Research On Control Strategy Of Active Power Filter Based On Linear Extended Observer

With the increasing demand for power supply and the diversification of power supply equipment,a large number of nonlinear loads enter the power grid,which makes the problem of power quality increasingly prominent.The existence of this problem has brought a great threat to the safe and stable operation of power supply system,among which harmonics is an important factor affecting power quality.In order to better deal with the power quality problems caused by harmonics,harmonic filtering equipment is also developing constantly.Active Power Filter(APF)is widely used in Power system because of its unique advantages.This paper takes APF as the control object,and its main work includes:(1)Based on APF,the research background and significance of this topic are briefly introduced,the working principle of APF is described,the topological structure diagram of active power filter is built,and the mathematical model is built according to the topological structure;And confirmed the APF capacity,DC bus voltage,dc side capacitance parameters.(2)The design of Linear Active Disturbance Rejection Controller(LADRC)makes parameter adjustment more convenient,but the control performance is reduced to some extent compared with NLADRC.To solve this problem,this paper presents an improved active disturbance rejection control strategy for APF current tracking control.An improved Linear Extended State Observer(LESO)is established by exploring the principle of deviation adjustment to ensure that the total disturbance can be estimated in a relatively timely and accurate manner.At the same time,the backstepping design method is used to design the control law with Lyapunov function,and the backstepping method is combined with the improved LESO to ensure the stability of the system and further improve the anti-interference ability.The stability analysis was also carried out.Finally,the control effect of APF improved active disturbance rejection controller is simulated.(3)According to APF model,the traditional LADRC model with output current as the controlled object is established,and the control performance of traditional LADRC is analyzed.In order to reduce the dependence of the controller on LESO and deal with the interference more effectively in the control process,a robust integral control method based on LESO is designed in this paper.The controller is composed of robust Error sign integral Controller(RISE)and LESO.LESO can effectively overcome the disadvantage of RISE’s reliance on perturbation prior knowledge and reduce its design conservatism.RISE can effectively reduce the estimated load of the observer,reduce its bandwidth requirements,while maintaining fast response speed and good anti-interference performance.Finally,the asymptotic stability of the control strategy is proved,and its superior control ability is verified by simulation results.