Research On Control Strategy Based On Parallel Active Power Filter

The large-scale use of non-linear loads in power systems will lead to a gradual increase in harmonic current content,which will seriously affect the power quality of the power supply network.Therefore,appropriate harmonic current management methods should be adopted to improve the adverse effects of harmonic currents on the power grid.Due to the fast change of harmonic current and the complicated current content of each frequency,the traditional passive filter is difficult to meet the current demand for harmonic current control due to the limitation of its working principle.Compared with the traditional passive filter,the active power filter has the characteristics of good dynamic characteristics and high compensation accuracy,and the compensation effect is not easily affected by the grid voltage.Therefore,it has developed rapidly in practical applications and has become one of the most widely used methods in harmonic control.This paper discusses and studies the control strategy of the parallel active power filter.Firstly,the background meaning of active power filtering is analyzed,and its classification and working principle are briefly introduced.Subsequently,the paper studies the widely used adaptive harmonic detection method.This part first introduces the commonly used three harmonic current detection methods,and then focuses on the adaptive filtering algorithm,including the steepest descent algorithm and the minimum.Mean square algorithm and recursive least squares method.By studying and comparing the convergence speed,steady state error and computational complexity of these three algorithms,a variable step size minimum mean square algorithm is chosen to study,and finally a harmonic detection method based on affine projection is proposed.And the simulation experiment was carried out.In this paper,the hysteresis control method of timing comparison is used to track and control the command current,and the simulation modeling research is carried out.The main circuit is also analyzed and studied.Finally,the simulation and experimental verification are carried out in this paper.It can be seen from the simulation results that the algorithm and control strategy of this paper have important practical significance for harmonic control.Finally,the experimental platform of APF was built in the laboratory,and relevant experiments were carried out to verify the feasibility of the proposed control method.