Research On Electric Vehicle Routing Problem For Cold Chain Logistics With Active Variable Speed

With the rapid development of China's economy,the quality of life of residents has been significantly improved,which provides a driving force for the development of cold chain product market,and the scale of cold chain logistics market has expanded dramatically.Compared with normal temperature products,cold chain products are perishable and vulnerable.The distribution of cold chain products in low temperature environment will be accompanied by more energy consumption and exhaust emissions.It has become the future development trend that electric logistics vehicles replace traditional fuel vehicles to undertake the task of cold chain logistics distribution,which can further promote the development of cold chain logistics to green and low carbon.However,due to the problems of short endurance mileage,long charging time and insufficient charging facilities,how to make full use of electric energy to complete as many distribution tasks as possible,and how to reduce the consumption of electric energy as much as possible on the basis of completing distribution tasks,so as to save more costs,has become a subject worthy of study.Considering that the energy consumption of electric vehicles is related to the driving speed of vehicles,therefore,based on the actual speed range of the road,the active optimization of the driving speed will help to reduce the energy consumption and distribution cost of electric cold chain logistics vehicles.Based on this,this paper studies the cold chain vehicle routing of electric vehicles from the perspective of variable speed.The research work is as follows:(1)Summarize and analyze the research status of the electric vehicle routing problem,cold chain vehicle routing problem,electric vehicle routing problem for cold chain,pollution vehicle routing problem at home and abroad,and discuss the necessity and feasibility of introducing the variable speed into the optimization of the electric vehicle logistics distribution for cold chain.On this basis,active transmission is applied to the field of optimized distribution of electric cold chain logistics for the first time,and the electric vehicle routing problem for cold chain logistics with variable speed and time window(VEVRPTW-CC)is proposed.(2)Establish the mathematical model of VEVRPTW-CC.Based on the energy consumption model of electric vehicle with variable driving speed,the objective function of minimum total distribution cost composed of vehicle use cost,power cost,refrigeration cost and time penalty cost is established.And the mathematical model of VEVRPTW-CC is established considering vehicle capacity,electric quantity,vehicle speed,time window and other constraints.(3)Design a hybrid ant colony algorithm for VEVRPTW-CC.Firstly,the basic ant colony algorithm is improved.According to the characteristics of VEVRPTW-CC,the state transition rule,path construction process and pheromone update strategy are designed,focusing on the optimization of vehicle speed in each road section.Secondly,in order to improve the search performance of the algorithm,six kinds of local optimization are designed,including node exchange,time optimization,speed optimization and charging station optimization.The initial solution of ant colony algorithm is further optimized by using adaptive selection mechanism and simulated annealing framework.(4)Analyze experimental results.The benchmark database of VEVRPTW-CC is constructed,and the experiments of parameter setting,algorithm performance,constant speed and variable speed are carried out.Parameter setting experiment is used to optimize algorithm parameters.The algorithm performance experiment is used to compare and optimize each local optimization operator and selection mechanism to verify the performance of the hybrid ant colony algorithm.Constant speed and variable speed experiments are used to compare the effects of four kinds of constant speed and variable speed,and verify the value of variable speed for evrptw-cc problem.