Electrotechnique
Etude Comparative de la Compensation Active par Action Sélective par l’Approche FMV et Par la Théorie des Puissances Instantanées P-Q
This article presents a comparative study between two methods of active compensation by selective action of harmonics to minimize the total harmonic distortion factor (THD) of the current and voltage of the electric network, and consequently improve the power factor (PF). Both methods are based on the parallel active compensation of certain low frequency harmonics 5 and 7 which identification of the harmonics of references of the first method is through the approach the of Self Tuning Filter (STF) and the second is based on the theory of instantaneous power (P-Q). Selectively active compensation of harmonic current of the load 5 and 7 taken simultaneously Thereafter .The shapes of the signals and values of THD from the results of numerical simulations (Matlab/Simulink) developed demonstrates the efficiency and the best method of selectively active compensation. Voir les détails
Mots clés : PF, THD, Harmonics, Self Tuning Filter STF, Theory of Instantaneous Power PQ.
An Advanced Control Approach for a Shunt Selective Active Power Filter
This paper deals with the design, analysis andsimulation of a three phase three wire shunt selective active powerfilter. It compensates harmonic currents selectively underbalanced supply network. In order to improve, the factor ofpower of the network electric. An advanced control based on amulti-variable filter is adopted. The novelty with the controlapproach developed in this paper is to use a multi-variable filter,which can extract the harmonics of references of the load current,selectively according to the axis of Concordia (α-β). Generally theharmonic in questions are of low frequencies and order 5 and 7.The objective is that the current of the network doesn't containthe harmonics desired to filtered.The shapes of waves and thevalues of the THD of the network current before and after theselective active filtering of the harmonic 5 and 7 from of theresults of numerical simulations under the Matlab/Simulinkenvironment put in evidence the efficiency of this type of activefiltering elaborated. Voir les détails
Mots clés : harmonic, Shunt active power filter, multi-variable filter, THD
Performance evaluation of photovoltaic arrays subject to a Line-Ground fault
In this work, the effect of Line-to-Ground fault on the performance of photovoltaic (PV) arrays is analyzed. Due to the nature of their outdoor operation, PV arrays are subject to extreme weather conditions that affect their normal operation. The exposure of cables and junction boxes to such environmental conditions leads to different types of connection faults. Given that the frame of the PV panel is metallic, a short-circuit between the Line (positive charged wire) and the ground may occur frequently. A particle swarm optimization (PSO) based maximum power point tracking (MPPT) algorithm is then used to improve the efficiency of PV arrays. Simulation results show the large power loss caused by such type of fault and the effectiveness of the proposed approach in increasing the system's efficiency. Voir les détails
Mots clés : Photovoltaic (PV) arrays, Line-Ground fault, Particle Swarm Optimization (PSO), Maximum Power Point Tracking (MPPT)
Combination between STFT and DWT for Fault Detection and Diagnosis in Rotating Machinery by Vibration Monitoring
Signal analysis with fixed time-frequency resolution, such as the Short-Time Fourier Transform(STFT), is a common tool for many industrial applications in rotating machinery condition monitoring allowing effective implementation via the Fast Fourier Transform (FFT).However, the fixed time-frequency resolution of the STFT can lead to the undesirable smearing of events in both timeand frequency. In this paper, we propose a combination between STFT and DWT for the faults detection and diagnosis in a rotating machine. An implementation procedure for the fault detection and diagnosis in rotating machinery at real-time has been presented out in this paper. The experimental results confirm that this procedure serves as a good tool to fault detection and diagnosis in rotating machinery. Voir les détails
Mots clés : I. Atoui, R. Boulkroune, A. Grid, and R. Saidi
Modelling, Faults Detection and Diagnosis of Squirrel-Cage Self Excited Induction Generator for Isolated Wind Energy Conversion System
The condition monitoring of the Squirrel-cage Self-Excited Induction Generator (SEIG). can significantly reduce the costs of maintenance, prevent the unscheduled downtimes and make the best maintenance decisions for isolated Wind Energy Conversion Systems (WECS). On the other hand, growing attention has been paid to fractional calculus theory in practical control field for many industrial applications. In this paper, an on-line diagnostic procedure for stator and rotor faults in the squirrel SEIG of isolated wind energy conversion system is presented. This diagnostic procedure is based on stator current analysis by FFT. A generalized model of the squirrel-cage SEIG is developed to simulate both the rotor and stator faults taking iron loss, cross flux saturation into account. Additionally, a new control strategy is proposed for the fixed operation of the wind turbine, based on fractional PIλ controllers. Voir les détails
