Research On Active Power Filter Control Strategy Based On Predictive Model

In recent years,with the increasing voice of encouraging the use of clean energy,the trend of electric energy gradually replacing the traditional fossil energy has been formed.This trend not only protects the environment and natural resources,but also puts forward new requirements for the grid ecology.The use of a large number of electrical equipment means that more kinds of power harmonics will enter the grid.Active power filter(APF)has good dynamic harmonic compensation characteristics and has been the main research object of scholars in related fields.This article takes the three-phase three-wire system LCL APF as the research object,and mainly studies the harmonic current detection and compensation based on the prediction function model.Firstly,a new harmonic current detection method is proposed to solve the problem of low harmonic current detection accuracy in traditional APF due to the delay caused by digital signal processing and the limitation of low-pass filter frequency band.In this paper,Kalman filter is used to replace the traditional low-pass filter.At the same time,a second-order autoregressive prediction function model is established at the front end of the harmonic current detection link to predict the load current,and the parameters of the model are rolling optimized using recursive least squares.The system directly performs harmonic current detection on the high-precision load current prediction value.Secondly,in order to cooperate with this improved harmonic current detection method to improve the compensation effect of the APF,the command current tracking control link uses a compound repetitive control strategy that combines PI control and repetitive control to perform no static error on the command current signal Tracking control to improve command current tracking control capability.In order to suppress the high-frequency ripple without increasing the active power loss of the system,an LCL filter based on the active damping method is used to reduce the ripple current entering the power grid.Finally,Matlab/Simulink simulation software was used to build a three-phase three-wire LCL APF system simulation experimental model to verify the feasibility of the improved harmonic current detection technology and the compensation strategy of the APF system.Simulation experiments prove that the proposed improved harmonic current detection technology has higher detection accuracy for harmonic currents,the command current of the APF compensation system has better static difference characteristics,and at the same time effectively reduces the ripples entering the power grid and makes the APF compensation effect significantly improved.