Over-voltage distribution between turns of the transformer coils of large SST cells

Solid state transformers (SST) are becoming key elements for integrating an increasing part of intermittent renewable energy in electric grids [1]. They bring also compact solutions for transportation systems [2]. Our society needs powerful SSTs for a reasonable cost. A good technical-economic balance can be reach by designing large power SST cells with mature technologies for power electronics, magnetic cores and Electrical Insulation Systems (EIS). The paper develops a method able to compute the turn-to-turn voltage distribution in the transformer of large SST cells during the fast transient states imposed by converter switchings. The proposed method makes it possible to design high voltage SST windings with a mature low voltage dry EIS based on polymers.