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Entropy and coefficient of variation (CV) as tools for assessing power quality
Entropía y coeficiente de variación (CV) como herramientas para evaluar la calidad de la energía
Keywords:
Power Quality, Harmonics, Entropy, Wavelets, nonlinear loads, Magnetic wave, Coefficient of variation (en)Calidad de la energía, armónicos, entropía, Wavelets, cargas no-lineales, onda magnética, coeficiente de variación (es)
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.
Este artículo presenta varios conceptos técnicos para cuantificar la entropía de la señal eléctrica y la variabilidad con el fin de evaluar la calidad de la energía, mostrando sus irregularidades, como la onda sinusoidal eléctrica, que suministra energía a la industria y a los hogares. El documento examinará estos conceptos y mostrará algunas medidas de ondas magnéticas radiadas por los circuitos de las líneas eléctricas de la ciudad de Manizales (Colombia) tomadas por debajo de 115 KV, por medio de una medición no invasiva e indirecta de la complejidad de la corriente transportada por el suministro. La entropía, como un indicador aceptado de la complejidad de la realidad física, es proporcional al logaritmo del número de estados en un sistema termodinámico. Algunos autores identifican la entropía como un desorden de un sistema, pero esto no es del todo cierto. La entropía de la información se definió por primera vez por Shannon en 1949, y se aplica a múltiples eventos físicos. En este contexto, la entropía describe la complejidad de la onda magnética radiada por la línea. Además, se obtuvo el coeficiente de variación (CV) espectral y de amplitud de las ondas magnéticas con un algoritmo Wavelet de multirresolución, que permite la medición de la dispersión en la distribución de datos. Es un número adimensional que facilita la comparación de la variación de los datos magnéticos radiados, con valores medios muy diferentes, frente a una onda magnética pura de 60 Hz como referencia.
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Copyright (c) 2011 J. H. Estrada, E. A. Cano-Plata, C. Younes-Velosa, C. L. Cortés
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