A Study on the Normal Zone Propagation Velocity of the Racetrack Type Coil With Difference Shapes of Coil Bobbin

The high-temperature superconductors (HTS) have large stability compared with to temperature superconductors. However, normal zone propagation velocity (NZPV) of HTS should be slowed due to its high stability. To make high stable superconducting magnet with HTS, one of the beneficial methods is to increase the NZPV of superconducting magnet by adjusting the winding strength in the racetrack coil. The racetrack type coil (RC) is widely used to make the superconducting field coil of wind turbine generators. The conventional RC consists of two parts, which are the round section and straight section. Suitable deformation configuration of the straight part can be suggested and calculated by finite element method simulation. The central magnetic field and total magnetic flux were calculated to investigate the deformation effect of RC. Two RCs with GdBCO were fabricated to measure NZPV. One of the RCs was a deformed straight section such as the D-shape. NZPV was compared with each RC. It was found that NZPV of deformation RC was increased to lower internal overheating. Finally, these results can be applied for developing large-scale wind turbine generation.