Design and Control of an Energy Storage System for Hybrid Renewable Energy Systems

Integration of a storage system into hybrid renewable energy systems is investigated in this paper. The storage system features a bidirectional Buck-Boost converter connected with a Lead-Acid battery pack. The converter operates in Buck mode for charging and Boost mode for discharging the batteries. The proposed control strategy aims to regulate the current delivered or consumed by the batteries, ensuring a constant DC bus voltage regulation regardless the system operation mode. This is achieved through the implementation of two cascaded regulation loops. Key innovations include precise design of the converter and effective regulator synthesis through transfer function modeling, addressing inherent challenges posed by nonlinear and variable converter structures. Simulation tests validate the system robustness, demonstrating its capability to meet energy demands and maintain voltage stability under various operational conditions.