Disturbance Observer Based Control of Shunt Active Power Filter

In recent decades, governments and manufacturers have been focusing on "energy quality standards". The main objective is to prevent degradation of voltage-current levels due to harmonics and lowpower factor. Active Power Filters (APF) are energy quality devices to mitigate the before mentioned issues. This paper presents disturbance observer-based current control of three-phase APF. A three-phase power diode rectifier with resistive load was taken as the balanced nonlinear load. The modelling is based on the ABC-DQ transformation of the AC-system variables. The reference currents to be used by the current controllers extracted according to DQ-Theory. In the study, measured and calculated terms are substituted by using a disturbance observer, DOB. Thus, a parameter independent control structure is obtained. The voltage level of the DC-side is regulated by using a PI controller. Simulation results for the constant, variable, reactive load tests and variable grid frequency test confirm the performances considered theoretically for the APF topology.