Cooperative Control to Suppress Unbalanced and Harmonic Distortion in the Distribution Network With Inverter-Based Distributed Generators

Abstract

In the contemporary distribution network, unbalanced and harmonic distortions have been considered some major power quality problems, which have escalated especially due to the high penetration of unbalanced and nonlinear loads. This study first analyzes the dispute around the distortion restraint and grid-connected unbalanced/harmonic current suppression quantitatively and proposes a distributed control strategy that facilitates an effective suppression of output voltage and grid-connected current, with accurate unbalanced/harmonic power sharing. Compared with the majority of existing studies only addressing the voltage-controlled mode (VCM) inverters, our scheme can also be applied to current-controlled mode (CCM) inverters without adding additional current regulation loops. The proposed control strategy is independent of line parameters and robust to load changes. The corresponding small-signal dynamic model is constructed to analyze the system stability and the controller hardware-in-the-loop simulations aid in determining the outcome of the proposed strategy.