Practical Forecasting of AC Losses in Multi-layer 2G-HTS Cold Dielectric Conductors

Abstract

With the recent progresses on the designing and manufacturing of lightweight and high engineering current density superconducting cables, the need for an established, fast, and sufficiently accurate computational model for the forecasting of AC-losses in cold-dielectric conductors, is pivotal for increasing the investment confidence of power grid operators. However, validating such models is not an easy task, this because on the one hand, there is a low availability of experimental results for large scale power cables and, on the other hand, there is a large number of 2G-HTS tapes involved whose cross-sectional aspect ratio hinders the numerical convergence of the models within reasonable delivery times. Thus, aiming to overcome this challenge, we present a detailed two-dimensional H-model capable to reproduce the experimentally measured AC-losses of multi-layer power cables made of tens of 2G-HTS tapes. Two cable designs with very high critical currents have been considered, the first rated at 1.7 kA critical current, consisting of fifty 4 mm width 2G-HTS tapes, these split in 5 concentric layers wound over a cylindrical former, with the three inner layers forming an arrangement of 24 tapes shielded by two further layers with 13 tapes each. This cable is contrasted with a size wise equivalent cable with 67 superconducting tapes rated at 3.2 kA critical current, whose design implies the use of 40 tapes of 3 mm width split within four core layers, and 27 tapes of 4 mm width distributed in two shielding layers. In both situations a remarkable resemblance between the simulations and experiments has been found, rendering to acceptable estimates of the AC-losses for cold dielectric conductors, and offering a unique view of the local electrodynamics of the wound tapes where the mechanisms of shielding, magnetization, and transport currents can coexist within the hysteretic process.