DVR with open-end winding transformer

Abstract

This paper presents a dynamic voltage restorer (DVR) obtained through a series connection of two three-phase inverters. Such connection is obtained due to open-end winding arrangement of the transformer. As done in a conventional configuration, the proposed one aims to regulate the voltage at the load terminal in the case of sags/swell, distortion, or unbalance in the grid voltage. A suitable control strategy is presented, as well as the operating principles, characteristics and a comparison between the proposed and conventional configurations. The main advantages of the proposed topology are: a) reduced harmonic distortion (operating at the same switching frequency), b) reduced converter losses (operating with the same harmonic distortion), and c) fault tolerance capability. The proposed DVR system is suitable for medium voltage application. Simulated and experimental results are also presented.