Characteristics of three phase active power filter using extension pq theory

In this paper, the authors propose a calculation method for the compensating current reference of an active power filter, where a nonlinear load exists in a three-phase three-wire unsymmetrical voltage system. This new method has been named the extension pq method. The authors have experimented with the extension pq method and the pq method, using the same current controlled IPM inverter for both methods. The results of the experiments proved that, in the unsymmetrical voltage system, the source current was distorted in case of the pq method, but undistorted in case of the extension pq method.