Harmonic Assessment Of Traction Power Supply System And EMU In Electrified Railways

With the fast development of electrified railways in China,thousands of electric locomotives have been put into operation in Chinese railway network every day.Due to the special topology of the traction power supply system(TPSS)and the high-power,non-linear and multi-condition features of EMUs,the traction load is featured as stochastic,unbalanced,and concentrated in some points.The power quality of TPSS and EMU on the electrified railways has gained more attention.Therefore,this paper mainly focus on the harmonic assessment of the TPSS and EMU.And the main work of this paper is as follows:Firstly,the traction power supply system is analyzed in this paper.The structure of TPSS and the function of each part is systematically introduced.Five types of traction transformers is analyzed and their negative sequence calculation equations are derived.Several supply mode of electric locomotives are analyzed and their advantages and disadvantages are evaluated,respectively.Secondly,the high speed EMU is analyzed and modeled in this paper.The traction drive system structure of the high speed EMU is analyzed,as well as the detailed circuit model of the traction rectifier and inverter.The control strategy and principle applied to the traction rectifier is analyzed.Based on the software of Matlab/Simulink,the EMU is modeled and its harmonic output characteristics is analyzed under different power output.Thirdly,the harmonic of high speed EMU is analyzed in this paper.Based on large amount of field data of running EMU,the traction power is calculated and the harmonic output of the EMU is analyzed under different working conditions.And the harmonic pollution is assessed.Lastly,the harmonic of TPSS is analyzed in this paper.Based on the field data of the traction substation for a whole day,the traction power of the substation is calculated.The harmonic of the substation in a whole day is assessed,including the statistical harmonic spectrum of current and voltage,the THD of voltage along with time,and the harmonic content of each order harmonic.