Modeling, control and safety of hybrid energy storage systems in microgrids

The rapid growth of renewable energy sources (RESs) has introduced significant uncertainty and instability to the operation of smart microgrids. To address these challenges, energy storage systems (ESSs) have become essential, as they can effectively mitigate the impact of the fluctuations of RESs. However, ESSs consisting of single-type energy storage devices face limitations in meeting the various requirements of microgrid applications. A hybrid energy storage system (HESS) that integrates multiple types of ESSs offers a popular solution by exploiting their complementary characteristics. This article provides a comprehensive review of the state-of-the-art technologies of HESSs, covering their types, modeling methods, control strategies, and particularly, the safety considerations that have often been overlooked in the existing review papers. The pros and cons of the existing works across these four dimensions are also critically analyzed. Finally, future trends and potential directions are highlighted to carry out further research and the practical implementation of HESS technologies.