Research On Power Quality Control System Of Electrified Railway Based On V/v Transformer

With the rapid development of China's electrified railway,the use of high-speed and high-power electric locomotives to the traction power supply system to bring the negative sequence,reactive and harmonic problems become increasingly prominent.In order to effectively control the power quality of electrified railway,scholars put forward a variety of comprehensive management plan,this thesis presents a V/v transformer based electromechanical power quality control system(V/v-Railway Power Quality Manage System,V/v-RPQMS),the device through the multi-winding isolation transformer cascade multiple back-to-back converter,effectively improve the device's compensation capacity,reduce the converter itself generated harmonics,the face of the rapid development of high-speed railway,application promotion potential.The specific contents of this thesis are as follows:Firstly,this thesis introduces the characteristics of the electrified railway and the quality problems of the power quality.The influences caused by these power quality problems and the common control measures are introduced.The converter control method at home and abroad is briefly introduced,and the research status quo of the DC voltage ripple suppression methods.Then,the topology of V/v-RPQMS and the various components are expounded.At the same time,the working principle of V/v-RPQMS is expounded,the principle of V/v-RPQMS compensation reactive and negative sequence is studied from the two aspects of voltage and current vector relation and power control,and the mathematical formula is deduced.Then,the thesis introduces the common current detection method and the principle of single-phase phase-locked loop.The good reactive current detection method and phase-locked loop technology are the basis of effectively treating the power quality problem of electrified railway.The back-to-back converter is deduced in two-(PR)control of the direct current control method,the method does not need to undergo multiple coordinate transformation,the control signal without decoupling,can achieve the AC signal without static adjustment,the DC voltage and the power outer loop using the PI controller,and derive the mathematical parameters of the controller parameters.At the same time,considering the DC voltage ripple causes the harmonic side of the converter to produce the harmonics,a resonant feedforward control method is proposed to compensate the double frequency component of the DC voltage and verified by simulation.Finally,the parameter design of the principle prototype system is carried out,the simulation model is set up on the Simulink platform of MATLAB software,and the effect of negative and reactive power problem of electrified railway power quality control system is analyzed,and the correctness and feasibility of the proposed control method are verified.