Experimental and Numerical Study of Current Distribution of Superconducting Composite Conductor With REBCO Tapes for Power Electric Applications

Superconducting power devices, such as superconducting transformer and superconducting magnetic energy storage system, are the key technologies in the power system. High-current high temperature superconducting (HTS) composite conductors have been developed for use in HTS power devices. This paper studies the electromagnetic fields of superconducting composite conductors, with high current and compact configuration, for power applications. We focus on the current distribution simulation within the tapes especially. A three-dimensional finite- element method numerical model with new boundary condition technique is proposed to analyze superconducting composite conductor using the T-A formulation. The T-A formulation is verified by experiments on a superconducting twisted stacked-tape cable composite conductor. The numerical model simulates the current redistribution among the stacked layers to show the circulation currents. According to the numerical results, it is found that the circulation current between different layers could be 45% of the peak current, which was considerably significant for a composite conductor operation. For a composite conductor with a different number of tapes, the circulation currents flow through the outmost layer and come back from the other inner layers. Comparing the circulation current between twisted and untwisted stack-tape cable, it is found that the twisting could reduce the circulation current.