting coils which are part of a superconducting magnetic energy storage system (SMES) under construction in ICPE-CA. A very important issue for a superconducting magnetic energy storage system is the persistent mode operation of the HTS coils together with the junctions resistivity. The switch between "persistent mode" and "driven mode" operation of a superconducting coil is performed by the so called "persistent switch" (PS). This paper describes the design and the numerical modeling of a PS meant to work with the HTS coils, and some experimental results regarding the physical properties of the YBCO tape, necessary for the design of the PS. The numerical modeling results refers to magnetic field generated by the coils and the thermal behavior of the PS. The Comsol Multiphysics software was used to obtain the numerical results.