Power factor correction and harmonic compensation in an active filter application through a discrete-time active disturbance rejection control approach

The problem of Active Disturbance Rejection control for active power filters subject to periodic disturbances is tackled by means of a discrete-time Generalized Proportional Integral (GPI) observer-based control. An extended state observer-based control scheme is proposed for the active filter application according to the Active Disturbance Rejection strategy. In this scheme, model uncertainties and external disturbances are included in a general additive disturbance input which is estimated on-line and subsequently rejected via the controller action. The observer carries out the disturbance estimation, thus reducing the complexity of the controller design. The controller efficiency is tested via realistic computer simulations of a one-phase shunt active power filter, performing a trajectory tracking task under nonlinear and linear loads for power factor correction and harmonic compensation purposes. Performance analysis for varying frequency conditions are also presented.