Réglage des puissances active et réactive d'un aérogénérateur par les techniques intelligences artificielles

The work presented in this thesis focuses on the study, analysis, and design of full control of a variable-pitch wind system (VPWS) based on a doubly fed induction generator (DFIG) fed by a direct matrix converter (DMC) equipped with a damped RLC passive filter to reduce the injection of harmonics into the grid. In this context, to ensure optimal exploitation of wind energy, the maximum power point tracking (MPPT) strategy has been designed when the wind speed is lower than its nominal value on the one hand, and on the other hand, to limit the power extracted to its rated value and also avoid malfunctioning of the wind system when the wind speed is exceeded its nominal value, the pitch angle control strategy has been applied. For a high-performance control of the active and reactive powers of DFIG under the stochastic variation of the wind speed conditions, several control strategies based on the theory of sliding modes like the first order controller (F-OSMC), second order (S-OSMC) and the third (TOSMC) have been incorporated into the direct flied-oriented control (DFOC) strategy. Moreover, to ensure direct energy conversion between the grid and the DFIG without a DClink, a direct matrix converter controlled by the Venturini modulation strategy has been used. In this context, to minimize the total current harmonic distortion (THD), a damped RLC filter that consists of a resistor connected in parallel with an inductor was installed between the grid and DMC. This type of filter meets the proposed conversion system's technical requirements and has a simpler structure, cheaper cost, and more profitable. The different control strategies proposed for the system considered were simulated in the Matlab environment. The obtained results confirm the effectiveness and reliability of these strategies regarding the decoupled control of active and reactive powers, the good monitoring of the imposed references against the stochastic variation of the wind speed, the low weather response, and the reduced harmonic distortion rat

Biocontrol of Wheat Fusarium Crown and Root Rot by Trichoderma spp. and Evaluation of Their Cell Wall Degrading Enzymes Activities

Fourteen strains of Trichoderma spp. were isolated from Algerian desert soils and assessed for their antagonistic activity against Fusarium crown and root rot of wheat. Biocontrol efficiency of Trichoderma spp. was studied by in vitro and in vivo based bioassay against three pathogenic species: F. culmorum, F. graminearum and F. verticillioides. In vitro based bioassay (dual culture) results obtained with all Trichoderma spp. isolates showed significant decrease in colony diameter of Fusarium species compared to the control. The highest percentages of reduction in colony diameter were obtained with T. harzianum Thr.4 causing a growth reduction of 70.68%, 67.05 and 70.57% against F. culmorum, F. graminearum and F. verticillioides, respectively. All Trichoderma spp. isolates were able to overgrow and sporulate above F. culmorum colonies but no overgrowth was observed with F. graminearum and F. verticilliodes. The seed treatment by Trichoderma spp. isolates before sowing in a soil already infested by the pathogens led to a significant decrease of disease severity compared to the untreated control. The highest disease index decrease (>70%) was obtained with two isolates of T. harzianum (Thr.4 and Thr.10) and T. viride Tv.6 against the three fungal pathogens. Lytic enzymes production by Trichoderma spp. isolates was tested in liquid cultures containing fungal cell walls of each pathogen as sole carbon source. Higher levels of protease and chitinase activities were induced by hyphal cell walls of F. graminearum than cell walls of F. verticillioides and F. culmorum. T. harzianum Thr.4 exhibited the highest enzyme activities with hyphal cell walls of F. graminearum and F. culmorum. However, in the medium amended with cell wall of F. verticillioides, maximal lytic activities were recorded for T. viride Tv.6

Direct torque control based on second order sliding mode controller for three-level inverter-fed permanent magnet synchronous motor: comparative study

