Inrush-modeling of a single-phase 1-MVA-HTS (High Temperature Superconducting)- transformer for rail vehicles

A 1-MVA-HTS-transformer has been designed, manufactured and tested according to specifications for rail vehicles as has been reported. The HTS-transformer for railway drive systems has to meet the demands of the rough operational conditions-comparable to conventional copper-oil-transformers. One main focus is the energizing of the transformer by switching via the vacuum main circuit-breaker to the grid. Due to the very small AC-ohmic resistance of HTS-transformers, a higher efficiency is offered. In contrary, the reduced ohmic resistance acts as an insufficient damper of the inrush current. Based on measurements of the inrush current of conventional transformers in rail vehicles, a special HTS-transformer-model has been used to predict the behavior of the inrush of a future HTS-transformer. Investigations of interacting parameters and damping possibilities according to the requirements of railroad companies were done. An additional damping resistor can be the best economical solution to damp the inrush current.