Liste des documents
L’impact d’une Charge Fortement Capacitive Sur la Qualitédu Filtrage d’un FAP Contrôlé Par un Filtre Multi-VariableHautement Sélectif
This article is devoted to the depollution of the electrical supply networks by shunt active power filter (SAPF). We start by studying a self tuning filter (STF) based on Concordia transformation. This transformation is based on the extraction of the references of harmonic currents in the Concordia axis to compensate network harmonic and by consequence, improve the quality of power system. Next, we present the influence of a strongly capacitive load on the quality of the filtering of a SAPF controlled by a STF approach. This influence is validated by numerical simulations under Matlab-Simulink environment of a system of power PD3 a diode debited in a strongly capacitive load this results prove the major influence of this types of load in filtering quality. Voir les détails
Mots clés : SAPF, harmonic, STF, System of Power PD3, Quality of Energy, Strongly Capacitive Load, Concordia transformation
MULTI-OBJECTIVE PREDICTIVE CONTROL: A SOLUTION USING METAHEURISTICS
The application of multi objective model predictive control approaches is significantly limited with computation time associated with optimization algorithms. Metaheuristics are general purpose heuristics that have been successfully used in solving difficult optimization problems in a reasonable computation time. In this work , we use and compare two multi objective metaheuristics, Multi-Objective Particle swarm Optimization, MOPSO, and Multi-Objective Gravitational Search Algorithm, MOGSA, to generate a set of approximately Pareto-optimal solutions in a single run. Two examples are studied, a nonlinear system consisting of two mobile robots tracking trajectories and avoiding obstacles and a linear multi variable system. The computation times and the quality of the solution in terms of the smoothness of the control signals and precision of tracking show that MOPSO can be an alternative for real time applications. Voir les détails
Mots clés : Model predictive control, Metaheuristcis, Multiobjective Optimization
Modeling, control and fault diagnosis of an isolated wind energy conversion system with a self-excited induction generator subject to electrical faults
In this paper, a contribution to modeling and fault diagnosis of rotor and stator faults of a Self-ExcitedInduction Generator (SEIG) in an Isolated Wind Energy Conversion System (IWECS) is proposed. In orderto control the speed of the wind turbine, while basing on the linear model of wind turbine system about aspecified operating point, a new Fractional-Order Controller (FOC) with a simple and practical designmethod is proposed. The FOC ensures the stability of the nonlinear system in both healthy and faulty conditions.Furthermore, in order to detect the stator and rotor faults in the squirrel-cage self-excited inductiongenerator, an on-line fault diagnostic technique based on the spectral analysis of stator currents ofthe squirrel-cage SEIG by a Fast Fourier Transform (FFT) algorithm is used. Additionally, a generalizedmodel of the squirrel-cage SEIG is developed to simulate both the rotor and stator faults taking iron loss,main flux and cross flux saturation into account. The efficiencies of generalized model, control strategyand diagnostic procedure are illustrated with simulation results. Voir les détails
Mots clés : Wind energy conversion systems, fault detection and diagnosis, SEIG, Fractional-Order Controllers
Contribution to the Fault Diagnosis of a Doubly Fed Induction Generator for a Closed-loop Controlled Wind Turbine System Associated with a Two-level Energy Storage System
In this article, a contribution to the fault diagnosis of adoubly fed induction generator for a closed-loop controlled wind turbinesystem associated with a two-level energy storage system usingan on-line fault diagnostic technique is proposed. This technique isproposed to detect the rotor fault in the doubly fed induction generatorunder non-stationary conditions based on the spectral analysis of statorcurrents of the doubly fed induction generator by an adaptive fastFourier transform algorithm. Furthermore, to prevent system deterioration,a fractional-order controller with a simple design method isused for the control of the whole wind turbine system. The fractionalordercontroller ensures that the system is stable in both healthy andfaulty conditions. Additionally, to improve the production capacityunder wind speed fluctuations and grid demand changes, a two-levelenergy storage system consisting of a supercapacitor bank and leadacidbatteries is proposed. The obtained simulation results show thatthe objectives of the fault diagnosis procedure and control strategyare reached. Voir les détails
Mots clés : Wind energy conversion systems, adaptive Fast Fourier transform, doubly fed induction generator, fault detection and diagnosis, fractional-order control, two-level energy storage system
Modeling and Control of the Wind Energy Conversion Systems Based on DFIG Under Sub- and Super-Synchronous Operation Modes
In this work, the modeling and control of the Wind Energy Conversion Systems (WECS) based on doubly fed induction generator (DFIG) are presented. Firstly, we developed the models of the different elements of the conversion chain. After, we consider the vector control strategy of the active and reactive powers in order to ensure an optimum operation. Finally, the dynamic model of a DFIG and wind turbine grid connected system is determined in the dq-synchronous reference frame. The numerical simulation results obtained with Matlab/Simulink software present the behaviors of the sub-synchronous and super-synchronous operation modes. Voir les détails
Mots clés : wind power generation, doubly fed induction generator, renewable energy, modeling, control.
