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Optimal scheduling of diesel generators in offshore support vessels to minimize fuel consumption

Abstract:

This paper presents optimal generation scheduling for minimization of fuel consumption (FC) in an offshore support vessel with a dynamic positioning system and diesel generator (DG) sets of 8000 kW total capacity. FC is analyzed for equal load sharing among equal capacity DGs, optimal load sharing among equal capacity DGs, and optimal load sharing among unequal capacity DGs. Due to nonlinear specific FC (SFC) curves of the diesel engines, a Genetic Algorithm is used for optimal load sharing. The SFC-vs-load relationship obtained from Brake SFC (BSFC) map of the diesel engines is characterized using a cubic spline interpolation. A solution to the problem is attained by comparing yearly fuel consumption in the three cases for the load profile of target vessel. This method can be applied to any vessel equipped with multiple generating units. A vessel with proper selection of DG capacities and closed bus-tie can achieve maximum fuel savings; however, when deciding the DG capacity and load scheduling, it is necessary to consider fuel consumption alongside concerns such as optimizing exhaust emissions after-treatment, ensuring adequate power availability for essential services, and scheduling engine maintenance.