Influence of strand deviations from nominal geometry on ac losses in multistrand superconducting cables

The modeling of current distribution and ac losses in multistrand superconducting cables is strictly related to the evaluation of the cable electric parameters. A perfect knowledge of these parameters is however impossible due to the complicated manufacturing process. Strand deviations from the nominal geometry and interstrand conductance changes occur in the cable compaction process. Statistical approaches can however be applied to deal with these issues. This paper reports a sensitivity analysis aimed to determine the effects of strand deviations from the nominal geometry. The deviations, however, are not directly imposed on the mutual inductances matrix, as this approach can lead to misleading results if the final matrices do not correspond to physically possible configurations. The statistical deviations are imposed on the strands geometry, keeping the strands in physically possible locations by means of geometric constraints. A code for the electromagnetic analysis of superconducting cables is then applied to the calculation of current distribution and ac losses in the different configurations, evaluating the relevance of the main parameters variation.