A dq0 passivity-based approach for 3φ four-wire shunt active power filter based on NPC three-level converter

This paper presents a dq0 control scheme for a three-phase four wire shunt active power filter (SAF) based on a three-level neutral point clamped (NPC) inverter. Neutral-point clamped inverter is a widely used topology for utility applications. However, the differential neutral point voltage is fluctuates with different switching states. This phenomenon has to be minimized or disappeared for all power applications. In order to improve the time response and behavior of SAF, a passivity-based controller (PBC) is proposed and designed in this work. The purpose of this kind of controller is to increase the operation region of the shunt active power filter regarding to the region gotten when a linear controller is designed around and operation point. The current control is performed by PBC and the voltage regulation of dc-link and the differential neutral point voltage are carried out by PIs. The proposed control scheme is verified by simulation tests under different loads condition.