Abstract

ESTRADA, J. H.; CANO-PLATA, E. A.; YOUNES-VELOSA, C.  and  CORTES, C. L.. Entropy and coefficient of variation (CV) as tools for assessing power quality. Ing. Investig. [online]. 2011, vol.31, suppl.2, pp.45-50. ISSN 0120-5609.

This paper presents several concepts and techniques for quantifying electric signal entropy and variability for assessing power quality, showing their irregularities, such as the electrical sine wave which delivers power to industry and homes. The paper will review these concepts and show some magnetic radiated waves measurements taken below 115 KV electricity line circuits in the city of Manizales (Colombia) through non-invasive and indirect measurement of the complexity of the current transported by the supply. Entropy, as an accepted indicator of physical complexity, is proportional to the logarithm of the number of states in a thermodynamic system. Some writers have identified entropy as being system disorder, but this is not completely true. Entropy of information was first defined by Shannon in 1949 and it is applied to many physical events. Entropy has been used for describing the complexity of the magnetic wave radiated by the line in this paper. Furthermore, the magnetic waves' spectral and amplitude coefficient of variation (CV) were obtained using a multi-resolution wavelet algorithm which measures data distribution dispersion. It is a dimensionless number allowing the variation of magnetic radiated data having significantly different mean values to be compared to a 60 Hz pure magnetic wave as reference.

Keywords : Power Quality; Harmonics, Entropy; Wavelets, nonlinear loads; Magnetic wave; Coefficient of variation.

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