Coated Superconducting Tape Model Based on the Distribution of Currents Between the Tape Layers: Computing Implementation

In large-scale applications of high-temperature superconductors (HTS) such as superconducting fault current limiters or superconducting magnetic energy storage, HTS tapes are often the simplest element involved in the design of such elements. In turn, those elements are part of wider environments, as power grids, which are analyzed by programs using models of well-known conventional electrical elements, e.g., resistances, reactors, transformers, switchgear, etc. The problem of superconducting elements to be modeled as the other ones is the nonlinearity of their response, due to the nonlinearity of the superconducting tape in which the elements are done. The proposal of this work is to develop a model of the coated superconducting tape based on parameters that adjust the nonlinearity of the tape under the hypothesis that: 1) the electrical current is distributed between the layers of the tape (mainly between the superconducting layer and the stabilizer) in a different way depending on the peak value; and 2) the hysteresis in the superconducting layer can be modeled as a function of the stationary V(I) characteristic. Experimental measurements have been done in order to adjust the parameters of the model, which have to be determined for each type of tape in the same way that the parameters of ferromagnetic cores have to be determined for each material. Several models have been implemented in a MATLAB environment and tested to be part of a more complex circuit. The best solution for straight tape and self-field was developed in Simulink, and results and conclusions are presented here.