A universal reference current generating method for active power filter

A reference current generating method for active power filter is proposed in this paper, which is applicable to the system with asymmetrical and/or harmonic current. By designing a filter in the d-q coordinate, the source´s positive sequence voltage is extracted from the asymmetrical and distorted source voltage, and is used to form the expected instruction current. Unlike the general approaches, such as the p-q theory and the i_p-i_q method, the proposed method can be applied without any limitation to the source, load and compensation purpose. Software simulation has verified the validity and feasibility of the proposed method.