Distribution And Control Of Safety Parameters Of Current Return For Subways

At present,in order to relieve the traffic congestion,China's urban rail transit develops rapidly.At the same time,the safety of power supply during the system operation has gradually attracted people's attention.DC power supply system and running rails using as current return conductor are widely used in urban rail transit.In this process,stray current and rail potential are serious which have caused serious safety hazard for the underground system.How to ensure the safety of DC traction power system and avoid the hazards brought by the current return of traction current is of great significance.In this paper,the dynamic distribution and control methods of stray current and rail potential of urban rail transit are studied.The characteristics of DC traction power supply system for urban rail transit are studied.The main structure and the characteristics of related equipment are analyzed,especially the running rails,collection mats and ground with the drainage device and over voltage protection device.During the dynamic running of the trains,the force analysis of the train is carried out.Then the running equation of train is established,and the power-time characteristic and position-time characteristic are analyzed based on typical train parameters.Based on the dynamic running characteristics of trains,the dynamic distribution model of safety parameters of current return is studied in this paper.Firstly,static distribution model of stray current and rail potential is established with single train in one power section and the current return system with "Rail-Collection mats-Ground".The analysis of stray current and rail potential under specific train position and traction current can be reached.Secondly,based on the dynamic operation characteristics of the train,combined with the structure and parameters of the power supply system,a static power flow calculation model and a dynamic power flow analysis model are established.The dynamic power flow model of DC traction power supply system can get the current distribution of trains and traction stations under dynamic train operation,which can be combined with the static distribution model of stray current and rail potential to realize the dynamic distribution analysis of safety parameters of current return.Based on the dynamic distribution model of safety parameters of current return,the simulation of the dynamic distribution and control method of safety parameters of current return is carried out in this paper.Based on the typical parameters of power supply system and train,the simulation of power flow and the dynamic distribution of safety parameters of current return are carried out.At the same time,the simulation of the stray current and the rail potential under different starting threshold of the regenerative braking energy absorption device and the different running recoincidence of the train are carried out.Then the control methods of safety parameters of current return are analyzed.This paper contains 63 figures,12 tables,60 references.