Electrotechnique
Modélisation électromagnétique d’un système de contrôle non destructif par courant de Foucault
Nous avons étudié dans ce mémoire un modèle électromagnétique du contrôle non destructif par courant de Foucault d’un système sonde-pièce d’une géométrie 2D axisymétrique. Notre recherche bibliographique étendue, nous a permis de consulter assez de modèles physiques récents, ainsi que les méthodes numériques exploitées dans la résolution de la formulation magnétodynamique en régime fréquentiel. Pour notre cas, on a opté pour l’application champ magnétique du module AC/DC de COMSOL à la base des éléments finis, à fin de calculer le potentiel vecteur magnétique azimutal représentant une variable principale pour la détermination de toutes les autres grandeurs électromagnétiques et électriques du système. Partant d’une source d’excitation sinusoïdale du capteur placé à proximité d’une pièce à matériau conducteur, on est arrivé au calcul de la variation d’impédance aux bornes du capteur. Cette grandeur électrique, résultante de la topologie de perturbation des lignes de courant de Foucault, nous informe sur l’existence des défauts à la surface de la pièce. Expérimentalement, nous avons pratiqué un balayage de la sonde sur une pièce à deux défauts distants et de profondeur différente, l’impédance mesurée est plus grande lorsque le défaut est plus profond. Ces résultats ont été comparés avec ceux obtenus numériquement, et l’erreur relative a été de l’ordre 3%. Voir les détails
Mots clés : contrôle non destructif, Courant de Foucault, Électromagnétisme, méthode des éléments finis, Impédance d’un capteur, Défauts.
DETECTION OF BROKEN ROTOR BAR FAULT IN THE SQUIRREL CAGE INDUCTION MOTOR USING WAVELET PACKET ANALYSIS
The fault of broken rotor bars in a three phase induction motor is diagnosed by using the wavelet Packet analysis. In this paper Daubechies wavelet is selected as the wavelet base and the wavelet coefficient is obtained from the wavelet transform of current signal of the faulty induction motor. Tghe energy of wavelet components appear to be useful for detecting different electrical faults. In this paper we will study the problem of broken rotor bars Voir les détails
Mots clés : Wavelet Packet, Analysis, diagnosis fault, induction motor, broken bar
Sensor Monitoring of the Concentrations of Different Gases Present in Synthesis of Ammonia Based On Multi-Scale Entropy and Multivariate Statistics
This paper presents powerful techniques for the development of a new monitoring method based on multi-scale entropy (MSE) in order to characterize the behaviour of the concentrations of different gases present in the synthesis of Ammonia and soft-sensor based on Principal Component Analysis (PCA). Voir les détails
Mots clés : Ammonia synthesis, Concentrations of different gases, Soft sensor, Multi-scale entropy, multivariate statistics.
Evaluating the Flicker caused byElectric Arc Furnacethrough the Multi-scale Entropy MSE Algorithm SampEn
This paper presents a new method to evaluate the Arc voltage quality in electric arc furnace (EAF). It has been shown that is possible to allow the representation of nonlinear dynamics and coupling effects between different waves for irregularity of electrical signals issued by electrical components though multi-scale entropy algorithm SampEn. This work shows the behavior of the feature extraction with SampEn when it’s used to evaluate the signals that deviate the arc voltage in (EAF). Flicker effect with voltage imbalances are analyzed by means of the SampEn concept. Voir les détails
Mots clés : Entropy, Arc voltage signals quality, Flicker effect, voltage imbalance
Improving the Power Quality of the Arc WeldingSupply using an Active Power Filter
This paper presents a new circuit topology suitablefor arc welding inverter applications, this topology is based onshunt active power filter (APF), in order to improve the powerquality and reduced the total harmonic distortion (THD) byconsequently improve the power factor (PF), a modified activeand reactive power method (p-q),which is combined with aself-tuning filter, is used to identify the harmonics currentsreferences of the load current, Also a PI controller has beenused to maintain the level of DC-link voltage at a constantvalue and improves its dynamic response; the voltage sourceinverter of APF is controlled by hysteresis current controller.The Major favorable features of this topology like fastresponse to load and source voltage conditions will result inbetter welding performance. The performance of the entiresystem is evaluated on the basis of THD of the source current,input power factor, dynamic response, voltage regulation androbustness to prove its effectiveness in terms of excellent powerquality. Voir les détails
Mots clés : arc welding, Active power filter (APF), power factor (PF), total harmonic distortion (THD), modified active and reactive method (p-q)
Analysis and Simulation in Electrical Networks Using SSSC Device for Damping Power Oscillations
A large power system has many interconnections and bulk power transmissions over long distance. As a result, there low frequency inter-zone oscillations which make the system vulnerable to cascade failures. Many different methods have been proposed to alleviate the oscillations in the power system. For many years, Power System Stabilizer (PSS) has been one of the devices traditionally used to dampen oscillations. It is reported that during some operating conditions, PSS may not effectively attenuate oscillations; for this reason, other effective alternatives are required in addition to PSSs. On the other hand, the advent of FACTS has led to a new and more versatile approach to controlling the power system in a desired way. These devices based on very advanced power electronics components (GTO, IGBT,…). FACTS devices according to their network connection are distinguished countervailing series, shunt and hybrid such as: SSSC, ASVC and IPFC, respectively. One of the best-innovated Flexible AC Transmission System devices is the Static Synchronous Series Compensator. The purpose of this paper is to study the control functions provided by the SSSC in controlling the power flow of the load capacity of power lines. Voir les détails
Mots clés : PSS, FACTS, GTO, IGBT, SSSC, ASVC, IPFC
Fault-tolerant power extraction strategy for photovoltaic energy systems
