Decentralised Control Strategy for Voltage Unbalanced Mitigation in Stand-Alone Microgrid

Abstract

The depletion of fossil fuel and rapidly increasing load demands have led to the integration of Distribution Generation (DG) units and further installation of micro-grids. A micro-grid is an entity comprising of DGs, Distributed Storages(DS), and local loads which can sustain in a grid-connected as well as in a standalone mode depending upon the given circumstances. A standalone micro-grid is susceptible to many spiteful events such as Voltage Unbalance, Under-voltage, or Over-voltage conditions due to its low-inertial nature and thus requires sophisticated control strategies to maintain the nominal voltage. This article, proposes a decentralized Positive-Negative Sequence compensation strategy which is applied to a PV fed inverter in order to mitigate Voltage Unbalance thereby adhering to the permissible range specified by IEC-61000-3-13 along with the maintenance of nominal voltage at the Point of Common Coupling(PCC) during Unbalanced loading conditions. Due to the high intermittent nature of Solar, the PV-fed DG is also equipped with an MPPT algorithm to track and extract the maximum power available. Since this strategy is applied directly to the local DG, so no information exchange takes place among the other DGs thus making it a communication-free technique. To validate the efficacy of this strategy a computed model was simulated in a MATLAB/Simulink environment where the simulations portray promising results in the proposed standalone system.