Abstract
In this paper, the authors propose the calculation method of the active power filter compensating current, where a nonlinear load exists in the three-phase three-wire unsymmetrical voltage system. This new method has been named extension pq method. The authors have experimented with the extended pq methods and the usual pq method, using a 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.
