A repetitive based controller for a shunt active filter to compensate for reactive power and harmonic distortion

This paper presents a repetitive-based controller for a single phase active filter to compensate for reactive power and current harmonic distortion, i.e., to guarantee a power factor close to unity. The topology selected for the active filter consists of a single phase full-bridge Voltage Source Inverter (VSI). The controller is based on a frequency domain description of the periodic disturbances. Adaptation is then introduced to cope with uncertainties in the disturbance signals and system parameters. A first observation is that the adaptations are reduced to a bank of resonant filters by means of suitable rotations, which are tuned at the frequencies of the harmonics under compensation. The second observation is that there exists an equivalent expression for such a bank of resonators in terms of a single delay line. Moreover, we show that this new expression for the controller, which belongs to the family of repetitive schemes, has a relatively simple implementation. The proposed control scheme has been experimentally tested in a 1.5 KVA prototype and the results are presented here.