Analysis of magnetic field and geometry effects in the design of HTS devices for AC power applications

The performance of HTS devices is strongly influenced by local values of the current/field distributions. In this paper, we investigate the influence of the magnetic field and of the geometrical configuration on the loss behaviour of a 200kVA FCL prototype, composed by Bi-2223/Ag tapes wound around a cylindrical support, as function of different operating ac currents. The investigation is done by means of FEM computations, with the use of an axisymmetric 2D A-V formulation for taking into account the cylindrical geometry. The electrical behaviour of the superconductor is described by means of a B-dependent E-J power-law relation, derived from experimental measurements with field of different orientation. Several geometrical configurations are analyzed and compared, in order to find the ones with lowest AC loss. The developed method can be applied for investigating devices other than FCL, such as superconducting transformers and magnets, where the local distribution of the magnetic field and the arrangement of the conductors play an important role. This work is supported partially by the Swiss project “MaNEP” and partially by the Italian project “Ricerca di Sistema”.