Multi-Objective Optimization Based Voltage Injection Technique for Minimizing Imbalance and Harmonics in AC Microgrid
Rohit Nandi, Manoj Tripathy, Chandra Prakash Gupta
Abstract
Negative-sequence components and harmonics are generated in the current and voltage of an islanded AC microgrid under unbalanced and nonlinear loading conditions. Without any external controller or feedback signal filter, such components give power-sharing errors and develop voltage distortion at the output of participating inverters associated with particular sources. This paper proposes a decentralized inverter control scheme with an advanced voltage injection technique that minimizes the voltage unbalance factor (VUF) and reduces voltage total harmonic distortion (THD) in a low-voltage AC microgrid using Pareto multi-objective optimization (PMOO). It has a mean function with a second-order filter to minimize the DC offset and distortion in the feedback signal. It manages power sharing in a multi-bus distribution network with an advanced angle droop control. It also accounts for the line impedance, i.e., connecting the inverter unit to the network and the effect of zero sequence components. The simulation is tested on a modified CIGRE LV multi-bus distribution system with four wire configurations and experimentally validated on a two DG, single-bus resistive distribution model.