Improved Active Disturbance Rejection Control for Single-Phase Grid-connected Inverter using Kalman Filter

Due to the non-ideal environment in distribution networks with background voltage harmonics and various operation characteristics in the inverter system as control parameter variations, modulation dead zones, etc., the power quality of the grid-connected inverter in distribution networks can be severely affected by the above issues which results to total harmonic distortion (THD) and control oscillation issues. In order to provide power quality improvement and gird oscillation suppression, an improved active disturbance rejection control (ADRC) method is proposed in this paper. The proposed method first performs accurate estimation of the state variables using the Kalman filter and then provides robustness control of the inverter current with an improved differential feedforward ADRC algorithm. Theoretical analysis between the proposed method and conventional ADRC algorithm is also provided illustrating the benefit of the proposed method. The effectiveness of the proposed method is verified through mathematical analysis and the simulation results on a MATLAB/Simulink-based inverter platform. And the results have shown strong oscillation suppression and disturbance rejection capabilities with improved current THDs.