Research on the Strategy for Series-Connected Transformer Magnetic Saturation and Magnetizing Inrush Current Suppression in Dynamic Voltage Restorers

Dynamic Voltage Restorer (DVR) is an increasingly popular voltage compensator mainly used for mitigating voltage sags through the series-connected transformer that connects electric distribution system and AC sub-system or load. The high response speed required for voltage compensation makes DC magnetic bias and magnetic saturation apt to occur when series-connected transformer in DVR outputs voltages, which may cause the waveform distortion of output offset voltages, or even worse, the failure to compensate. In consequence, observations and suppression of transformer magnetic saturation and magnetizing inrush current are imperative during voltage compensation. To realize that purpose, this paper proposes a method by which the flux linkage of the transformer that is regarded as a state variable can be directly controlled, and then verifies it through co-simulation by using the software Ansys Simplorer, Matlab and Ansys Maxwell from three parts.