Introduction. The permanent magnet synchronous motor (PMSM) has occupied a large area in the industry because of various benefits such as its simple structure, reduced moment of inertia, and quick dynamic response. Several control techniques have been introduced for the control of the PMSM. The direct torque control strategy associated to three-level clamped neutral point inverter has been proven its effectiveness to solve problems of ripples in both electromagnetic torque and stator flux with regard to its significant advantages in terms of fast torque response. Purpose. The use of a proportional integral speed controller in the direct torque control model results in a loss of decoupling with regard to parameter fluctuations (such as a change in stator resistance value induced by an increase in motor temperature), which is a significant drawback for this method at high running speeds. Methods. That is way a second order sliding mode controller based on the super twisting algorithm (STA) was implemented instead of PI controller to achieve a decoupled control with higher performance and to insure stability while dealing with parameter changes and external disturbances. Results. The simulation results carried out using MATLAB/Simulink software show that the model of direct torque control based on a three-level inverter-fed permanent magnet synchronous motor drive has better performance with second order sliding mode speed controller than the proportional integral controller. Through the response characteristics we see greater performance in terms of response time and reference tracking without overshoots. Decoupling, stability, and convergence toward equilibrium are all guaranteed.Вступ. Синхронний двигун з постійними магнітами (СДПМ) зайняв велике місце в промисловості завдяки різним перевагам, таким як його проста конструкція, зменшений момент інерції та швидкий динамічний відгук. Для керування СДПМ було введено декілька методів керування. Стратегія прямого управління крутним моментом, пов'язана з трирівневим інвертором з фіксованою нейтральною точкою, довела свою ефективність для вирішення проблем пульсацій як електромагнітного крутного моменту, так і магнітного потоку статора, враховуючи його значні переваги з точки зору швидкої реакції крутного моменту. Мета. Використання пропорційно-інтегрального регулятора швидкості моделі прямого управління крутним моментом призводить до втрати розв'язки по відношенню до коливань параметрів (таких як зміна значення опору статора, викликане підвищенням температури двигуна), що є істотним недоліком для цієї моделі на високих робочих швидкостях. Методи. Таким чином, замість ПІ-регулятора був реалізований ковзний регулятор другого порядку, заснований на алгоритмі суперскручування (STA), для досягнення розв'язаного управління з більш високою продуктивністю та забезпечення стабільності при роботі зі змінами параметрів та зовнішніми збуреннями. Результати моделювання, виконаного з використанням програмного забезпечення MATLAB/Simulink, показують, що модель прямого керування крутним моментом, заснована на трирівневому приводі синхронного двигуна з постійними магнітами з інверторним живленням, має кращу ефективність з регулятором швидкості з ковзним режимом другого порядку, ніж пропорційний інтегральний контролер. Завдяки характеристикам відгуку бачимо більш високу ефективність з точки зору часу відгуку та відстеження посилань без перерегулювання. Розв'язка, стабільність та збіжність до рівноваги гарантовані

NONLINEAR FEEDBACK APPROACH BASED ON SLIDING MODE CONTROLLER FOR AN INDUCTION MOTOR FED BY MATRIX CONVERTER

In this paper, a nonlinear feedback linearization approach and sliding mode controller are combined to generate the reference voltages for a matrix converter controlled by DSVM strategy fed induction motor in order to preserve the robustness with respect to desired dynamic behaviors for this drive system. The transfer function and the selection approach of the parameter for the input filter are also introduced. The simulation results of the robustness testing of the drive system have been carried out to validate the advantages of the proposed control system

Telescopic Op-Amp Optimization for MDAC Circuit Design

An 8-bit 40-MS/s low power Multiplying Digital-to-Analog Converter (MDAC) for a pipelined-to-Analog to Digital converter (ADC) is presented. The conventional dedicated operational amplifier (Op-Amp) is performed by using telescopic architecture that features low power and less-area. Further reduction of power and area is achieved by using multifunction 1.5bit/stage MDAC architecture. The design of the Op-Amp is performed by the elaboration of a program based on multi objective genetic algorithms to allow automated optimization. The proposed program is used to find the optimal transistors sizes (length and width) in order to obtain the best Op-Amp performances for the MDAC. In this study, six performances are considered, direct current gain, unity-gain bandwidth, phase margin, power consumption, area, slew rate, thermal noise, and signal to noise ratio. The Matlab optimization toolbox is used to implement the program. Simulations were performed by using Cadence Virtuoso Spectre circuit simulator in standard AMS 0.18μm CMOS technology. A good agreement is observed between the results obtained by the program optimization and simulation, after that the Op-Amp is introduced in the MDAC circuit to extract its performances

Parameter Extraction of Schottky Solar Cell in Wide Temperature Range Using Genetic Algorithms

This paper proposes a new method based on a genetic algorithm (GA) approach to optimize the electrical parameters such as height barrier, ideality factor, fill factor, open-circuit voltage and power conversion efficiency, in order to improve the electrical performance of Schottky solar cells in an over wide range of temperature. Thus the parameters research process called objective function is used to find the optimal electrical parameters providing greater conversion efficiency. The proposed model results are also compared to experimental and analytical I-V data, where a good agreement has been found between them. Therefore, this approach may provide a theoretical basis and physical insights for Schottky solar cells

Enhancing Solar Cell Conversion Efficiency Through Evolutionary Optimization Using Genetic Algorithms

