Research On Repeatitive Control Technology Of Active Power Filter Based On Predictive Model

Currently,active power filter(APF)as the most effective means in harmonic control,its key technology has become a research hotspot.In this paper,for the problem of delay in the APF control process,a harmonic compensation method based on combination of predictive function model and improved repetitive control is proposed,and the implementation process of this method in APF is studied.Firstly,for the problem of digital sampling delay in harmonic current detection,a reconstruction method for continuous and derivative random functions is proposed.According to the same conditions of the current value of the function,the first derivative value and the second derivative value,the reconstructed quadratic prediction function can accurately predict the next time value of the original function.The method of discretization of the reconstruction function is given,and the parameters of the prediction function model are optimized by using recursive least square method to further improve the prediction accuracy.Secondly,in order to realize the non-stationary tracking of the harmonic current signal and weaken the influence of the digital sampling delay,a control method using the combination of predictive function control and improved repetitive control is proposed.The detected load current is predicted using the predictive function model,and the harmonic current value is separated by the ip-iq harmonic current detection method.Then the detected harmonic current value is used as the command signal in the compensation circuit,and the PWM signal is generated by the tracking control of the command signal through the repeated control method.So that the inverter generates a compensation current to achieve harmonic current compensation.Finally,the simulink module in MATLAB simulation software is used to build the simulation model of the APF system to verify the accuracy and effectiveness of the predictive function model on APF.The simulation results show that the control method based on the combination of the predictive function model and the improved repetitive control not only has good prediction accuracy for harmonic currents,but also has a good compensation effect on the harmonic current in the power grid.