Overvoltages and Overcurrents in HV/MV Hybrid Transformers due to Grid Faults

Power electronic converters in grid applications as for example hybrid transformers are vulnerable to grid faults, so that a protection system is required. This paper identifies critical overcurrents and overvoltages due to grid faults and presents grid models to calculate the overcurrents and a high frequency transformer model to calculate the overvoltages, in order to derive requirements/specifications for designing protection systems.