Research On The Mechanism And Optimal Measures Of Rail Potential Abnormal Rise In DC Traction Power Supply System

With urban rail transit being expanding by leaps and bounds,the problem of power supply safety is becoming increasingly obvious.As urban rail transit generally adopts DC power supply and rail reflow,the rail potential problem is prominent during the reflow process,and the rail potential limiting device moves frequently,which seriously affects the normal operation of the system and endangers personal safety.The regularity of distribution and control method of rail potential need to be further clarified.For overcoming the problem above,this paper mainly studies the mechanism of abnormal increase of rail potential under the influence of power distribution in DC traction power supply system.Firstly,the parallel operation model of multi-train and multi-traction substation is studied.The working characteristics of traction substation with regenerative braking energy absorption device(READ),traction network and trains are analyzed,and the corresponding mathematical model are established.The working characteristics of rail potential limiting device(OVPD)and current drainage cabinet are analyzed,the mixed parameter model of the reflux system is established,and the parametric equivalent model is obtained by using the parameter correction method.The overall simulation model of multi-train and multi-traction substation is established.Based on the analysis of the force on the train during operation,the traction calculation model are established,and the distance,power and run chart of multi-train are obtained.Secondly,the parallel operation simulation of multi-train and multi-traction substation is studied.Based on the "chain network + node voltage method + Picard iterative algorithm",the static and dynamic power flow of DC traction power supply system is calculated.Combined with power flow distribution of power supply system,a calculation model of the dynamic distribution of rail potential is established.The simulation results show that the power flow algorithm and the dynamic distribution method of rail potential can accurately simulate the distribution of rail potential under various circumstances.At the same time,the simulation and field measurement verify that cross region power supply phenomenon of traction current is widely existed in DC traction power supply system.Then,the dynamic distribution of rail potential is studied.The theoretical model of cross region power supply of rail potential and traction current is established.Based on the network matrix method,the calculation method of power allocation between multi-traction substation and multi-train is established.The influence of power allocation between multiple nodes on rail potential at typical time is analyzed.The influence of changing the power distribution of the system,such as adjusting the startup threshold for READ,the run chart of trains and the distance between traction substations on rail potential,is studied.Combined with field measurement,the influence of power cross region allocation on rail potential is verified,and the influence of current drainage cabinet on the rail potential is analyzed.Finally,the optimization measures of the rail potential is studied.Taking the reduction of rail potential as the optimization goal,the system power distribution optimization model is established by using genetic algorithm.Simulation shows that this optimization algorithm is an efficient method to reduce rail potential.The paper has 45 pictures,14 tables,and 80 references.