A new definition of instantaneous active-reactive current and power based on instantaneous space vectors on polar coordinates in three-phase circuits

This paper proposes a new definition of the instantaneous active-reactive current and power based directly on instantaneous space vectors on polar coordinates, and presents its application. The definition is applicable in three-phase three-wire systems. The instantaneous active-reactive power and current on α-β orthogonal coordinates have been defined by the so-called p-q theory. In comparison with the p-q theory, our new definition offers a lucid physical concept for the active-reactive current and power in three-phase circuits. The new method, thus, can decompose current into the instantaneous active and reactive currents without calculating the instantaneous active and reactive powers. An application example is presented to confirm the validity and practicability of the new definition using digital simulation