Analysis of Current Distributions in HTS Tapes of Superconducting Bipolar DC Energy Pipeline

The current distributions are analyzed in the Bi2223 tapes of the superconducting bipolar DC energy pipeline with the HTS bipolar DC cables cooled by the transferred liquid natural gas (LNG), with the focus on the three dimensional (3D) modeling of the helical type of HTS tapes. It is especially important to improve the utilization of the HTS tapes by making the currents uniformly distribute among the tapes. Based on the E-J power law [1], the current distributions in both straight and helical Bi2223 tapes of the double-core bipolar DC cables are calculated by two-dimensional and three-dimensional models respectively with the commercial software COMSOL Multiphysics. The results indicate that the current distributions in the straight tapes are not uniform with the highest value being 40% higher than the lowest one for the sample case, where the bipolar voltages are ±110 kV and the current is 1 kA. Whereas the currents in the helical tapes are much more uniform. Both parallel and perpendicular magnetic fields on the helical tape surfaces are evaluated.