Ocean Going Ship Route Optimization Based On Time-voyage-sea Weather Coupling

More than 80%of world trade is done by shipping which providing low-cost and reliable transportation measure.As the main body of international trade and transportation,promoting the transformation of the shipbuilding industry towards intelligent environmental protection and reducing ecological damage is in line with national economic development and security strategy.In recent years,Fuel prices have skyrocketed year by year,the International Maritime Organization successively introduced energy efficiency standards such as EEXI and CII,the European Union imposes a carbon tax on ship emissions and China proposed"dual carbon"plan fully demonstrate the urgency of conducting research on ship energy conservation and emission reduction.As one of the most effective energy-saving and emission reduction measures for operating ships,ship route optimization faces difficulties in matching loading meteorological data with ship sailing sea conditions,poor robustness of optimization algorithms,and outdated new optimization technologies.Therefore,the study on ocean-going ship route optimization with time-distance-weather coupling provides practical and feasible reference for cost reduction and efficiency increase,and is of great significance for the green and intelligent development of China’s shipbuilding industryThe models of ship route information,hydrostatic resistance,and added resistance are established for the ship complex energy consumption system,the hydrostatic resistance and speed through water is corrected considering the changes of seawater physical parameters and the influence of ocean currents and shallow water.In order to solve the loading efficiency and the matching degree by commonly loading methods,a dynamic real-time weather data loading method is proposed.Meanwhile,the evolution factor and speed update fractional order coefficient are introduced to enhance the global search ability and convergence accuracy of the optimization algorithm for solving the multi constraint nonlinear ship route optimization,the adaptive conversion fractional order PSO algorithm is improved,and the source program is developed.Finally,under the ship design speed,the main indicators and energy-saving effects of ship route optimization with different objective were analyzed.On the basis,considering the nonlinear and complex coupling relationship between route and speed synchronization optimization,the ocean-going ship route and speed co-optimization technology is developed to deeply explore the energy-saving,emission reduction,and economic benefits with different objective functions.Considering the complex sea conditions encountered by the ship during navigation,the ship hydrostatic resistance model with residual resistance correction factor,wave added resistance model with the joint action of short wave and long wave and sea wind added resistance model are established,and the friction resistance and the speed through water are corrected considering the changes of seawater temperature and salinity,the influence of ocean current speed and shallow water on the speed and the propeller efficiency in the actual navigation sea.On this basis,the prediction model of ship main engine power and the fuel oil consumption（FOC）under actual sailing condition is established.It is verified that the error of ship hydrostatic resistance model is less than±3.0%,and the calculated value of wave added resistance is in good agreement with the experimental values,especially for the fat large ships,the short wave added resistance model is essential.The application interface program for loading meteorological data from the European Centre for Medium-Range Weather Forecasts is developed,and the navigable sea area is initially delineated according to the ship voyage plan and wave information cloud chart.In addition,in view of the mismatch between the commonly used weather data loading methods and actual sailing conditions,a dynamic real-time weather data loading method is proposed to realize real-time weather data loading with estimated time of arrival of each waypoint as the loading time dimension,which ensures that the loaded weather accurately reflects the actual sailing sea conditions and provides support for the ship route optimization and ship route speed co-optimization considering the weather influence.To solve the shortages that the classical PSO algorithm solves the multi-constrained nonlinear optimization issue easily fall into local optimal solutions and poor stability,a evolution factor and velocity update fractional order coefficient are introduced to make the weights and acceleration coefficients adaptively transform with the evolution state to enhance the global search ability and local convergence stability under the premise of ensuring the optimization efficiency.The improved algorithm can converge to the optimal solution after about 500 iterations,especially in solving multi-peak,multi-dimensional and multi-modal optimization problems including exponential functions and trigonometric functions,etc.,the improved algorithm outperforms the classical or other PSO algorithms.The route optimization of 300000 DWT VLCC with single objective of min.（FOC）,min.sailing time（ETS）and min.operation cost（COE）,and bi-objective of FOC and ETS was conducted under the design speed.Compared with the actual sailing data,the optimization results show that the FOC per nautical mile is reduced by 16.66%,12.71%,15.93%and13.15%,and the ETS is reduced by-0.75%,6.60%,4.87%and 5.48%with the four optimization objectives.Meanwhile,the effect of the constraints on the optimization results was verified with the min.FOC objective.The comparison reveals that the FOC is reduced by1.64%for the missing geographical constraint than the complete constraint;the optimized route has an unreasonable result of crossing land.In addition,the influence of fuel price on the route optimization results is also explored.When the fuel price is high,route optimization with min.FOC objective is more conducive to energy saving and emission reduction,the min.ETS is recommended as the optimization objective conversely.Considering that the ship energy efficiency operation index is affected by route and speed,the route optimization of fixed ship speed,speed optimization of a given route and real-time loading of meteorological data are organically integrated,and the ocean-going ship route and speed co-optimization technology with dynamic real-time loading of meteorological data is developed.Compared with the single route optimization,the min.FOC objective reduces FOC per nautical mile by 0.82%,the min.ETS objective shortens sailing time per nautical mile by 3.73%,and the min.COE objective saves cost per nautical mile by 0.12%.In addition,regardless of whether the route single optimization or the route-speed co-optimization,the min.FOC objective optimization has the min.CO₂ emission per transport capability,the min.ETS objective optimization has the highest operating cost,and the other two optimization objectives are in between.The difference is that the CO₂ emission of the route-speed co-optimization is 1.05 times of the actual sailing with the min.ETS objective,which indicates that the pursuit of quick sailing inevitably leads to the increase of FOC and CO₂ emission as well as the increase of COE.The realization of route optimization and route-speed co-optimization considering sea weather conditions effects can provide strong technical support for ocean-going ship to reduce energy efficiency operation index.