Sensor fault reconstruction for wind turbine benchmark model using a modified sliding mode observer

This paper proposes a fault diagnosis scheme applied to a wind turbine system. The technique used is based on a modified sliding mode observer (SMO), which permits the reconstruction of actuator and sensor faults. A wind turbine benchmark with a real sequence of wind speed is exploited to validate the proposed fault detection and diagnosis scheme. Rotor speed, generator speed, blade pitch angle, and generator torque have different orders of magnitude. As a result, the dedicated sensors are susceptible to faults of quite varying magnitudes, and estimating simultaneous sensor faults with accuracy using a classical SMO is difficult. To address this issue, some modifications are made to the classic SMO. In order to test the efficiency of the modified SMO, several sensor fault scenarios have been simulated, first in the case of separate faults and then in the case of simultaneous faults. The simulation results show that the sensor faults are isolated, detected, and reconstructed accurately in the case of separate faults. In the case of simultaneous faults, with the proposed modification of SMO, the faults are precisely isolated, detected, and reconstructed, even though they have quite different amplitudes; thus, the relative gap does not exceed 0.08% for the generator speed sensor fault

Low-cost real-time internet of things-based monitoring system for power grid transformers

One of the most common causes of blackouts is unexpected failures at power system transformer levels. The purpose of this project is to create a low-cost Internet of things (IoT)-based monitoring system for power grid transformers in order to investigate their working status in real-time. Our monitoring system’s key functions are the gathering and display of many metrics measured at the transformer level (temperature, humidity, oil level, voltage, vibration, and pressure). The data will be collected using various sensors connected to a microcontroller with an embedded Wi-Fi module (DOIT Esp32 DevKit v1), and then supplied to a cloud environment interface with a full display of all the ongoing changes. This technology will provide the power grid maintenance center with a clear image of the transformers’ health, allowing them to intervene at the right time to prevent system breakdown. The method described above would considerably improve the efficiency of a power transformer in a smart grid system by detecting abnormalities before they become critical

Étude des propriétés de transport électronique des métaux de transition et des alliages liquides

The electronic transport properties of liquid transition metals and liquid binary alloys have been studied in the framework of Ziman's formalism for pure metals and the Faber-Ziman formalism for alloys. For the liquid 3d transition metal series the resistivity and the thermoelectric power have been determined using a spin polarized approach. This approach assumes the existence of a liquid paramagnetic phase with transition metal atoms bearing a magnetic moment. The influence of our assumption of the transport properties is evidenced by comparison of the non-magnetic results with the magnetic ones. The values of the resistivity calculated in the spin polarized approach are lower than those obtained with the classical approach. However, both calculations overestimate the experience as do all the results of the litterature based on Ziman's formula. Nevertheless, the spin polarized apporach has the advantage to provide currently closest results to the experience. For the binary alloys the influence on the resistivity of the immediate environment of an atom in the liquid phase has been evaluated? For that purpose an alloy potential has been constructed in terms of radial distribution functions describing the local order. The alloy potential clearly improves the resistivity results with respect to those calculated within the phase shifts of pure metals. Another very interesting contribution concerns the origin of the alloy resistivity maximum wich is attributed without ambiguity to the presence of cesium d conduction states. The alloy potential emphasizes this effect. The study is completed by inserting the effect of the bulk of alloy in calculation of the resistivityNous avons étudié les propriétés de transport électronique des métaux de transition et des alliages binaires liquides dans le cadre du formalisme de Ziman pour les corps purs et de Faber-Ziman pour les alliages. Pour la série 3d des métaux de transition à l'état liquide, la résistivité et le pouvoir thermoélectrique ont été déterminés en utilisant une approche à spins polarisés. Cette approche suppose l'existence d'une phase liquide paramagnétique dans laquelle les métaux de transition portent un moment magnétique. Les valeurs des résistivités calculées dans l'approche à spins polarisés sont systématiquement inférieures à celles provenant du calcul non magnétique. Cependant les deux résultats surestiment l'expérience comme le font tous les résultats de la littérature basés sur l'emploi de la formule de Ziman. Néanmoins l'approche à spins polarisés a le mérite de fournir actuellement les résultats les plus proches de l'expérience. Pour les alliages binaires nous avons évalué l'influence de l'environnement immédiat d'un atome sur les valeurs de la résistivité. A cet effet nous avons construit un potentiel de l'alliage à partir des fonctions radiales décrivant l'ordre local. Le potentiel de l'alliage améliore les résistivités par rapport à celles calculés avec les déphasages des corps purs. Un autre aspect très intéressant concerne l'origine du maximum de la résistivité de l'alliage Na-Cs. Il est attribué sans ambiguïté à la présence d'états de conduction à caractère d provenant du césium. L'étude est complétée en insérant l'effet du volume de l'alliage dans le calcul de la résistivit

Étude des propriétés de transport électronique des métaux de transition et des alliages liquides

METZ-SCD (574632105) / SudocSudocFranceF