An Improved Control Strategy for Renewable energy sources (RES) based DC microgrid with enhanced System Stability and Control Performance

Abstract

With the increasing penetration of renewable energy sources (RESs) into electrical power systems, DC microgrids bring an appealing solution to overcome the integration challenges. Due to the massive integration of RES into the electrical power system among DC microgrids, critical challenges have been aroused in controller design and its operation. In large-scale DC microgrids, complexities and control requirements are complicated than small scale grid. Existing primary and secondary cooperative control structures rely on PI controllers that make them vulnerable at higher nodes. In this paper, by considering the DC microgrid control requirements, structural improvements have been suggested to improve controller stability and performance. A droop-less control scheme has been proposed in this paper by augmenting a finite gain controller in voltage loop with PI controller in the current control loop of DC/DC converter. A different strategy has been employed at distributed secondary control for the estimation of average voltage and current difference. The proposed droop-less controller offers several benefits such as simplicity in the control structure, higher stability, higher scalability, and overall better system reliability. The simulation results in MATLAB/Simulink setup verify the controller efficiency and feasibility. Moreover, voltage control bandwidth comparison is presented while considering communication delays and in the presence of a higher system nodes.