Research On The Distribution Characteristics And Restriction Methods Of Safety Parameters In DC Traction Power Reflux System

DC traction power system are used in most urban rail transit systems,which use rail reflux and generate stray currents and rail potential during their dynamic operation,which can cause various accidents,such as pipeline corrosion leakage accidents caused by stray current corrosion and power accidents caused by frequent operation of the over voltage protection device occur frequently.In this paper,stray current and rail potential are used as safety parameters of reflux,and their distribution laws and limiting measures are studied,which is of great significance to the safety of DC traction power system.This paper analyzes the composition and characteristics of the DC traction power system,and establishes the equivalent model of the DC traction power supply system.Based on the analysis of the train force,the traction operation model of the train is established,and the influence of the train operation parameters on the power parameters is studied.On the basis of establishing the equivalent model of traction power system and combining the calculation results of train traction,this paper studies the establishment methods of the system power flow calculation model at a certain moment and the dynamic calculation of power parameters model is completed based on the power flow calculation model.The equivalent model of the reflux system and its microelement equivalent resistance model are established.Based on the above models,this paper analyzes the current relationship between the traveling rail,the drainage network and the buried metal,as well as the voltage relationship between the traveling rail,the drainage network and the buried metal.At the same time,the current relationship between the substation and the train,as well as the relationship between the braking train and the traction train is analyzed.Combined with the above analysis,the establishment of a static distribution model of the reflux safety parameters is completed;Based on the static distribution model and the dynamic calculation of power parameters,a dynamic distribution model of reflux safety parameters is established.Based on the above power flow calculation model and reflux safety parameter distribution model,the variation of power parameters of DC traction power system is simulated and analyzed.The over zone feeding transmission law of traction current in different working conditions of trains is expounded and verified by field tests.The distribution of reflux safety parameters under different operating conditions of trains is simulated and analyzed,the relationship between over zone feeding and reflux safety parameters is expounded.At the same time,the relationship between reflux safety parameters and system parameters,train running overlap ratio and READ start threshold is studied.On the basis of simulation analysis,test data of the field is analyzed to verify the influence of over zone feeding on the reflux safety parameters.On the basis of summarizing the influencing factors of reflux safety parameters,the limiting methods the reflux safety parameters are proposed.This paper mainly studied the method about how to optimize stopping time of train and the selection of READ start threshold,which feasibility is verified by simulations.