Application Simulation Research Of Active Power Filter Based On Improved Active Disturbance Rejection Control

With the large-scale integration of new energy and the continuous increase of user electricity demand,a large number of nonlinear devices have been connected to the power grid,inevitably injecting harmonic components into the grid,which reduces the power quality and operational efficiency of the system.As an effective harmonic treatment tool,the Active Power Filter has been widely applied in power systems.However,the DC-side voltage of the active power filter fluctuates during operation,which affects the harmonic compensation effect.Therefore,many scholars have conducted in-depth research on the control problem of DC-side voltage to maintain its stability.The traditional proportional-integral control method is greatly influenced by the system model and has poor disturbance resistance,which cannot balance overshoot and speed.Active Disturbance Rejection Control enhances disturbance resistance by introducing disturbance compensation,it still has the problems of poor control accuracy and low harmonic compensation effect.Therefore,this paper introduces the adaptive linear prediction into the Active Disturbance Rejection Control to reduce the influence of system disturbances on the control process,improve the control accuracy of the voltage,and enhance the harmonic compensation effect.The important research contents of this paper are as follows:Firstly,the harmonic detection and tracking part of the Active Power Filter is studied.This paper compares the advantages and disadvantages of several existing harmonic detection and control methods,and selects the instantaneous reactive power theory-based harmonic detection method and the hysteresis comparison method to detect and control harmonic currents,respectively.Then,the model is established to verify the effectiveness of the method.Secondly,the control problem of DC-side voltage is studied.Firstly,the energy exchange between the DC-side and AC-side of the Active Power Filter and the fluctuation process of DC-side voltage are analyzed.A mathematical model for controlling the DC-side voltage is established based on this analysis,and the characteristics of traditional control methods and Active Disturbance Rejection Control are analyzed and compared based on this model.In order to further improve the tracking ability of the self-disturbance control method by reducing the influence of system disturbances on the control process,this paper introduces the adaptive linear prediction into the Active Disturbance Rejection Control and proposes an improved Active Disturbance Rejection Control method.At the same time,in order to solve the voltage drop problem caused by the introduction of the adaptive linear prediction,several adaptive algorithms are applied to the adaptive linear prediction,which further reduces the distortion rate of grid-side harmonics while ensuring the voltage control effect.On this basis,the overall model of the Active Power Filter is established and simulated.After comparing the simulation results under different voltage control methods,it is found that the distortion rate of grid-side harmonics is reduced by 0.9% compared to the traditional proportional-integral method,which verifies the superiority of the improved self-disturbance control method.Finally,this paper uses the Active Power Filter under the method of Active Disturbance Rejection Control to treat harmonic components in a photovoltaic grid-connected system to further verify the applicability of the method in photovoltaic systems.Firstly,the characteristics of the active power filter and the photovoltaic grid-connected system are analyzed,and the common control theory of the two systems is obtained.Based on this theory,the overall control model of the photovoltaic grid-connected system with active filtering function is established,and the model is built and simulated.The simulation results show that under the improved Active Disturbance Rejection Control method proposed in this paper,the system can stably operate under various grid conditions,and the harmonic compensation effect is significantly improved,which validates the applicability of the proposed method in photovoltaic systems.