AC Power Theory From Poynting Theorem: Accurate Identification of Instantaneous Power Components in Nonlinear-Switched Circuits

Abstract

This paper contributes to narrowing the long-standing theoretical gap with power theory (or “power definitions”) for nonlinear ac switching circuits. The true instantaneous energy transformation and storage components of ac circuits are identified from the Poynting Theorem. This paper tackles the problem of power identification from the most general form of energy conservation. Therefore, it is no longer necessary to mathematically “define” powers to fit the engineering solution of a problem. The identification technique does not present problems with physical meaning since it is in full agreement with Maxwell's Equations. In this paper, the method is applied to the identification of the power components of single-phase switched circuits. Instantaneous energy is decomposed only into energy transformed (related to active power) and energy stored (related to reactive power). Examples that have caused physical interpretation problems with other power theories are presented for illustration and validation.