This paper presents a comparative analysis of three current decomposition methods in three-phase systems on the basis of some case studies. The analysis takes into consideration the Currents’ Physical Components (CPC), the p-q theory of the instantaneous power and a modified variant of the Akagi’s components proposed by the authors. The proposed manner of interpretation based on p-q theory of instantaneous power removes Czarnecki’s critical remarks related to Akagi’s definitions and makes similar the two theories at least under sinusoidal voltage conditions. It can be concluded that the original p-q theory is false under unbalanced loading conditions and that the proposed reconsideration of the current’s active and reactive components is needed in order to avoid coming into conflict with physical phenomena.

Keywords: Complex apparent power, p-q theory, Currents’ Physical Components, Active current, Reactive current, Unbalanced systems