Defining Power Components in Nonsinusoidal Unbalanced Polyphase Systems: The Issues

Defining power components for unbalanced three-phase systems operating under nonsinusoidal conditions is an area of active research which spawned many theories. The approaches may be classified into two groups: the first is a bottom-up approach that extends well accepted definition of power components for single-phase systems operating under ideal sinusoidal situations to the case of unbalanced three-phase systems in nonsinusoidal situations. The second group involves a top-down approach that tries to offer a definition for nonlinear polyphase systems in nonsinusoidal situations and apply it to linear single phase systems in sinusoidal situations by considering the former as the general case and the latter as a special case. This paper summarizes previously published approaches and concludes that none of the approaches in the literature can lead to power components definitions that satisfy all required power properties. Different analysis tools other than those based on frequency or time domain are recommended in this paper for future work.