| Nowadays,direct current(DC)traction power systems are widely used in multi-train subway systems.During the dynamic operation of multiple trains,the different distribution of regenerative braking power affects the energy consumption and power supply safety of the system.The energy consumption of the multi-train subway system is huge,and how to make the system energy saving has always been a research hotspot at home and abroad.In addition,excessive rail potential and stray current often appear in the lines,which will not only threaten the personal safety of passengers and the operation safety of railside equipment,but also cause serious electrochemical corrosion to the buried metal pipelines around the line.Therefore,it is urgent to study the optimization method of output characteristics of the traction substation and the timetable parameters to realize the energy saving and power supply safety of the system.The main research contents of this article are as follows:Firstly,this thesis studies the dynamic operation characteristics of the multi-train DC traction power system.The structure and characteristics of the DC traction power system under parallel operation of multiple trains and multiple stations are analyzed,including traction substations,trains,catenary,reflux safety protection devices,etc.Based on force analysis and motion equation of a train,traction calculation method is established to realize the calculation and analysis of train operation parameters;the distribution characteristics of reflux safety parameters and the characteristics of energy consumption during dynamic operation of multiple trains are clarified.Secondly,the fast power flow calculation method of the system under the dynamic operation of multiple traction stations and multiple trains is studied.The dynamic operation calculation model of the vehicle-network coupling system based on the parallel multi-conductor structure is proposed,and the model equivalence and parameter correction method of the mixed-parameter reflux system including distributed parameters and lumped parameters are studied.Based on the chain circuit model,the power flow calculation matrix of the system is established to realize the fast power flow calculation under the parallel operation of multiple traction stations and multiple trains.At the same time,a calculation method of regenerative braking power distribution is established to track the power distribution among multiple nodes.Thirdly,according to the energy-consumption type DC traction power system that is widely used at present,the calculation method of the rail potential of the whole line with the regenerative braking power transferring over zones is analyzed,and the influence of the power transferring over zones on the reflux safety parameters is clarified.In order to control the maximum rail potential of the system,a multi-train timetable optimization method based on an improved Seeker Optimization Algorithm is proposed,and the adjustment of power distribution is realized by optimizing the train diagram to limit the maximum rail potential of the system.Furthermore,considering the influence of power distribution of system on energy consumption,a Non-dominated Sorting Genetic Algorithm based on Kernel Density Estimation is proposed to solve the dual-objective optimization problem of energy saving and power supply safety,and realize coordinated control of energy saving and power supply safety during the operation of multiple trains.Finally,in view of the controllable output characteristics of the bidirectional converter unit of the new flexible DC traction power system,a triple-objective optimization model of the maximum rail potential,energy consumption and maximum traction current of the flexible DC traction power supply system is established.The enhanced Non-dominated Sorting Genetic Algorithm Ⅲ is proposed to solve the triple-objective optimization problem,and the optimization of the output characteristics of the bidirectional converter unit and the train diagram of the flexible DC traction power system is realized.To sum up,this thesis conducts a series of researches on the fast power flow calculation method under the train-network coupling subway system,and the energy saving and power supply safety of the DC traction power system.The multi-objective optimization operation schemes are proposed and the energy saving and safe operation of the system is realized. |
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