In this study, we propose a new method based on genetic algorithms to optimize the performance of intermediate-band solar cells (IBSC). Our approach aims to maximize photovoltaic conversion efficiency by judiciously optimizing the geometric and physical parameters of the IBSC structure., which must be partially filled. This filling ensures the presence of both empty states in the intermediate band (IB) to receive electrons from the valence band (VB), and filled states to provide electrons to the conduction band (CB). Recently, studies have observed the effect of IB occupancy on cell efficiency, and calculated the optimal efficiency for IB devices. The analytical expression for optimal IB filling has been utilized for different scenarios involving IB-CB coupling strength and IB region width. In this work we have studied the influence of the intermediate band energy level, the effects of doping on efficiency, short-circuit current, open-circuit voltage, fill factor, and in order to validate our approach on parasitic effects such as series and shunt resistance

EDAPHIC FACTORS AFFECTING DISTRIBUTION OF SOIL FUNGI IN THREE CHOTTS LOCATED IN ALGERIAN DESERT

ABSTRACTA total of 327 colonies of fungi were isolated from three chotts located in the Northeast of Algerian Sahara (Chott Merouane,Melghir and Tighdidine). Twenty eight species representing thirteen genera were recorded in Chott Merouane, twenty twospecies representing eleven genera were isolated from Chott Melghir and twenty five species corresponding to eleven generawere recorded in Chott Tighdidine. The most common genera were Aspergillus, Penicillium and Cladosporium. Statisticalanalysis revealed a significant positive correlation between fungal population and number of edaphic factors, especiallyorganic carbon and nitrogen contents. Fungal population showed negative correlation with chloride and sodium. The mostspecies isolated in this study were melanized fungi.KEYWORDS: Fungi, distribution, hypersaline soil, edaphic factors.RESUMETrois cent vint sept colonies de champignons filamenteux sont isolées à partir de trois chotts localisés dans le Nord-est duSahara Algerien (Chott Merouane, Melghir and Tighdidine). Vingt-huit espèces de 13 genres ont été isolées de ChottMerouane. Vingt-deux espèces de 11 genres ont été isolées de Chott Melghir et vingt-cinq espèces correspondant à 11 genresont été obtenues de Chott Tighdidine. Les genres les plus abondants sont Aspergillus, Penicillium et Cladosporium. L'analysestatistique a révélé une corrélation positive significative entre la densité de la population fongique et un nombre des facteursédaphiques, en particulier la teneur en carbone organique et l’azote. La densité de la population fongique a montré unecorrélation négative avec la teneur de chlorure et de sodium.MOTS CLES: Champignons filamenteux, distribution, sol hypersalin, facteurs édaphiques

Identification and characterization of MUS81 point mutations that abolish interaction with the SLX4 scaffold protein

AbstractMUS81-EME1 is a conserved structure-selective endonuclease with a preference for branched DNA substrates in vitro that correspond to intermediates of DNA repair. Cells lacking MUS81 or EME1 show defects in the repair of DNA interstrand crosslinks (ICL) resulting in hypersensitivity to agents such as mitomycin C. In metazoans, a proportion of cellular MUS81-EME1 binds the SLX4 scaffold protein, which is itself instrumental for ICL repair. It was previously reported that mutations in SLX4 that abolished interaction with MUS81 affected ICL repair in human cells but not in murine cells. In this study we looked the other way around by pinpointing amino acid residues in MUS81 that when mutated abolish the interaction with SLX4. These mutations fully rescued the mitomycin C hypersensitivity of MUS81 knockout murine cells, but they were unable to rescue the sensitivity of two different human cell lines defective in MUS81. These data support an SLX4-dependent role for MUS81 in the repair, but not the induction of ICL-induced double-strand breaks. This study sheds light on the extent to which MUS81 function in ICL repair requires interaction with SLX4

Design of a Selective Smart Gas Sensor Based on ANN-FL Hybrid Modeling

The selectivity is one of the main challenges to develop a gas sensor, the good chemical species detection in a gaseous mixture decreasing the missed detections. The present paper proposes a new solution for gas sensor selectivity based on artificial neural networks (ANNs) and fuzzy logic (FL) algorithm. We first use ANNs to develop a gas sensor model in order to accurately express its behavior. In a second step, the FL and Matlab environment are used to create a database for a selective model, where the response of this one only depends on one chemical species. Analytical models for the gas sensor and its selective model are implemented into a Performance Simulation Program with Integrated Circuit Emphasis (PSPICE) simulator as an electrical circuit in order to prove the similarity of the analytical model output with that of the MQ-9 gas sensor where the output of the selective model only depends on one gas. Our results indicate the capability of the ANN-FL hybrid modeling for an accurate sensing analysis