Superconducting Shielding Coils Influence on AC Loss Reduction of 3-Phase HTS 1 MVA Transformer

Reducing AC loss is a critical issue in the design of high-temperature superconducting (HTS) transformers. Owing to the diamagnetism of superconductors, superconducting shielding coils (SSCs) provide an effective means of reducing the perpendicular magnetic field component and AC loss. This work systematically investigates the influence of the SSCs on AC loss in a 1MVA HTS transformer, using two-dimensional (2D) T-A homogenization method. The effects of key parameters are analyzed, including the SSC turn number (up to 12), tape width (4, 6, 12 mm, including combination of different widths), vertical distancehabove the top of the transformer windings (0.1 − 4 mm), and the radial gapgbetween the SSCs and the transformer windings (0.5 − 5 mm). The AC loss in the 1MVA HTS transformer is calculated under these configurations. The simulation results indicate that incorporating SSCs significantly reduces AC loss. For example, employing four 12-mm-wide turns of SSCs for both the LV and HV windings at rated current achieves a reduction of 35.2%. This effectiveness arises from the suppression of perpendicular magnetic field component to the end parts of the transformer windings.