Studies Of Optimal Operation Algorithm For Freight Train Based On Expert System

With the enlarging scale of railway transportation system in China,railway freight transportation becoming increasingly busy.So the energy consumption has been a matter of concern.Studying the optimal operation algorithm of a freight train,generating the energy-efficient operation speed profile and manipulation levels for train drivers under the given trip time will effectively reduce the train energy consumption,improve the efficiency of railway freight transportation and reduce the workload of train drivers.Based on the summarized rules in this thesis with respect to energy-saving,smooth and rational driving,the priorities between these rules are analyzed and coordinated.Then the basic rule set which can be used to optimize the operation of a freight train is built.After proposing the local energy minimization function,this thesis designs the judgment rule set of optimal operation mode switching point.Based on these two rule sets,the knowledge base is built and an expert system is constructed.Then an energy-efficient driving algorithm based on the expert system is designed,which can be used to generate speed profiles and manipulation levels under safety,punctuality,smooth and other rational constraints.Firstly,according to the train traction calculation,the operation model of freight train is built.Then a mathematical model for the optimal energy-efficient train control problem is described.With the application of the maximum principle,the set of optimal operation mode and the principles of operation mode switching are obtained.Secondly,the method of line section division is determined.Then based on theoretical results of the optimal energy-efficient train control problem,the rules of optimal energy-efficient operation under diffierent line conditions are discussed.Combining the cause of longitudinal impact in a freight train with the smooth-handling experience of good drivers,the smooth operation rules of freight trains is summarized.On the basis of the operational constraints of electrical locomotives,we obtain the rules of rational handling.After analyzing and coordinating the priorities of these rules,this thesis builds the basic rule set which can be used to optimize the operation of electrical freight train.Then,based on the relationship between local energy consumption and running time,this thesis proposes the general form of local energy minimization function with a time-weighted coefficient and gives the coefficient.On analyzing the solution space of optimal operation mode switching point and the concrete form of the local energy minimization function under different line conditions,the judgment rule set of optimal operation mode switching point is designed.Finally,based on these two rule sets,this thesis builds the expert system with the establishment of knowledge base.Then the optimal operation algorithm on the basis of the expert system is proposed for freight train.In order to verify the correctness of this algorithm,simulation is conducted on a virtual line and an actual line in MATLAB environment.Simulation results show this optimal operation algorithm based on expert system for freight train has a good performance on train operation.