Electromagnetic Design of High-Temperature Superconducting DC Bias Winding for Single-Phase 500 kV Saturated Iron-Core Fault Current Limiter

The dc bias winding of a single-phase 500 kV saturated iron-core fault current limiter is presented. The winding is mainly made of Bi-2223 tape, and some YBCO tape is used to optimize the magnetic field distribution. By using YBCO winding, maximal radial component of the magnet flux density on top of Bi-2223 winding is reduced from 0.29 to 0.22 T. Therefore, the corresponding maximum operation current of Bi-2223 could increase more than 20%. Since the critical current of YBCO and Bi-2223 winding is different, two power supplies are used to excite the windings, where the prospected operation current of YBCO and Bi-2223 winding is 160 and 1045 A, and the corresponding magnetomotive force is 468 000. In order to satisfy the operation condition, the winding must be cooled by liquid nitrogen at 72 K. The experimental results of the developed winding at 77 K show that the operation parameter is consistent with the electromagnetic designed.