Research On Harmonic Control Of High-speed Railway Traction Power Supply System

With the rapid development of high-speed railways,the electric traction load is gradually increasing,and the power quality problems brought by it are becoming more and more serious.The electric traction load is a high-power,non-linear load,so that the harmonics and reactive parts in the load current are very high,which not only affects the power system,but also causes damage to electrical equipment and the electric locomotive cannot operate normally.In addition,the presence of harmonics can also interfere with communication lines.Therefore,it is very necessary to conduct research on the harmonic problem of the high-speed railway traction power supply system.Firstly,through the harmonic analysis of the high-speed railway traction power supply system and the comparison of the existing harmonic control methods,this paper proposes a harmonic control scheme suitable for high-speed railway,and determines the active filter isolated by the coupled transformer.Hybrid filtering method in which the source filter is connected in series.Secondly,in order to make the hybrid active filter play better harmonic control effect,improve power quality,ensure the safety and stability of power system operation,and study its harmonic detection and control methods.Compared with several commonly used harmonic detection algorithms,the adaptive harmonic detection algorithm is selected and an improved variable step size LMS adaptive harmonic current detection algorithm is proposed.The simulation results show that the detection method is faster and more accurate,and it is suitable for the high-speed railway operating conditions in China.Furthermore,the control method of the hybrid active filter is determined,including the harmonic current tracking compensation control method on the AC side and the DC side inverter voltage stabilization control method.Finally,the entire hybrid active filter is modeled and applied to the actual operation of the CRH2 series EMU for simulation analysis.The results show that the proposed method can better track the compensation of harmonic current and control capacitor terminal voltage stability.Limiting the harmonic current and voltage to the range specified by the state can not only ensure the safety and reliability of the high-speed railway traction network itself,but also ensure the normal operation of the upper-level substation and the safety and stability of the entire power grid.This thesis includes 49 figures,6 tables and 77 references.