A Virtual Instrument for the Measurement of IEEE Std. 1459-2000 Power Quantities

In this paper, the authors present a PC-based instrument for the measurement of electrical-power quantities defined in IEEE Std. 1459. The instrument is based on a time-domain technique for the detection of the fundamental and harmonic components of voltages and currents. The time-domain strategy was originally developed by the authors for three-phase, three-wire systems. In that paper, the strategy had been extended to both three-phase, four-wire and single-phase systems. Simulation tests were carried out to assess the uncertainty contribution of the proposed strategy in the absence of the measurement transducers. Moreover, the accuracy of the PC-based instrument with its transducers was evaluated; the experimental tests were carried out by using a power calibrator.

I. Introduction

In the past few years, harmonic distortion in power systems has drastically increased, because of the proliferation of nonlinear loads that draw nonsinusoidal currents. Thus, it has become a very important target of the definition of relevant electrical-power quantities, which can be used to evaluate power-quality levels at the metering section and to determine customer and utility pollution contributions, with respect to the harmonic distortion. At present, the international standards on the measurements of power quality and harmonic distortion in power systems [1], [2] define some methods to evaluate the harmonic-distortion levels; they refer to the measurement of traditional quantities, like amplitudes of singular harmonics and total harmonic-distortion (THD) factors. However, these quantities cannot usefully be employed for energy billing and responsibility attribution for the harmonic distortion. On the other hand, the definition and measurement of electrical-power quantities in nonsinusoidal situations have widely been discussed in the literature; several power theories have been formulated in order to extend the well-known concepts in sinusoidal conditions to systems with distorted voltages and currents. However, there is not yet generalized power theory that can be assumed as a common base for power-quality evaluation, harmonic-source detection, and compensation in power systems.