Voltage perturbations compensator on the base of three-phase hybrid transformer

This paper deals with a three-phase hybrid transformer (HT) to compensate voltage sags and swells and to protect sensitive loads against the rapid and extensive changes in supply voltage amplitude. The analysed HT contains two main units: the first-one is the conventional electromagnetic transformer, realizing an electromagnetic coupling; and the second-one is the buck-boost matrix-reactance chopper, realizing an electrical coupling in the HT unit. The paper presents an operational description and the experimental test results from a 2 kVA laboratory model. The main advantages of the proposed solution, in comparison to other conventional solutions, are the ability to control the output voltage in the range from 0.66-3.5U_S, good dynamics (transient state during source voltage U_S amplitude change is shorter than 10 ms) and galvanic separation between source and load (such as in the case of the conventional electromagnetic transformer).