Reduced-order Active Disturbance Rejection Control of DC-Link Voltage of Photovoltaic Grid-connected Inverters

The robust stability of the dc-link voltage is extremely important for energy conversion in photovoltaic (PV) grid-connected systems, but its control performance is constrained by uncertain factors such as temperature, irradiance and the grid. To cope with this issue, an active disturbance rejection control (ADRC) controller is presented in this paper to achieve strong tolerance to various disturbances. Based on the power balance model on the dc link, a reduced-order observer is constructed, which aims to improve the estimation ability of the total disturbance. The observer avoids the repeated estimation of the known state, and fulfills a relatively superior dynamic response. Finally, theoretical analysis and simulation results are carried out to verify the feasibility and effectiveness of the proposed ADRC strategy.