Tri-objective optimal design of a hybrid electric propulsion system for a polar mini-cruise ship

Abstract

The environmental impact, economic considerations, and passenger comfort of hybrid electric propulsion systems (HEPSs) are significantly influenced by the design phase. However, a design method solely focused on minimizing annual fuel consumption may inadvertently lead to increased life-cycle cost and decreased annual pure-electric sailing time. To address this issue, this paper presents a tri-objective optimization design method to achieve an optimal trade-off among the objectives for a polar mini-cruise ship. First, a scalable mathematical model is established for a hybrid diesel engines/batteries/shore power propulsion system. Then, a refined, rule-based energy management strategy is developed to control the power flow among energy sources. Next, a tri-objective optimization model with detailed descriptions of objectives, variables, constraints, and method is formulated. Finally, the performances of three optimal designs, obtained through tri-objective optimization, single-objective optimization, and conventional heuristics, are compared through simulations based on a typical real-world navigation case. The results highlight the clear advantages of the proposed method over the other two methods. Furthermore, sensitivity analysis underscores that the parameters of the diesel engine, battery, and gear ratio exert a greater impact on HEPS performances than other factors.