Research And Simulation On Traction Power Supply System Of Electrified Railway

With the rapid development of China’s electrified railway,the require to safety and reliability of railway traction power supply system is becoming higher and higher.So it is very important to build a digital dynamic simulation system for railway traction power supply system based on the deep study,analysis and calculation of traction power supply system of electrified railway.The digital dynamic simulation system is a system which constructs a mathematical model of railway traction substation system,uses the KPF9 test platform to undertake the model,connects relevant power source and output the measured voltage and current.This paper aims to construct the digital dynamic simulation system for railway traction substation system mathematical model.By comparing the actual fault data with the simulation of the model,it is proved that the model can reflect the actual fault of power supply system.This study lays the foundation for the construction of digital dynamic simulation system of railway traction power supply system.It is of positive significance to improve the safe operation of railway traction power supply system.Firstly,the principle of traction power supply system is analyzed in detail,the equivalent model is made,and the relevant parameters in normal operation is reasonably deduced.As for the AT network with and without guard line,end-parallel double line AT network and all-parallel AT traction network,the current distribution,voltage loss and short-circuit impedance are analyzed and respectively established the calculating formulas for parameters.In addition,the parameters of the power supply,the traction transformer and the AT traction network are calculated in the normal operation state of the power supply system,and then the relatively reasonable parameters of traction power supply system are obtained.By using Matlab/simulink,the model of traction power supply system is made,and the no-load test is carried out to prove that it can be used and more consistent with the field situation.Secondly,this paper analyzes the electric locomotive thoroughly,and focuses on the rectifier principle and rectifier circuit of the representative AC-DC type electric locomotive SS4.By means of Matlab/simulink,the simulation model of electric locomotive SS4 has been made to simulate a normal operation,which suppresses its harmonic content in an objective way.The paper also analyzes the inverter circuit and tractor motor principle of the representative AC-DC-AC type electric locomotive HXD3,especially focusing on the inverter circuit transfer vector control technology.The electric locomotive HXD3 model is also built by Matlab/simulink.By testing its output speed,torque,current and flux trajectory,it proves effective and reaching the steady state in advance,with very good robustness.Thirdly,based on the mathematical models of the railway traction substation system,the railway traction substation system AC-DC load of main circuit and the railway traction substation system AC-DC-AC load of main circuit,this paper does the relevant calculation and simulation analysis of current and voltage in no-load condition,load condition and fault condition.By comparing the result of simulation with the actual fault parameters,it confirms that the mathematical model of the railway traction substation system is effective.