Solid state tap changers for utility transformers

The voltage in the medium voltage (10 kV) and low voltage (400 V) utility networks is controlled with the change of the transformer ratio tap changing. Continuous development of high power switching devices and especially devices with turn-off capability allows the use of power electronics in new areas of application. Replacement of the mechanical or hybrid switch of the tap changer with solid state switches for two power and voltage levels is studied in the paper.