Mots clés : Issam Attoui, Amar Omeiri
FAULT DETECTION AND DIAGNOSIS IN ROTATING MACHINERY BY VIBRATION MONITORING USING FFT AND WAVELET TECHNIQUES
Rotor unbalance is the most cause of machine vibration that reduces the life of the rotating machine. On the other hand, vibration monitoring is reported as an interesting technique for the rotating machinery condition diagnosis.This paper considers the Wavelet Transform (WT) and FFT of vibration signals for detect and diagnose of unbalance faults in rotating machinery. The fault condition and location of faults are success fully detected by WT-FFT for non-stationary vibration measurements obtained from accelerometer sensors. Experimental studies on the rotating machine include faulty rotor with different rotational speeds has been carried out in this paper. These experimental results confirm that WT-FFT serves as a good tool to online faults detection and diagnosis of rotating machines. Voir les détails
Mots clés : Rotor unbalance, fault detection and diagnosis, Rotating machinery, WAVELET TECHNIQUES
Contrôle des Transits de Puissance par l’Utilisation d’un UPFC Connecté à une Ligne de Transmission
The FACTS technologies involve conversion andswitching of power electronics in the range of a few tens to few hundred megawatts. The new state devices such as MOSFETs, IGBTs, GTOs and also other suitable power electronic devices are used as controlled switches in FACTS devices. The universal and most flexible FACTS device is the Unified Power Flow Controller “UPFC”, this device is the combination of three compensators characteristic; i.e., impedance, voltage magnitude and phase angle, that are able to produce a more complete compensation [1]. Voir les détails
Mots clés : FACTS, MOSFETs, IGBTs, GTOs, UPFC
Etude de la Performance d’un Dispositif STATCOM Utilisée pour Compenser la Puissance Réactive au Point de Raccordement
The industrial extension during the last decades led to increasing considerable requirements in the electric power, in spite of the significant energy production.The FACTS concept “Flexible Alternative Current Transmission Systems” regroups all devices to basis of electronics of power that permits to improve the exploitation of the electric network. The technology of these systems “static switches” assure a speed superior to the one of the classic electromechanical systems.The objective of this paper is to study the functions of control offered by the STATCOM “STATic COMpensator” in the regulation of the voltage by compensation of the reactive energy. Voir les détails
Mots clés : FACTS, static switches, STATCOM
Real Time Implementation of Shunt Active PowerFilter (SAPF)for Harmonic suppression and PowerQuality Improvement
In this paper, A Shunt Active Power Filter (SAPF) is implemented using a dSPACEDS1104 processor to compensate harmonics and reactive power produced by nonlinearload. The reference source current is computed based on the measurement of harmonicsin the supply voltage and load current. A hysteresis based current controller has beenimplemented in a DSP processor for injecting the compensating current into the powersystem, so that SAPF allows suppression of the harmonics and reactive power componentof load current, resulting in a supply current that is purely sinusoidal. Simulation andexperimental results of the proposed SAPF to meet the IEEE-519 standards are presented. Voir les détails
Mots clés : Harmonics, Power quality, Active power filter, hystérisis comparator, real time control
L’OPTIMISATION DE LA VITESSE DE SOUDAGE ELECTRIQUE A L’ARC PAR MODELISATION NUMERIQUE
Le procédé de soudage à l’arc électrique sous flux solide [1], est l’un des procédé de soudage le plus répondu dans l’industrie, il est conditionné par une variante de paramètres telle que la tension de soudage, le courant de soudage et la vitesse de soudage dans ce travail nous nous somme concentré à donner une idée claire sur les conséquences de la variation de la vitesse de soudage dans ce procédé par le biais d’une étude numérique pour différentes valeurs de vitesse cette étude peut contribué à définir la valeur optimale de la vitesse de soudage adéquate lors de l’usage de ce procédé. L’élément soudé choisi dans notre cas est les deux bouts sphériques constituant la bouteille à gaz B13 fabriqué par l’entreprise SNS BAG Batna. [1-2]. La formulation de la théorie physique et métallurgique du soudage à guidé notre raisonnement numérique à déduire le choix optimale de la vitesse de soudage de plus elle nous montre la délimitation de la Zone Affectée Thermiquement dite (ZAT) et nous propose un suivi de température en tout point des deux bouts soudées au cours du soudage. Voir les détails
Mots clés : Soudage électrique– vitesse de soudage –– numérique