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There has always been a high expectation that wind generation systems would capture maximum power and integrate properly with the grid. Utilizing a wind generation system with increased management to meet the growing electricity demand is a clever way of accomplishing this. However, wind power generation systems require a sophisticated, unique, and dependable control mechanism in order to achieve stability and efficiency. To improve the operation of the wind energy conversion method, researchers are continually addressing the obstacles that presently exist. Therefore, it is necessary to know which control can improve the whole system’s performance and ensure its successful integration into the network, despite the variable conductions. This article examines wind turbine control system techniques and controller trends related to the permanent magnet synchronous generator. It presents an overview of the most popular control strategies that have been used to control the PMSG wind power conversion system. Among others, we mention nonlinear sliding mode, direct power, backstepping and predictive currents control. First, a description of each control is presented, followed by a simulation performed in the Matlab/Simulink environment to evaluate the performance of each control in terms of reference tracking, response time, stability and the quality of the signal delivered to the network under variable wind conditions. Finally, to get a clear idea of the effect of each control, this work was concluded with a comparative study of the four controls.

Wind Turbine (WT)-based Doubly-Fed Induction Generator (DFIG) is a nonlinear system, in which the wind has variable behavior, and the local reactive power depends on the random demand of the AC grid; all these make conventional controls insufficient for an adequate power output. Thus, a new direct power control (DPC) strategy is proposed in this paper, to force the system to track the desired dynamics with higher performance and less drawbacks. This new approach is based on machine learning, Neural-Network- and Neuro-Fuzzy-DPC (NN- and NF-DPC), both are designed to overcome the problems related to power control, wind and local reactive power variations. All operating modes (sub-synchronous, super-synchronous and synchronous modes), with the possibility of local reactive power compensation are considered in this paper. Both NN and NF networks have been trained under the MATLAB interface. The trained NF showed better efficiency than the NN; the learning time is reduced to a few seconds with less computational effort, and less complexity. The effectiveness of both controls has been confirmed through simulation tests using MATLAB software. The obtained results have shown that the NF-DPC strategy presents better performances than NN-DPC and conventional control, with fast response, robustness, less power ripples and reduced Total Harmonic Distortion (THD) in the generated currents.

The Department of Energy’s High Temperature, Low Relative Humidity Membrane Program was begun in 2006 with the Florida Solar Energy Center (FSEC) as the lead organization. During the first three years of the program, FSEC was tasked with developing non-Nafion® proton exchange membranes with improved conductivity for fuel cells. Additionally, FSEC was responsible for developing protocols for the measurement of in-plane conductivity, providing conductivity measurements for the other funded teams, developing a method for through-plane conductivity and organizing and holding semiannual meetings of the High Temperature Membrane Working Group (HTMWG). The FSEC membrane research focused on the development of supported poly[perfluorosulfonic acid] (PFSA) – Teflon membranes and a hydrocarbon membrane, sulfonated poly(ether ether ketone). The fourth generation of the PFSA membrane (designated FSEC-4) came close to, but did not meet, the Go/No-Go milestone of 0.1 S/cm at 50% relative humidity at 120 °C. In-plane conductivity of membranes provided by the funded teams was measured and reported to the teams and DOE. Late in the third year of the program, DOE used this data and other factors to decide upon the teams to continue in the program. The teams that continued provided promising membranes to FSEC for development of membrane electrodemore » assemblies (MEAs) that could be tested in an operating fuel cell. FSEC worked closely with each team to provide customized support. A logic flow chart was developed and discussed before MEA fabrication or any testing began. Of the five teams supported, by the end of the project, membranes from two of the teams were easily manufactured into MEAs and successfully characterized for performance. One of these teams exceeded performance targets, while the other requires further optimization. An additional team developed a membrane that shows great promise for significantly reducing membrane costs and increasing membrane lifetime.« less

