Analysis of Discharging Characteristics in a Bi-2223/Ag Coil for SMES With Consideration of Cooling Capacity of a Cryocooler

We investigated discharging characteristics of a Bi-2223/Ag coil by means of thermo-electromagnetic coupled analysis. The objective was to evaluate the thermal behavior of conduction-cooled high temperature superconducting (HTS) coils when they are applied to superconducting magnetic energy storage (SMES) systems for voltage dip compensation. The electromagnetic analysis adopted finite element method (FEM) considering the J-E expressions, which can quantitatively estimate the experimental data obtained from the tape in wide ranges of temperature (20-77 K), external magnetic field (0.02-3 T) and its applied direction (arbitrary). The thermal analysis also employed FEM, and was performed under new boundary condition where heat flow rate into a cryocooler does not exceed its cooling capacity. It was shown that transient temperature rise occurred in the coil during discharging, and such temperature rise was underestimated for generally applied boundary condition, i.e., fixed value of temperature