Over the past few years, power quality (PQ) monitoring has become of paramount importance for utilities and users since poor PQ generates negative consequences. In monitoring, fast detection and accurate classification of PQ disturbances (PQDs) are desirable features. In this work, a new method to detect and classify PQDs is proposed. The proposal takes advantage of the low computational resources of both a phasor measurement unit (PMU)-based signal processing scheme and the homogeneity approach. To classify the PQDs, if–then–else rules are used. To validate and test the proposal, synthetic and real signals of sags, swells, interruptions, notching, spikes, harmonics, and oscillatory transients are considered. For the generation of real signals, a PQD generator based on a power inverter is used. In the proposed method, the PMU information is directly used to classify sags, swells, and interruptions, whereas the homogeneity index is used to distinguish among the remaining PQDs. Results show that the proposal is an effective and suitable tool for PQ monitoring.

En este trabajo se propone una nueva ecuación diferencial fraccionaria que describe la ley de enfriamiento de Newton. El orden de la derivada a considerar es 0<g ≤1. Para mantener la consistencia con la ecuación física se introduce un nuevo parámetro σ. Este parámetro caracteriza la existencia de estructuras fraccionarias en el sistema. Se muestra que existe una relación entre el orden de la derivada fraccionaria g y el nuevo parámetro σ. Debido a esta relación las soluciones de las correspondientes ecuaciones diferenciales fraccionarias están dadas en términos de la función de Mittag-Leffler, cuyas soluciones dependen sólo del orden fraccionario g. Los casos clásicos son recuperados en el límite cuando g=1.

Phasor measurement units (PMUs) have become powerful monitoring tools for many applications in smart grids. In order to address the different issues related to harmonics in power systems, the fundamental phasor estimator in a PMU has been extended to the harmonic phasor estimator by several researchers around the world. Yet, the development of harmonic phasor estimators is a challenge because they have to consider time-varying frequencies since the frequency deviation in the harmonic components is proportional to the harmonic order in a dynamic way. In this work, a new algorithm for harmonic phasor estimation using an instantaneous single-sideband (SSB) modulation is presented. Unlike other SSB-based approaches, its implementation in this work is based on concepts of instantaneous phase and instantaneous frequency. In general, the proposed algorithm is divided into two stages. Firstly, the estimation of the fundamental phasor is carried out by means of a complex finite impulse response (FIR) filter which provides the analytic signal used to compute the instantaneous magnitude, phase, and frequency. Secondly, a complex FIR filter bank is proposed for the estimation of the harmonic components, where the instantaneous SSB modulation technique is applied in order to center the harmonic components into specific narrow bands for each complex filter when an off-nominal frequency occurs. The validation of the proposed algorithm is carried out by means of the current standards of phasor measurement units, i.e., Std. C37.118.1-2011 and C37.118.1a-2014, which involve steady-state, dynamic, and time performance tests.

Phasor measurement units (PMUs) are important elements in power systems to monitor and know the real network condition. In order to regulate the performance of PMUs, the IEEE Std. C37.118.1 stablishes two classes—P and M, where the phasor estimation is carried out using a quadrature oscillator and a low-pass (LP) filter for modulation and demodulation, respectively. The LP filter plays the most important role since it determines the accuracy, response time and rejection capability of both harmonics and aliased signals. In this regard and by considering that the M-class filters are used for more accurate measurements, the IEEE Std. presents different M-class filters for different reporting rates (when a result is given). However, they can degrade their performance under frequency deviations if the LP frequency response is not properly considered. In this work, a unified model for magnitude compensation under frequency deviations for all the M-class filters is proposed, providing the necessary values of compensation to improve their performance. The model considers the magnitude response of the M-class filters for different reporting rates, a normalized frequency range based on frequency dilation and a fitted two-variable function. The effectiveness of the proposal is verified using both static and dynamic conditions for frequency deviations. Besides that, a real-time simulator to generate test signals is also used to validate the proposed methodology.

Time synchronization (TS) represents an important necessity for many industries in fields such as communications, manufacturing, and power systems related to electrical networks, microgrids, and renewable energies, among others, because it can ensure that cooperating processes or systems can interoperate correctly; further, the scheduling of specific tasks through a timestamp can be done. Among different synchronization protocols, the inter-range instrumentation group (IRIG)-B time code has become one of the most employed in real-time information transmission systems because of its accuracy, robustness, and simplicity. In this paper, a field programmable gate array (FPGA)-based IRIG-B decoder is presented. The FPGA used is a Cyclone IV EP4CE115F29; yet, the proposed hardware implementation has a vendor independency. On the other hand, the IRIG-B output is provided by a SEL-2401 Satellite-Synchronized Clock. Results show that the proposal can provide a reliable and accurate time source using the IRIG-B time code. Regarding the FPGA, a low resource usage of the chip is obtained; besides, thanks to its high capabilities of integration and parallelism, a widely number of applications can be incorporated.