A potência aparente em sistemas trifásicos a três-fios no Padrão IEEE 1459-2010

Abstract

This work discusses the apparent power definition, controversial in distorted and unbalanced three-phase systems. First, a review of the basic concepts necessary to the good understanding of the subject is carried out, i.e., of the electric quantities such as voltage, current, impedance and power in single-phase systems. Then, these same concepts are presented in the context of three-phase balanced, unbalanced, and distorted systems, serving the development of the apparent power concept in those situations, which is minutely discussed when an unequivocal definition is not possible. The text gives more attention to three-phase three-wire systems when it comes the moment of distinguishing both possibilities, not failing in bringing relevant comments on three-phase four-wire systems. The IEEE Standard 1459-2010, an international standard that brings definitions for the measurement of electric power quantities, is used as guidance to the work, but not being limited to it: a comparison between the system’s effective power in IEEE Standard 1459-2010 method and the system’s collective power by FBD-method is performed. Apparent power definitions based on the formulation as described by Buchholz in 1920 are highlighted and encouraged. Power factor, main object of discussion in the text after apparent power, is formulated to the analyzed situations. After the theoretical discussion, computer simulation results comparing the definitions presented in the IEEE Standard 1459-2010 for several load and voltage situations are shown, other than discussing the implications of such results. Finally, it is concluded that apparent power as defined by Buchholz is the basis for the currently most accepted resolutions in the context of unbalanced and distorted three-phase systems.