Photovoltaic (PV) arrays are subject to various types of environmental disturbances and component-related faults that affect their normal operation and result in a considerable energy loss. The nonlinear current-voltage (I-V) characteristic curve of the PV array prevents the detection and isolation of the faults and also makes the tracking of the maximum power operating point (MPP) more difficult. Fault detection and identification (FDI) techniques have been proposed to detect the presence of faults and isolate them. Many maximum power point tracking (MPPT) methods have been proposed to find the best operating point in the presence of disturbed environmental conditions. However, existing FDI methods do not consider the tracking of the MPP in faulted operating conditions, and available MPP tracking methods do not consider the occurrence of faults in the PV system. The objective of this study is to propose a fault-tolerant control (FTC) strategy to detect the presence of abnormal operating conditions and reconfigure the MPPT procedure to search for the new suboptimal operating point. The FDI method is based on monitoring the PV panel generated power for the presence of abrupt changes; the MPPT reconfiguration is based on a combination between Incremental Conductance (IncCond) Algorithm and an Improved Current-based Particle Swarm Optimization (ICPSO) tracking technique. Simulation and experimental results show an excellent performance of the proposed FTC method in the presence of various types of faults. Voir les détails
Mots clés : Fault-tolerant control (FTC), Particle swarm optimisation (PSO), Photovoltaic (PV) arrays, Line-Ground fault, Line-line fault, Partial shading, Maximum Power Point Tracking (MPPT)
A Fuzzy Logic Based Approach for the monitoringof Open Switch Fault in a SVM Voltage SourceInverter fed Induction Motor Drive
The reliability of power electronics system such as three phase inverter is important in many industrial processes. The monitoring in industrial systems represents an important economic objective. To guarantee the safety and the continuity in production, exploitation and to record the useful events with the feedback experience for the curative maintenance. One of the possible faults that occur in inverter is the open switch fault. The cost of this schedule can be high, and this justifies the development of fault diagnostic methods.In this work we present a reliable strategy for monitoring and detection of open switch in Space Vector Modulation of voltage source inverter (SVM-VSI) faults using the fuzzy logic approach. The principle of the suggested approach strategy is based on the acquisition of stator currents, to calculate the average absolute values of currents (AAVC), which allows the real-time detection and localization of inverter IGBT open-circuit faults using just the motor phase currents. A model of the system is built using MATLAB/SIMULINK. Simulation results are presented showing the monitoring approach performance under distinct operating conditions. Voir les détails
Mots clés : Monitoring, Detection, fault inverter, SVM, VSI, AAVC
PREDICTIVE CONTROL OF PERMANENT MAGNET SYNCHRONOUS MACHINE USED IN A WIND SYSTEM
The use of renewable energy systems has become very important in the re-cent years due to environmental concern and the increasing demand of energy. Nowadays, wind power is the fastest growing energy source with increase in installed power mainly driven by increase in quantity and power rating of the wind turbines. The increase in the power of the generators leads to the need of research on new control strategies and different topologies of power converters to combine performance, power quality and efficiency demanded by these sys-tems.In this sense, this research project presents various advanced predictive control strategies for different power electronic converters employed in perma-nent magnet synchronous generator (PMSG) wind energy systems. The pro-posed systems combine the advantages of proven wind turbine technologies, such as low-cost machine-side converters, and efficient grid-side converters. The classical control techniques, based on linear PI regulators and low band-width modulation, present several technical issues during system operation, to overcome these issues, a high performance predictive control strategies are proposed in this thesis to control the power converters. The main feature of these control techniques are that a particular attention is paid to increase the efficiency and sustainability, reduce the torque and DC-link ripples, operating at considerably constant switching frequency and help higher penetration of renewable fluctuating power into the grid. Detailed technical work is supported by MATLAB/SIMULINK model based simulations and validated by experi-mental work on a laboratory prototype consisting in a PMSG and power con-verters, considering the fluctuation of the wind speed. Voir les détails
Mots clés : Permanent Magnet Synchronous Generator (PMSG), Wind energy systems, Predictive control stratigies, Experimental work
Design and real time implementation of sliding mode supervised fractionalcontroller for wind energy conversion system under sever working conditions
Wind energy conversion system (WECS) is increasingly taking the place to be the most promised renewablesource of energy, which obliges researchers to look for e?ective control with low cost. Thus, this paper proposesto build a suitable controller for speed control loop to reach the maximum power point of the wind turbine undersever conditions and to ensure the stability of the outer voltage regulation loop to meet high range of loadvariations. In literature, a major defect of the well-used conventional PI controller is the slow response time andthe high damping. Nowadays, intelligent controllers have been used to solve the drawbacks of the conventionalones but they demand high speed calculators and expensive cost. Moreover, many solutions proposed thefractional order PI controller (FO-PI) by extending the order of integration from integer to real order. The FO-PIcontroller presents also some weakness in steady state caused by the approximation methods. The idea of thispaper is to propose a Sliding Mode Supervised Fractional order controller (SMSF) which consists of conventionalPI controller, FO-PI controller and sliding mode supervisor (SMS) that employs one of the controllers to ensuregood steady and transient states. WECS laboratory prototype is built around real-time dSPACE cards andevaluated to verify the validity of the developed SMSF. The results clearly ful?ll the requirements, con?rm itshigh performance in steady and transient states and demonstrate its feasibility and e?ectiveness. Voir les détails
Mots clés : Maximum Power Point Tracking (MPPT), Wind Energy Conversion System (WECS), PI controller, Fractional order PI controller, Sliding mode control, Direct power control