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Concept

Intermodulation

L'intermodulation sert à désigner, en électronique analogique, un défaut de certains amplificateurs qui peut être particulièrement gênant pour les amplificateurs hautes fréquences destinés aux radiocommunications. Les phénomènes d'intermodulation concernent également des défauts de transducteurs, notamment électro-acoustiques, et des phénomènes vibro-acoustiques. Description Un amplificateur linéaire parfait restitue sur sa sortie un signal de plus grande amplitude, mais de même forme que le signal d'entrée. Si le signal de sortie n'a pas la forme du signal d'entrée, on dit qu'il y a distorsion. Il y a distorsion si:

le spectre du signal d'entrée n'entre pas dans la bande passante de l'amplificateur ;

la phase ne varie pas linéairement en fonction de la fréquence (distorsion de temps de propagation de groupe) ;

il y a une non linéarité d'amplitude.

Cette dernière distorsion est dite distorsion harmonique. Une sinusoïde en entrée donnera une autre forme d'onde en sor

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PMU-Based ROCOF Measurements: Uncertainty Limits and Metrological Significance in Power System Applications

Asja Derviskadic, Guglielmo Frigo, Mario Paolone, Yihui Zuo

In modern power systems, the Rate-of-Change-of-Frequency (ROCOF) may be largely employed in Wide Area Monitoring, Protection and Control (WAMPAC) applications. However, a standard approach towards ROCOF measurements is still missing. In this paper, we investigate the feasibility of Phasor Measurement Units (PMUs) deployment in ROCOF-based applications, with a specific focus on Under-Frequency Load-Shedding (UFLS). For this analysis, we select three state-of-the-art window-based synchrophasor estimation algorithms and compare different signal models, ROCOF estimation techniques and window lengths in datasets inspired by real-world acquisitions. In this sense, we are able to carry out a sensitivity analysis of the behavior of a PMU-based UFLS control scheme. Based on the proposed results, PMUs prove to be accurate ROCOF meters, as long as the harmonic and inter-harmonic distortion within the measurement pass-bandwidth is scarce. In the presence of transient events, the synchrophasor model looses its appropriateness as the signal energy spreads over the entire spectrum and cannot be approximated as a sequence of narrow-band components. Finally, we validate the actual feasibility of PMU-based UFLS in a real-time simulated scenario where we compare two different ROCOF estimation techniques with a frequency-based control scheme and we show their impact on the successful grid restoration.

2019

Chargement

Synchrophasor-Based ROCOF Measurements: Feasibility in Real-World Scenarios

Asja Derviskadic, Guglielmo Frigo, Mario Paolone

In modern power systems, Rate of Change of Frequency (ROCOF) is employed in monitoring and control applications. However, a standard approach towards ROCOF measurements is still missing. In this paper, we investigate the feasibility of Phasor Measurement Units (PMUs) deployment in ROCOF -based applications. For this analysis, we select three representative synchrophasor estimation algorithms and compare their accuracy in datasets inspired by real-world acquisitions. Based on the proposed results, PMUs prove to be accurate ROCOF meters, as long as the harmonic and inter-harmonic distortion within the measurement pass-band is reduced. In the presence of transient events, the synchrophasor model looses its appropriateness, as the signal energy spreads over the entire spectrum and cannot be approximated as a sequence of narrowband components. For these reasons, a re-definition of the IEEE Std. C37.118.1 requirements is recommended to suitably define ROCOF measurements based on real-world operating conditions.

IEEE2018

Chargement

Design and experimental validation of an FPGA-based PMU simultaneously compliant with P and M performance classes

Asja Derviskadic, Mario Paolone

Low-inertia grids are characterized by high shares of harmonic and inter-harmonic distortion, produced by the inverters that interface non-conventional generation assets to the electrical grid. These interfering tones largely compromise synchrophasor estimation and may jeopardize protection and control strategies based on Phasor Measurement Units (PMU). Indeed, the IEEE Std. C37.118 does not require resiliency against inter-harmonic tones for protection PMUs. In view of increasing synchrophasor technology reliability, the paper presents the design and the experimental validation of a PMU that is simultaneously compliant with both protection (P) and measurement (M) class of PMU performance defined in the IEEE Std. C37.118. The synchrophasor estimator is based on the interpolated DFT and iteratively estimates and compensates the effects of the spectral interference produced by a generic interfering tone and the negative image of the fundamental tone. The proposed hardware architecture is based on a Field Programmable Gate Array (FPGA).

2020

Chargement

Amplificateur électronique

thumb|Un amplificateur audio à tubes. Un amplificateur électronique (ou amplificateur, ou ampli) est un système électronique augmentant la puissance d’un signal électrique. L’énergie nécessaire à l’

Haut-parleur

vignette|Un haut-parleur électrodynamique. vignette|Schéma de coupe d'un haut-parleur électrodynamique. Un haut-parleur, ou hautparleur, est un transducteur électroacoustique destiné à produire des s

Radiodiffusion

La radiodiffusion est l'émission de signaux par l'intermédiaire d'ondes électromagnétiques destinées à être reçues directement par le public en général et s'applique à la fois à la réception indivi

MICRO-461: Low-power radio design for IoT

The basic function of an IoT node is to collect data and send it through a wireless channel to the cloud. Since the power consumption of an IoT node is largely dominated by the wireless communication, it is therefore key to understand the trade-offs faced when designing the radio.

EE-425: HF and VHF circuits and techniques I

Master the design of circuits and systems at high frequency (HF) and very high frequency (VHF) (1 MHz-6GHz). This lecture is particularly oriented towards circuit aspects of modern communications systems.

EE-520: Low-power analog IC design

This course presents the design of low-power analog CMOS integrated circuits. The techniques are based on the concept of inversion coefficient that can be used as the main design parameter for the optimization of figures-of-merit applied to circuits including amplifiers, filters and oscillators.