Electromagnetic behavior and ac loss in a multi-layer superconducting power cable

The electromagnetic behavior of a superconducting power cable consisting of a layered structure is described. As input for the model the voltage-current characteristics of the tapes used to make the cable, and the self and mutualinductance of the layers are used. Current and voltage wave shapes can then be calculated. for each layer as a function of externally applied ac by numerical integration of the equations describing the coupled layers. Due to the non-linear V-I characteristics of the layers layer currents become non-sinusoidal in the vicinity of the layer-critical current. Losses are computed by multiplying voltage and current in each layer separately and integrating over one period. Transient conditions have also been modeled - for example a quick shutdown of the cable current can result in circulating currents between layers even though no external current is flowing. Decay constants for this current depend on the resistance between layers and in the case of insulated layers on the joint resistance. (C) 2001 Elsevier Science Ltd. All rights reserved.