Characteristics of active power filter controlled by the use of extension pq theory

In this paper, the authors propose a calculation method for the compensating current reference of the 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 intelligent power module 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.