Droop control of bi-directional DC-DC converter for improved voltage regulation and load sharing in DC microgrid

Abstract

DC microgrids are gaining popularity as most of the residential loads like Televisions, BLDC fans, LED bulbs, Mobile phones and other electronic gadgets are DC in nature, but to connect Distributed DC generator (DG) to DC bus, DC-link voltage is to be maintained at the reference value. In the proposed work, a transformer coupled dual input converter control strategy is modified by replacing existing Perturb & Observe Maximum power point tracking controller with V - dp/dv based droop controller, which amalgamates DC bus voltage regulation and Maximum power point tracking (MPPT) of PV source and battery state of charge (SOC) in single controller, and eluding controller switching between voltage regulation and MPPT modes. The proposed system will also work as Decentralized droop control for load sharing, and applicable for both islanded and grid-connected operations. Load Power sharing between DG sources is achieved according to its droop coefficient values in DC side of the inverter, thus suitable for DC Microgrid, and results are verified by simulating the above system in MATLAB/Simulink.