State-Feedback Control of a Hybrid Distribution Transformer for Power Quality Improvement of a Distribution Grid

A hybrid distribution transformer (HDT) combines a power converter and a conventional low-frequency transformer (LFT) in a single device. The most recurrent configuration consists of a shunt converter fed by the auxiliary winding (AW) of the LFT and a series converter connected to the low-voltage grid. Nonetheless, load harmonics circulate through the power converter and LFT, affecting their lifetime. In this work, an HDT composed of a series converter connected to the primary side through coupling transformers and a shunt converter directly connected to the secondary side is presented. The HDT model and discrete-time state-feedback control are presented. The results show that the HDT can improve the power quality of the grid, focused on extending the LFT lifetime.