Research On Harmonic Control Of Electrified Railway Based On Cascaded Active Power Filter

With the continuously push forward the process of railway undertakings,China’s railway electrification rate has reached more than 70%.A series of power quality problems have become prominent with rapid development.Due to the nonlinear time-varying load in the electrified railway,which have a significant impact on the power quality of the electrified railway,and it has brought problems such as negative sequence,harmonics and reactive power.These problems affect the normal operation of electric locomotives and electrified railways,and also disrupt the normal operation order of railways.To solve the negative impact of harmonics on electrified railways and traction loads,this paper uses H-bridge cascaded active power filter(APF)of the straight traction network to compensate the harmonics of electrified railway systems.This paper introduces the composition and electrical characteristics of China’s electrified railways,introduces the working principles of SS9 electric locomotives and CRH380 A electric locomotives,building simulation models of two types of locomotives,clearing the goal of power quality management.The structure,working principle and carrier phase shift modulation technique of H-bridge cascaded active filter are analyzed,and the main circuit parameters of H-bridge cascaded APF are designed.In this paper,the adaptive variable step size algorithm based on class sigmoid function is improved.The improved algorithm’s time-varying tracking ability is enhanced and the detection accuracy is also improved.For the current tracking control strategy,the repetitive controller and the traditional PI controller are analyzed,the advantages of the two are combined,and a compound controller in which the repetitive controller and the PI controller are connected in series is proposed to ensure a high tracking accuracy while ensuring the response speed,the detailed design process is given in the article.DC voltage control uses fuzzy PI control to ensure that it can be stabilized quickly,and PI control is used to balance the DC side capacitor voltage.The MATLAB/SIMULINK software is used to simulate and verify the control method of H-bridge cascaded APF.To further investigate the effects of pulling traction load parameters and power supply system for electrified railway harmonic,using MATLAB / SIMULINK built traction power supply system V/X terminal,the AT mode power supply,analog,harmonic electrified railway system under different operating conditions content.Finally,the cascaded APF is installed into the traction power supply system,and its harmonic control effect is simulated and verified to prove the rationality and effectiveness of the design scheme proposed in this paper.