Comparison of instantaneous reactive power p–q theory with theory of the current's physical components

Abstract

The comparison of the instantaneous reactive power (IRP) p–q theory with the theory of the current's physical components (CPC) presented in this paper provides the relationship between powers in both theories applied to three-phase, three-wire circuits with sinusoidal voltages and currents. It shows that results of the instantaneous reactive power p–q theory are inconsistent with power phenomena in such circuits. Namely, the IRP q may occur in circuits with linear, purely resistive loads thus, with zero reactive power, Q, and the instantaneous active power p may occur in circuits with purely reactive loads, thus, with zero active power, P. Consequently, the IRP p–q theory fails to identify the power properties of three-phase circuits with unbalanced loads. Moreover, in spite of sinusoidal supply and the lack of distortion, the IRP p–q theory suggests that the active and reactive currents contain a third-order harmonic. Also the IRP p–q theory is not capable of providing information on power properties of the load instantaneously.