Research On Optimization Of Grid Connection Strategy For Large Cruise Ship Generator Set

The grid connection strategy of generator sets is an important part of ship power management system.Electric propulsion ships require proper configuration of generator sets and loads to ensure safe,stable,and energy-efficient operation.Currently,most electric propulsion ships utilize sag control to distribute the load to parallel gensets,with on-grid gensets proportionally distributed to the ship’s electric load based on their rated capacity.However,with the emergence of electronic governors and the basic principle of power distribution for parallelrunning gensets,non-uniform load distribution can enable parallel gensets to operate at different output powers on the same grid compared to uniform load distribution by sag control.This paper proposes a method of non-uniform load distribution for genset load distribution to improve the parameters of the on-grid genset operation process.Using a large Vista-class cruise ship as an example,this paper selects and quantifies three optimization objectives for the genset grid connection strategy based on the ship’s characteristics: fuel consumption,NOx emission,and power regulation time.NSGA-II is used to optimize the grid connection strategy of the generator set with three objectives,and the noninferior solution set of the grid connection strategy of the generator set is derived.The objective weights are determined using the entropy weighting method,and the subjective weights are determined by the hierarchical analysis method and coupled to obtain the comprehensive weights.Finally,the TOPSIS decision analysis method is used to select and obtain the integrated optimal cruise ship genset grid connection strategy.To verify whether the optimal cruise ship genset scheduling scheme can meet the operation standard of the cruise ship power system,this paper establishes a model of each subsystem of the cruise ship power system according to the power system principle.The time of genset phase synchronization process before grid connection is optimized and reduced,and a simulation model of a large cruise ship power propulsion system is established and verified.This model simulates operating conditions such as dual-engine grid connection,heavy load start,and load disturbance.Finally,by simulating the operation of the cruise ship power system,each parameter of the power system meets all relevant requirements.This paper proposes a grid connection strategy for large cruise generating units based on multiobjective optimization,selects and quantifies three optimization objectives in the scheduling process of ship generating units,develops a power distribution scheme for parallel generating units with uneven load distribution,and selects the optimal grid connection strategy for cruise generating unit scheduling through multi-objective genetic algorithm and decision analysis method.Compared with the droop control scheme,this strategy reduces the fuel consumption by 0.94g/k Wh on average,And the economic speed drops by 3.68 g/k Wh,NOx emissions decreased by 1.293 g/k Wh,with a decrease of 27%.And the power system of the cruise ship was simulated to verify the rationality of the optimization strategy in this paper.The research results can provide reference for the control and optimization of large cruise electric propulsion systems.