Reference active source current for active power filter in an unbalanced three-phase system via the method of instantaneous power theory

A method that uses the principle of geometrical similarity to process the zero-axis voltage and current into zero-sequence active current was used to generate the reference active source current in active filter operating under unbalanced three-phase sinosoidal system. Using the theoretical formulations, it was observed that the proposed method obtained the same results as the equal resistance synchronous detection method. The reference active source current is sinusoidal and in-phase to source voltage, and can be calculated without O-d-q axis conversion. From computer simulations and circuit implementations, both results are satisfactory and have very good agreement.