Electrotechnique
Conception et commande d'une machine de soudage de type TIG
TIG welding machine are higly used in mostof industries.this work consists of the desing and engineering of a welding machine. Voir les détails
Mots clés : arc welding, TIG generator, DC/DC convertor
Amélioration de la Qualité du Réseau Electrique à l’Aide deCompensateurs Actifs
This thesis falls within the framework of harmonic depollution of the low voltage electrical networks usingan active power compensators, this pollution is caused by the unlimited use of non-linear loads. The causes, theeffects of these harmonic disturbances and the international standards imposed to protect the consumers againstthese disturbances are presented. Also, several traditional and modern solutions against the harmonic pollution arepresented. We have focused our study on the development of the control techniques of shunt active power filter, Forthis reason, we have based on the development of methods for determining harmonic reference currents based on amultivariable filter (MVF), These new methods are able to correctly extract the reference harmonic currentsnecessary to control the SAPF, after that, we have implemented the modified (p-q) method on the power active filterin order to carry out a global active compensation of the harmonics currents, the behavior and quality of filtering ofthe APF are evaluated with two kinds of electric loads, with different types of electrical network and with aphotovoltaic power source. Then, we have developed two harmonic selective identification methods based onmultivariable filter, which are implemented in real time, in order to realise a selective active compensation ofspecific harmonic currents under low DC link voltage, this work was closed by an experimental validation of anactive power filter (APF) fed by a PMSG-based wind system, for this we implemented three controllers to controlthis system, which are the predictive current controller, Type-2 fuzzy logic controller, and an ANFIS controller. Theexperimental results obtained show that this system is capable of compensating for harmonics and reactive power,and also injected active power into the electrical network. Voir les détails
Mots clés : Harmonic pollution, APF, MVF, global active filter, selective active filter, wind system, PMSG
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
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)
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
Detection of Broken Rotor Bar Fault in 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. The 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, wavelet paket, analyses
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
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
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)
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