Discussion on Useless Active and Reactive Powers Contained in the IEEE Standard 1459

Abstract

This paper deals with the useless active powers and the reactive powers included in the unbalance power (SU1), and in the nonfundamental effective apparent power (SeN) defined in IEEE Standard 1459. Only the fundamental positive-sequence active power (P1+) must be delivered to loads under ideal supply operating conditions. Fundamental negative- and zero-sequence active powers (P1- and P10 , respectively), and the harmonic active power (PH) are considered useless active powers because they increase the power losses in the load and in the distribution lines, reducing the global efficiency of the electrical power systems. SU1 and SeN are calculated in this paper for two cases, resolving the effective apparent power (Se) by means of the product between the terms of the effective voltage (Ve) and the effective current (Ie). It yields to expressions of some useless active powers and reactive powers that differ from the definitions included in IEEE Standard 1459. New definitions of Ve, Ie, and Se are proposed to avoid the disagreements detailed in this paper. The new definitions are compared with the IEEE Standard 1459 definitions by means of one numerical example. Magnitudes calculated by means of the IEEE Standard 1459 definitions present a general overvaluation that arrives at a maximum of 83% for SU1.