A new series-parallel active compensator for DC microgrids based on three-leg voltage source converter

Abstract

DC microgrids are gaining increasing attention due to their advantages such as high reliability, high efficiency, ease of renewable energy sources integration, and the absence of frequency and reactive power regulation problems. Connection of AC energy sources and loads to the DC microgrids through AC/DC converters can distort the DC microgrids voltage and current. In addition, the fault occurrence in the DC or upstairs AC microgrids can cause voltage sag and swell. Compensating and reducing these voltage and current distortions requires efficient and cost-effective solutions. This article proposes two new topologies of DC series-parallel active compensators for voltage and current compensation in DC microgrids. In the first topology, the back-to-back connection of an isolated bidirectional DC/DC converter with a full-bridge converter is used to compensate voltage and current. In the second one, to eliminate the transformer, simplify the converter structure and reduce its cost, an active compensator based on a three-leg voltage source converter is proposed which can compensate both the microgrid voltage harmonics, sag and swell, and the load current harmonics. The proposed topologies performances are confirmed through their simulation in the MATLAB/SIMULINK environment. A simple experimental setup is also provided to validate the simulation results.