Model predictive control-based energy management strategy for ocean-going ship direct current microgrid considering waste heat utilization

The traditional ship energy systems face challenges such as poor system stability and difficulty in coordinating multiple energy devices. To address these issues, an innovative ship direct current (DC) microgrid system by integrating waste heat recovery and hybrid energy storage system (HESS) is proposed. First, dynamic models of key subsystems (diesel generator, lithium battery, supercapacitor, and organic Rankine cycle (ORC)) are established, and their accuracy is verified. Subsequently, the dynamic response characteristics of ORC's key parameters under step changes in exhaust gas characteristics and superheat degree are explored. Finally, a hierarchical energy management strategy (EMS) incorporating a first-order low-pass filter, model predictive control, and proportional integral controller is proposed, and its effectiveness and superiority in stabilizing microgrid operation under complex operating conditions are verified. The findings reveal that, after integrating the ORC and HESS, the diesel generator can reduce power output, fuel consumption, and CO2 emissions by 6.06 × 106 kW, 1741.05 kL, and 5144.94 t, respectively, over the course of one year, which makes the ship's fuel consumption reduced by 6.47 %. Additionally, compared to the traditional PI control strategy, the proposed EMS demonstrates significant advantages in suppressing bus voltage fluctuations, with a maximum fluctuation and tracking error of 7.89 V and 1.05 %.