Hierarchical robust shipboard hybrid energy storage sizing with three-layer power allocation

Hybrid energy storage systems (HESSs) have gradually been viewed as essential energy/power buffers to balance the generation and load sides of fully electrified ships. To resolve the balance issue of HESS under multiple power resources, that is, shipboard diesel generators and fuel cells (FCs), this study proposes a robust sizing method implemented with a power allocation strategy. The proposed method is hierarchically formulated as two sequential sub-problems: (1) a robust programming to determine the power/energy capacities of HESS under the maximal power demand scenario and (2) a control framework to fulfil the power allocation under multiple power resources. A ship case with one diesel engine and one FC is studied to show the validity of the proposed method. The simulation results show that the integration of HESS facilitates the power supply of critical propulsion loads. Compared with no HESS, HESS integration can reduce the deviation of direct current bus voltage sag by 56% and reduce the power fluctuations of the main engine and FC by 7.3% and 55.9%, respectively.