Analysis of AC loss and current distribution in multi-layer tri-axial three-phase HTS cable

A numerical model to calculate inter-layer current distributions and AC losses in tri-axial multi-layer three-phase cable conductors was developed. The numerical model was applied to the two-layer/phase tri-axial cables with several combinations of twist pitch and twist direction to investigate the influence of the cable twist configuration on the inter-layer current distribution and the AC loss under three-phase AC operation. From the numerical results, the twist pitch combinations to equalize the inter-layer current distribution could be found. The numerical results also showed that the AC loss can be much reduced by equalizing the inter-layer current distribution. It was also notable that the AC losses in the cables with different twist configurations were different, although the inter-layer current distribution was equalized. For the cable design, it is necessary to select proper twist configuration considering both equalization of current distribution and minimization of AC loss together.