DEVELOPMENT OF AN IMPROVED HIERARCHICAL CONTROL SYSTEM USING THE METAHEURISTIC PID TUNER FOR DC MICROGRIDS

Abstract

This paper presents the development of the improved hierarchical control system using the metaheuristic centralized PID tuner for DC microgrids. Hierarchical control is one of the best control strategies employed in photovoltaics (PV) based DC microgrids with three layers of primary, secondary, and tertiary controllers in which PID control is at the center of each one of these three layered control levels. The principal objective of the primary controller is to ensure near-equal power sharing among the units and of the secondary controller is to correct the deviations in the common DC link, while the tertiary controller is used to manage the energy flow among DC microgrids or between DC microgrid and the main utility grid. Partial shading, the uncertain nature of solar irradiation, and varying temperatures significantly reduce the overall power efficiency of traditionally tuned PID control-based hierarchical systems, since the tuning gains of these PID controllers are not adaptive to the dynamic processes. To optimize the control process, a novel hierarchical system is considered in which PID gains of primary, secondary, and tertiary controllers are tuned with metaheuristic moth-flame optimization to adapt to the variations. Matlab/Simulink simulations are performed to verify the efficiency of the proposed approach. The results highlight the superiority of the proposed method by utilizing process adaptive gains.