A first approach for the energy management system in DC micro-grids with integrated RES of smart ships

This paper proposes an Energy Management System (EMS) of the electrical plant of a yatch with a DC micro-grid structure. Such an EMS has as target function the reduction of the DE fuel consumption and correspondingly of the related polluting emission. A complete dynamic model of the electric plant of a yacht has been presented. In particular, assumed that the main electrical generator of the ship is moved by a diesel engine, a DC smart-grid structure is speculated, where each Renewable Energy Source (RES) can supply power to the ship load, when available. The system is integrated with a wind generation system, a photovoltaic generation system and a fuel-cell system of the PEM (Proton Exchange Membrane) type. The entire dynamic model has been developed by the authors in symbolic form in Matlab®-Simulink® environment. The proposed DC smart-grid model with integrated RESs has been tested on a real mission profile, considering real irradiations and wind speed profiles taken in locations close to the ship route. The proposed EMS is based on the choice of the optimal working speed of the DE corresponding to its minimum fuel consumption and corresponding polluting emission. The algorithm is integrated with a routine checking the stability of the generator at each potential working point. Furthermore, DC line voltage stability and DE speed reference will be further analyzed. Results will show that the fuel consumption optimization strategy permits the ship to reduce the fuel consumption on a daily scale of about 18%.