LCL Type Grid-connected Inverter Based On Active Disturbance Rejection Control Strategy Research

In the field of new energy development and utilization,distributed generation technology has been vigorously developed due to its advantages of high efficiency and environmental protection.As a bridge connecting this technology with the power grid,the core component of grid-connected inverter is filter,so the control performance of filter will directly affect the quality of grid-connected current.However,there are still some problems affecting its performance,such as inherent resonance and complex coupling.The linear active disturbance rejection control(LADRC)strategy adopted in this paper not only requires low model accuracy,but also can effectively solve the complex problems of inherent resonance and coupling.The specific work of this paper is as follows :Firstly,this paper starts from the LCL three-phase grid-connected inverter model,establishes its mathematical model in different coordinate systems,analyzes its model characteristics,and designs the parameter range of the LCL filter.Finally,the simulation model is built to verify the parameters.Secondly,according to the principle of LADRC control,a third-order LADRC controller is designed.The disturbance rejection and tracking performance of the controller are analyzed,and static and dynamic simulation experiments are carried out.Although the experimental results prove the feasibility of the controller,it also exposes the problems of the controller,such as : complex design;parameter setting is difficult.Finally,aiming at the shortcomings of the internal model control(IMC)strategy in the LCL grid-connected inverter,the idea of active disturbance rejection is introduced.In order to simplify the design of the controller,the linear state observer(LESO)is reduced from the third order to the first order,and then combined with the IMC controller.The observer can observe and compensate the disturbance in real time,and the IMC is easily affected by parameter changes,which leads to model mismatch.A control strategy based on LESO-IMC is designed.Through simulation experiments,it is proved that the control strategy designed in this paper has better immunity and stability.