Modeling and Control of a Hybrid Transformer based on a Cascaded H-bridge Multilevel Converter

Hybrid transformers are an attractive solution for improving power quality problems in distribution grids, due to the capability of power converters to provide precise current and voltage regulation. A hybrid transformer using a low-frequency transformer, which processes the biggest amount of power, and two converters connected in series and shunt, with an additional cascaded H-bridge converter connected in parallel, is presented. The use of a series converter on the primary side and a shunt converter on the secondary side allows to provide voltage regulation and load current compensation, respectively. Both converters improve the transformer power quality, extending its lifetime. Meanwhile, the cascaded H-bridge converter establishes a common DC-Link to support both converters operation. In this work, the model, control, and simulation results of the proposed configuration are presented, showing the improvement on the distribution transformer.