A shunt active power filter applied to high voltage distribution lines

The high requirement of rated power of an active power filter leads to high costs and limits the range of operation especially for high voltage applications. To overcome these problems, a combined system of a passive filter, using only one LC filter tuned to the lowest typical line current harmonic, and a shunt active power filter, sharing the filter capacitor to be decoupled from the fundamental line voltage, is proposed. These features strongly decrease the rated power of the active filter which is controlled only to suppress the harmonics of higher order and to eliminate resonance effects between the line impedance and the passive filter.