Field results on developed three-phase four-wire Shunt Active Power Filters

This paper presents three-phase four-wire shunt active power filters with ability to compensate current harmonics, power factor, and current unbalance. The power stage of the active power filters is based on a two-level four-leg inverter. The switching technique is based on an optimized periodic sampling strategy, and the digital controller uses the Theory of instantaneous reactive power (p-q Theory) expanded for three-phase four-wire systems. The presented active power filters were successfully demonstrated in four different facilities. The presented experimental results show the performance of the active power filters in operation with very different load profiles.