Research On Energy Saving And Rail Potential Suppression Technology Of Subway

Urban rail transit is a fast and low-carbon mode of public transport,and its rapid development is accompanied by the rapid rise of traction energy consumption.Dc traction power supply system is widely used in urban rail transit,and steel rail is used as the return path of electric energy.In the process of return flow,abnormal rise of rail potential will occur,which will affect the normal operation of equipment and threaten the safety of passengers.In this thesis,the energy-saving speed curve of the train is taken as the research object to reduce traction energy consumption,the DC traction power supply system is modeled and the simulation calculation method of reflux parameters is designed.On this basis,the comprehensive optimization model of train schedule is established to suppress the rail potential of the whole line,and at the same time,the energy-saving optimization of the subway and the abnormal treatment of reflux parameters of the whole line are taken into account.Firstly,this thesis establishes the train dynamics model,deduces the optimal energy saving strategy for trains,and takes into account the train stopping accuracy,passenger comfort and punctuality constraints on the basis of considering the speed limit and slope of the line.By using the combination of traction,idle running and braking conditions,a multi-objective optimization model of energy consumption and interval running time is established with the working condition transition point and working condition transition sequence as decision variables.The non-dominated sorting genetic algorithm is introduced,and Circle chaotic mapping initialization is incorporated into the algorithm.The crossover operator is improved,and the adaptive crossover mutation probability is adopted.Finally,the improved algorithm is used to solve the model and verified on the data of a domestic subway line.The simulation results show that the optimization method designed in this thesis can effectively reduce the interval traction energy consumption,and the total energy-saving efficiency of a single train line is 7.96%.Secondly,the simulation model of reflux parameters under complex operating conditions of multiple trains running in parallel was established.The locations of trains and traction substations were regarded as sections.The three-layer structure of "rail,drain network and ground network" was adopted for the reflux part,and the mixed parameter model was converted into a centralized parameter model according to the boundary conditions.According to the characteristics of parallel multi-conductor system,the nodal voltage equation under the centralized parameter model is derived,and the Picard iteration principle is introduced to accelerate the reflux parameter solving speed.On the basis of the trains running in accordance with the energy-saving speed curve mentioned above,the simulation analysis of the reflux parameters of the whole line was carried out,and the difference of the distribution of reflux parameters under the energy-saving condition in this thesis and the three-stage "tractor-cruisebraking" rapid operation strategy commonly used in existing studies was compared.The results verified the effectiveness of the simulation calculation method of reflux parameters in this thesis.The simulation results show that the backflow parameters of the circuit increase abnormally.Finally,the influence of different factors on the size and distribution of rail potential is simulated and analyzed.The common rail potential suppression device and drain device will produce great side effects when put into operation,which can not effectively inhibit the rail potential of the whole line.Under complex conditions of multiple trains running side by side,power coincidence between trains will cause longdistance transmission of traction current across the power supply interval,which will lead to abnormal increase of reflux parameters.In this thesis,a comprehensive optimization method of train schedule based on improved grey Wolf algorithm is adopted to reduce rail potential of the whole line,and the stopping time of upstream and downstream trains and departure interval between trains are adjusted at the same time.Finally,the rail potential amplitude of the whole line is suppressed below 74.1V by simulation,which proves the effectiveness of the proposed rail potential suppression method.