A novel direct reactive power control strategy based on the three-level inverter topology (DRPC-3N) is proposed for a doubly fed induction generator (DFIG)-based wind power plant system. The robustness against parametric variations and control performances of the presented methodology are analyzed under random wind speeds, taking into account the effect of the heating of the windings as well as the saturation of the magnetic circuit. The performance indices include obtaining a sinusoidal AC-generated current with low THD and less ripples in the output. Moreover, the generator can be considered as a reactive power compensator, which allows for the controlling of the active and reactive power of the stator side connected directly to the grid side using only the rotor converter. In this study, unpredictable conduct of the wind velocity that forces the DFIG to operate through all modes of operation in a continual and successive way is considered. The received wind power is utilized to extract the optimum power by using an appropriate MPPT algorithm, and the pitch angle control is activated during the overspeed to restrict the produced active power. The simulation tests are performed under Matlab/Simulink and the presented results show the robustness and effectiveness of the new DRPC strategy with the proposed topology, which means that the performances are more sophisticated.

Currently conventional sources like coal, petroleum and natural gas meet the energy requirements of developing and undeveloped countries. Over a period of time there is high risk of these energy sources getting depleted. Hence an alternate source of energy i.e. renewable energy is the need of the hour. The advantages of renewable energy like higher sustainability, lesser maintenance, low cost of operation, and minimal impact on the environment make the role of renewable energy sources significant. Out of the various renewable energy sources like solar energy, wind energy, hydropower, biogas, tidal and geothermal, usage of solar energy is gradually increasing. Among various solar energy sources, Photovoltaics has dominated over the past two decades since it is free clean energy and availability of abundant sunlight on earth. Over the past few decades, thin film solar cells (TFSC) have gained considerable interest as an economically feasible alternative to conventional silicon (Si) photovoltaic devices. TFSCs have the potential to be as efficient as Si solar cells both in terms of conversion efficiency as well as cost. The advantages of TFSC are that they are easy to prepare, lesser thickness, requires lesser materials, light weight, low cost and opto-electronic properties can be tuned by varying the process parameters. The present study is focused on the fabrication of AgInS2/ZnS heterojunction thin film solar cell. AgInS2 absorber layer is deposited using both vacuum (sputtering/sulfurization) and non-vacuum (ultrasonic spray pyrolysis) techniques. ZnS window layer is prepared using thermal evaporation technique, detailed experimental investigation has been conducted and the results have been reported in this work. The thesis is divided into 6 chapters. Chapter 1 gives general introduction about solar cells and working principle of solar cell. It also discusses thin film solar cell technology and its advantages. Layers of thin film solar cell structure, Significance of each layers and possible materials to be ...

