Control Strategy for Battery/Flywheel Hybrid Energy Storage in Electric Shipboard Microgrids

Integrated power system combines electrical power for both ship service and electric propulsion loads by forming a microgrid. In this article, a battery/flywheel hybrid energy storage system (HESS) is studied to mitigate load fluctuations in a shipboard microgrid. This article focuses on how to determine the reference operation state of the flywheel, which depends on both future power load and the power split between the battery and flywheel. Two control strategies are proposed—an optimization-based approach and a lookup-table-based approach. Case studies are performed in different sea conditions, and simulation results demonstrate that the proposed control strategies outperform baseline control strategies in terms of power fluctuation mitigation and HESS power-loss reduction. A comparison between the two proposed approaches is performed, where their performances are quantified, the advantages and disadvantages of each strategy are analyzed, and the cases where they are most applicable are highlighted.