Large-Signal Stability Analysis of All-Electric Ships With Integrated Energy Storage Systems

All-electric ships (AESs) with efficient direct current (DC) shipboard microgrids become a significant means to reduce carbon emissions. Large-scale energy storage systems (ESSs) can provide sufficient operating flexibility to mitigate power fluctuations for the shipboard microgrid system. However, the power supply capability of the shipboard battery can significantly vary during actual operation, potentially causing voltage instability in the shipboard microgrid system. This article proposes a large-signal stability analysis method that considers battery dynamics for the shipboard microgrid system. Firstly, a novel full-order shipboard microgrid system model is proposed to comprehensively capture system electrodynamics. Then, conservative stability conditions with battery peak current constraints are derived. Based on these conditions, the influences of battery dynamics on the large-signal stability of the system are revealed for the first time. The results show that the domain of attraction (DOA) of the system varies significantly with different battery states. To verify these influences in the application, a general model predictive control (MPC) method that considers battery dynamics is adopted. The simulation results demonstrate that the direct current (DC) voltage sags can be reduced by 11.27%, and the battery can always operate within a healthy power range.