Abstract
Aiming at the problem of noise easily polluting the voltage measurement link of an inverter DC bus in photovoltaic grid, an improved linear active disturbance rejection control technology based on filter function is constructed by combining linear active disturbance rejection control technology with filter. The core of the method is to expand the filtered voltage into a new state variable and use the linear extended state observer to estimate the filtered voltage, which is used as the feedback quantity, to improve the ability of linear active disturbance rejection control technology to suppress high-frequency noise. Then, considering that the output of the system contains noise, the frequency domain characteristics of the improved linear active disturbance rejection control are analyzed theoretically and verified by Bode diagram simulation. Finally, the feasibility and effectiveness of the proposed control strategy are demonstrated by building a simulation platform for grid-connected PV inverter.
Highlights
An extensive amount of fossil fuel has caused severe damage to the environment, resulting in the deterioration of ecology
linear active disturbance rejection control (LADRC) has strong disturbance rejection and tracking performance, the large gain coefficient of linear extended state observer (LESO) will cause noise amplification problems, which will affect the stability of the controller [15]
To verify the effectiveness of the LADRC-RL controller with correction link analyzed in this study, a three-phase photovoltaic grid-connected system model was built based on MATLAB simulation software
Summary
An extensive amount of fossil fuel has caused severe damage to the environment, resulting in the deterioration of ecology. In the original ADRC, ESO and error feedback control rate are presented as nonlinear functions, and there are many tuning parameters, which is not convenient for practical applications To solve this problem, Professor Gao Z.Q. proposed linear active disturbance rejection control (LADRC) based on linear processing of the above two links, and determined the controller parameters by using bandwidth, which made the whole system easy to debug and practical applications [14]. LADRC has strong disturbance rejection and tracking performance, the large gain coefficient of LESO will cause noise amplification problems, which will affect the stability of the controller [15]. In [18], a predictive tracking differential active disturbance rejection controller is proposed, which can suppress the influence of noise and reduce the phase delay; it has the problems of poor dynamic performance and difficult parameter tuning. If Sa is the pulse of 0/1 corresponding to the open/close of the coupling lower bridge arms, for which Sa can be modeled as function (2):
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