Wye Apparent Power — An alternative proposal

This paper proposes another method of apparent power formulation in time-domain. It intents to be an alternative of the prevalent theories: American (IEEE Std 1459-2000) and European (FBD) methods. This method, called “Wye Apparent Power” is here presented in three different ways in the time-domain: i) using instantaneous values, ii) using collective rms values and iii) using polar coordinates. All of them have no restriction with regard to asymmetric, unbalanced and/or distorted signals. The application of these formulations requires an adequate quantity of samples, obeying the Nyquist Criterion, which can be used in numeric meters for power measurements. One of the advantages of using these formulations presented in this paper is their simplicity. The polar coordinate decomposition, for example, uses only basic mathematics operations. The use of the three approaches in a sinusoidal system shows clearly that the difference among them is related just with the existence of zero sequence components.

I. Introduction

As suggested by Buchholz [1], a three phase electrical circuit, with unbalanced voltages and currents, may be represented by an equivalent circuit, with balanced voltages and currents, which enable the same power flow. This idea had already been utilized for apparent power deduction by IEEE Std 1459–2000 [2].