Stability-Aware Dynamic Load-Shaping Energy Management Strategy for Improving Diesel Generator Operational Stability in Hybrid Shipboard Power Systems

This study proposes a stability-aware load-shaping energy management system (EMS) for a hybrid electric shipboard power system. The proposed EMS uses the energy storage system (ESS) as a dynamic load-shaping buffer to reduce active diesel-generator (DG) low-load exposure and electrical power fluctuations. A supervisory reference-generation procedure integrating low-pass filtering, ESS state-of-charge (SOC) compensation, DG ramp-rate limiting, residual-power calculation, and explicit power and SOC constraints was implemented on a real-time controller. Comparative experiments were conducted on an MW-class platform comprising one active 600 kW DG, a 400 kW/400 kWh ESS, two 450 kW propulsion-load channels, and a 100 kW service-load channel connected to a 750 V DC bus. The second installed DG remained offline during all comparative experiments. Under a common one-hour ship-load profile, the proposed EMS reduced the low-load exposure ratio from 0.1320 to 0.00139, the DG power variance from 3.06 × 104 to 1.37 × 104 kW2, and the mean DG ramp rate from 13.8 to 0.776 kW/s relative to the rule-based EMS. These values correspond to reductions of approximately 98.9%, 55.2%, and 94.4%, respectively. After terminal-SOC correction, the BSFC-map-estimated equivalent fuel consumption decreased from 90.4 to 88.2 kg. Experimental parameter-sensitivity tests demonstrated the trade-offs among DG power smoothing, low-load exposure, SOC regulation, and ESS participation. A supplementary offline Monte Carlo analysis further indicated that the principal comparative benefits were maintained under bounded variations in load magnitude and fluctuation amplitude. The results demonstrate that the proposed EMS improves supervisory DG loading quality while maintaining the ESS within its prescribed power and SOC limits.