Control Strategy And Application Of Regenerative Braking Force For Heavy Haul Trains

With the development of heavy haul transport in China and the operation of 20,000 t heavy haul trains,the transport capacity is increasing,but the longitudinal dynamics problems are becoming more and more serious at the same time.The problem of large coupler force often occurs in heavy haul combined trains after braking and release,and the excessive coupler force may cause train derailment and coupler separation,threatening the security of train operation,and the control strategy of locomotive regenerative braking force is particularly important to the operation quality of the train.Therefore,it is significant to study the control strategy of locomotive regenerative braking force after the releasing of 20,000 t heavy haul train and propose the control strategy which can reduce the coupler force after train releasing and explore the causes of the train accident in order to avoid the recurrence of the accident.By using the Train Air Brake and Longitudinal Dynamics Simulation System(TABLDSS),the asynchronous and synchronous operation strategy of locomotive regenerative braking force after 20,000 t heavy haul train’s releasing on the flat straight line was studied,and obtained the asynchronous and synchronous operation strategy of locomotive regenerative braking force which is beneficial to the reduction of train coupler force after train releasing.Two train accidents occurred on the actual line of the heavy haul train were investigated,the process of the train accident was simulated,and the causes of the train accident and the characteristics of the coupler force were analyzed.By making use of the influence mechanism of locomotive regenerative braking force on coupler force,the improvement operation method of accident train was proposed,the coupler force and the possibility of train accident were reduced.The simulation results showed that,the movement trend of first tensile and then compressed will occur after the train is released,and when the train is released,the maximum tensile coupler force can be reduced by increasing the regenerative braking force of the main locomotive,reducing the regenerative braking force of the slave locomotive and synchronously increasing the regenerative braking force of the locomotive,and the maximum tensile coupler force can also be reduced by release the slave control locomotive in advance.The 4 control modes reduce the maximum tensile coupler force by 21.3%,12.7%,19.0% and 21.6%.After the occurrence of the tensile coupler force,the train will produce a compressed coupler force,which can be reduced by reducing the main locomotive regenerative braking force or slave locomotive regenerative braking force and synchronously reducing the locomotive regenerative braking force.The maximum compressed coupler force after train releasing can also be reduced by increasing the main locomotive regenerative braking force or synchronously increasing the locomotive regenerative braking force to weaken the train tension.The 4 control modes reduce the maximum compressed coupler force by 51.2%,15.9%,55.1% and 13.6%.The coupler separation accident of a 20,000 t train on a heavy haul line is simulated and analyzed,and it is concluded that the important cause of the coupler separation is due to the 2 mutant tensile coupler forces during the train releasing.According to the strategy in chapter 1,a control improvement scheme is proposed,which eliminates the second mutant force and reduces the maximum tensile coupler force of the train.After the train is released,the maximum tensile force is reduced by 18.2%.In view of a heavy haul train derailment accident on a heavy haul line,the process of train derailment is simulated by using TABLDSS,and it is found out that the main cause of the train derailment is the mutant compressed coupler force produced in the compression process after the train is released.The operation strategies for reducing the maximum compressed coupler force and mutant force are proposed,in which the maximum coupler force and mutant force are reduced by 42.5% and 62.8%.The operation strategies reduced the risk of train accidents.