ANALYSIS OF POWER PHENOMENON AND CLASSIFICATION OF REACTIVE POWER IN THREE-PHASE CIRCUIT

Detailed physical analysis of power phenomenon in three-phase circuit is given. It verifies that the total three phase instantaneous power cannot remain constant in circuits with distort and unbalanced source. This conclusion gives a further physical explanation of the active current defined by the universal instantaneous power theory (UIPT). This paper also points out: in nonsinusoidal and unbalanced circuit, there are not only reactive power flowing among phases, but also reactive power flowing between 3-phase source and 3-phase load. Proceeding from minimum transmission loss criterion, this paper presents the definition of reactive power flowing among phases and reactive power flowing between 3-phase source and 3-phase load. Active current, reactive current flowing among different phases and reactive current flowing between source and load have a pairwise orthogonal relationship in the framework of UIPT. If the reactive power flowing between source and load is ignored, the UIPT is identical with H.Akagi抯 reactive power theory.