Une cellule qui convertit l'énergie chimique en énergie électrique de manière écologique sur le principe de l'électrochimie et inversée par Sir William Grove en 1839 est connue pour être une « pile à combustible ».Il est devenu une source d'énergie vitale pour le XXIe siècle. Différents types de piles à combustible sont inventés en fonction de leur température de fonctionnement et un type de matériau a été utilisé dans lequel la pile à combustible alcaline est l'une des meilleures.La pile à combustible est un convertisseur d'énergie électrochimique au niveau conceptuel le plus simple, c'est l'hydrogène combiné avec de l'oxygène pour produire de l'eau et de l'électricité.Il ne stocke pas l'énergie elle-même.Il s'agit d'un processus d'écoulement qui aspire le combustible liquide ou gazeux du réservoir séparé et, si nécessaire, le convertit en hydrogène dans le reformeur.L' hydrogène est pris en combinaison avec de l'air oxygéné dans la pile à combustible pour produire de l'eau et de l'électricité.Le processus de conversion d'énergie dans la pile à combustible est donc intrinsèquement propre et silencieux.Généralement, d'autres combustibles tels que le gaz naturel, le méthanol, l'éthanol et même le charbon peuvent également être utilisés.L' objet de cette étude est de résumer les caractéristiques de la pile à combustible alcaline. Una celda que convierte la energía química en energía eléctrica como forma ecológica según el principio de electroquímica e invertida por Sir William Grove en 1839 se conoce como "pila de combustible".Se convirtió en una fuente vital de energía para el siglo XXI. Se inventan diferentes tipos de pilas de combustible en función de su temperatura de trabajo y se ha utilizado un tipo de material en el que la pila de combustible alcalina es una de las mejores. La pila de combustible es un convertidor de energía electroquímica en el nivel conceptual más simple. Se combina hidrógeno con oxígeno para producir agua y electricidad. No almacena la energía en sí misma. Es un proceso de flujo que extrae combustible líquido o gaseoso del tanque separado y, si es necesario, lo convierte en hidrógeno en el reformador. El hidrógeno se toma combinado con aire de oxígeno en la pila de combustible para producir agua y electricidad. El proceso de conversión de energía en la pila de combustible es, por lo tanto, intrínsecamente limpio y silencioso. También se pueden utilizar otros combustibles como el gas natural, el metanol, el etanol e incluso el carbón. El objetivo de este estudio es: resumir las características de la pila de combustible alcalina. A cell which converts the chemical energy into electric energy as eco-friendly way on the principle of electrochemical and Inverted by Sir William Grove in 1839 is known to be "fuel cell".It became a vital source of energy for the 21st Century.Different types of fuel cell are invented based on their working temperature and a type of material has been used in which alkaline fuel cell is one of the best.Fuel cell is an electro-chemical energy converter at the simplest conceptual level it's combined hydrogen with oxygen to produced water and electricity.It does not store the energy itself.It is flow process which draws liquid or gaseous fuel from separated tank and if necessary converse it to hydrogen in reformer.The hydrogen is taken combined with oxygen air in the fuel cell to produced water and electricity.The energy conversion process in the fuel cell is therefore intrinsically clean and silent.Generally other fuel such as natural gas, methanol, ethanol and even coal can also be used.The object of this study is to summarize the characteristic of the alkaline fuel cell. ومن المعروف أن الخلية التي تحول الطاقة الكيميائية إلى طاقة كهربائية كطريقة صديقة للبيئة على مبدأ الكهروكيميائية ومقلوبة من قبل السير ويليام غروف في عام 1839 لتكون "خلية الوقود" أصبحت مصدرًا حيويًا للطاقة في القرن الحادي والعشرين. تم اختراع أنواع مختلفة من خلايا الوقود بناءً على درجة حرارة عملها وتم استخدام نوع من المواد تكون فيها خلية الوقود القلوية واحدة من الأفضل. خلية الوقود عبارة عن محول طاقة كهروكيميائي في أبسط مستوى مفاهيمي، فهو يجمع بين الهيدروجين والأكسجين لإنتاج الماء والكهرباء. لا يخزن الطاقة نفسها. إنها عملية التدفق التي تسحب الوقود السائل أو الغازي من الخزان المنفصل وإذا لزم الأمر تحوّله إلى الهيدروجين في مصلح. يتم أخذ الهيدروجين مع هواء الأكسجين في خلية الوقود لإنتاج الماء والكهرباء. وبالتالي فإن عملية تحويل الطاقة في خلية الوقود نظيفة وصامتة بشكل جوهري. بشكل عام يمكن أيضًا استخدام وقود آخر مثل الغاز الطبيعي والميثانول والإيثانول وحتى الفحم. الهدف من هذه الدراسة هو تلخيص خصائص خلية الوقود القلوية.

This erratum corrects the following typographical errors in the published article without affecting the scientific results and conclusions of the original article. Cet erratum corrige les erreurs typographiques suivantes dans l'article publié sans affecter les résultats scientifiques et les conclusions de l'article original. Esta errata corrige los siguientes errores tipográficos en el artículo publicado sin afectar los resultados científicos y las conclusiones del artículo original. يصحح هذا الخطأ الأخطاء المطبعية التالية في المقال المنشور دون التأثير على النتائج والاستنتاجات العلمية للمقال الأصلي.

This study aimed to experimentally investigate the kinetic compensation effects (KCEs) during Loy Yang brown coal char gasification in an O2 environment at atmospheric pressure in a fluidized-bed g...