Properties of Co-doped ZnO thin films grown by pulsed laser deposition on glass substrates
Undoped and cobalt-doped zinc oxide (CZO) polycrystalline piezoelectric thin films (Co: 3,5 at.%) using a series of high quality ceramic targets have been deposited at 4501C ontoglass substrates using a pulsed laser deposition method. The used source was a KrFexcimer laser (248 nm, 25 ns, 2 J∕cm2). X-ray diffraction patterns showed that the Codoped ZnO films crystallize in a hexagonal wurtzite type structure with a strong (002) orientation, and the grain sizes calculated from these patterns decrease from 37 to 31 nmby increasing Co doping. The optical waveguiding properties of the films were characterized by using a prism-coupling method. The distinct M-lines of the guided transversemagnetic (TM) and transverse electric (TE) modes of the ZnO films waveguide have beenobserved. With the aim of study the optical properties of the ZnO films, an accuraterefractive index and thickness measurement apparatus was set up, which is called M-linesdevice. An evaluation of experimental uncertainty and calculation of the precision of therefractive index and thickness were developed on ZnO films. The optical transmittancespectra showed a good transparency in the visible region. Calculated optical band gapvarying from 3.23 to 3.37 eV when the content of Co doping increases from 0 to 5 at.%. Voir les détails
Mots clés : Thin films, ZnO, pulsed laser deposition, Piezoelectric, Waveguiding properties, Optical transmittance
Image-based Control for Cable-based Robots
Some human robot interactive applications involved in tele-robotics, remote supervisory andunmanned systems require specific capabilities. This demand has promoted various interactive modesand high-level control techniques such as tele-manipulation, speech, vision, gesture, etc. Among theseinteractive modes, the image based control which is often named point and click control has proven tobe the most appropriate one that offers multiple advantages. This mode consists of only and simplypointing in an appearing object of an image received from a remote site, to convert this click into a robotcommand towards the corresponding location in the real world space. This mode is suitable for remoteapplications, frees the human operator from being involved into the loop enabling him/her to usecommands in the sense of click and forget. This paper presents, firstly, the design and the realization ofan experimental planar cable-based robot constituted of four cables. Secondly, it presents the designand the implementation of a high-level image-based control. Some typical experiments which havebeen performed prove the simplicity and the effectiveness of the image-based control. Moreover, itopens perspectives for new applications with cable-based robots, particularity for rehabilitation applications. Voir les détails
Mots clés : Cable-based robot, human-robot interaction, image-based control, point and click, robot control.
Etude expérimentale et analyse probabiliste du comportement à la rupture en traction de composites verre-perlon-acrylique à usage orthopédique
Les effets de la nature des séquences de la stratification ainsi que les influences significatives du sens de découpe des échantillons par rapport au sens du flux de moulage sur le comportement mécanique en traction d’une série de matériaux composites stratifiés sont mises en évidence à partir d’une analyse de leurs propriétés mécaniques. Ces stratifiés à usage orthopédique et à base de résine acrylique renforcée de couches de fibres de verre et de perlon sont disposées selon trois différentes architectures. Une importante dispersion est observée sur les résultats de mesure du module de Young et des contraintes à la rupture. Ces dernières montrent des valeurs supérieures dans le sens perpendiculaire à celui du flux de moulage. La mesure de la fragilité, la caractérisation du comportement à la rupture de ces stratifiés ainsi que l’aspect probabiliste de cette dernière sont décrits quantitativement à partir de l’application du modèle probabiliste à deux paramètres de Weibull. Le caractère fragile de la rupture de ces stratifiés est ainsi traduit par les faibles valeurs mesurées des modules de Weibull. Un constat des principaux mécanismes responsables de la rupture est dressé à partir des observations microscopiques des faciès de rupture des éprouvettes rompues. Voir les détails
Mots clés : stratification, Fibre De Verre, Perlon, Dispersion, Module De Weibull
Effect Of Impurities On Microstructure And Structural Propertiesof The As-Cast And Treated Al-Zn
The microstructure of two Al-Zn alloys (with 10 and 30 wt.%Zn content) produced by melting in the high frequency induction furnace were investigated by means of scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD) analysisand themicrohardness tests. The results indicate that the presence of iron impurity causes the formation of eutectic (Al,Zn)3Fe in both alloys. The presence of the silicon impurity results in the formation of the phase separation in the Al-10%Zn as-cast alloy. The columnar to equiaxed transition was produced only in the Al-30%Zn as-cast alloy. The Vickers microhardness is higher in the equiaxed zone than in the columnar to equiaxed transition (CET) zone. The presence of iron causes intermetallic phase formation (Al, Fe, Si) 3,6Zn in the Al-30%Zn as-cast alloy enabling an increase in the lattice parameter. After a homogenization treatment, the microstructure of Al-Zn treated alloys consists only of αdendrites and stable eutectic phase. Voir les détails
Mots clés : Al-Zn, HF melting, Dendrites, CET, Impurities, Structural properties.
Allotropic transformation of cobalt in magnetic induction melted
In contrast to the abundance of studies in Fe -Al and Fe-Co, those in the Fe-Al-Co ternary system arescarce. Consequently, the phase separation and phase diagram of this system remain still ambiguous. Ternary Fe0.6Al1-x Cox(x values in a molar ratio of 0.05, 0.1, 0.15, and 0.2) have been elaborated by high frequency magnetic induction fusion, in order to study the effect of cobalt ternary addition on the structural behavior such as phase separation, thermal and mechanical properties of Fe-based alloy system, by means of x-ray diffraction, thermal analysis (DSC) and Vickers microhardness. An unexpected allotropic phase transformation from stable HCP to metastable FCC Cobalt has been observed in all alloys. Voir les détails
Mots clés : Fe-Al-Co, phase transformation, phase separation, lattice parameter.