Passivity-based control for three-phase four-leg shunt active power filter

Shunt active power filters (APF) have been proved as useful elements to correct distorted currents caused by nonlinear loads in power distribution systems. Traditional control APF uses the PI controller with less stability. This paper presents a passivity-based control (PBC) strategy for three-phase four-wire shunt active filter to correct the output current waveform of three-phase four-wire shunt active power filter, PBC can guarantee APF system dynamic stability. Hamiltonian model of APF is built. A novel space vector modulation is applied to three-phase four-leg active filter. The new algorithm uses abc coordinates avoiding the ¿ß¿ transformation, which makes the selection of the switching vectors and duty cycles easier and drastically reducing the complexity of modulation algorithm. The controller design procedure is analyzed in detail. Theoretical analysis and experimental results demonstrate the validity of the proposed method, the filtering performance is improved obviously.