A control method of active power filter in unsymmetrical voltage system

In this paper, the authors propose a calculation method for compensating the current reference of an active power filter, where a nonlinear load exists in a three-phase three-wire asymmetrical 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 an asymmetrical voltage system, the source current was distorted in the case of the pq method, but was not distorted in the case of the extension pq method.