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Tarek Ahmed-Ali

Bio: Tarek Ahmed-Ali is an academic researcher from University of Caen Lower Normandy. The author has contributed to research in topics: Observer (quantum physics) & Nonlinear system. The author has an hindex of 22, co-authored 84 publications receiving 1897 citations. Previous affiliations of Tarek Ahmed-Ali include Centre national de la recherche scientifique.


Papers
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Journal ArticleDOI
TL;DR: The proposed sliding-mode control approach has been validated on a 1.5-MW three-blade wind turbine using the national renewable energy laboratory wind turbine simulator FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code and results show that the proposed control strategy is effective in terms of power regulation.
Abstract: This paper deals with the power generation control in variable-speed wind turbines. These systems have two operation regions which depend on wind turbine tip speed ratio. A high-order sliding-mode control strategy is then proposed to ensure stability in both operation regions and to impose the ideal feedback control solution in spite of model uncertainties. This control strategy presents attractive features such as robustness to parametric uncertainties of the turbine. The proposed sliding-mode control approach has been validated on a 1.5-MW three-blade wind turbine using the national renewable energy laboratory wind turbine simulator FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code. Validation results show that the proposed control strategy is effective in terms of power regulation. Moreover, the sliding-mode approach is arranged so as to produce no chattering in the generated torque that could lead to increased mechanical stress because of strong torque variations.

343 citations

Journal ArticleDOI
TL;DR: In this article, a second-order sliding mode is proposed to control the wind turbine DIF according to references given by an MPPT, which can directly track the DFIG torque leading to maximum power extraction.
Abstract: This paper deals with power extraction maximization of a doubly fed induction generator (DFIG)-based wind turbine. These variable speed systems have several advantages over the traditional wind turbine operating methods, such as the reduction of the mechanical stress and an increase in the energy capture. To fully exploit this latest advantage, many control schemes have been developed for maximum power point tracking (MPPT) control schemes. In this context, this paper proposes a second-order sliding mode to control the wind turbine DFIG according to references given by an MPPT. Traditionally, the desired DFIG torque is tracked using control currents. However, the estimations used to define current references drive some inaccuracies mainly leading to nonoptimal power extraction. Therefore, using robust control, such as the second-order sliding mode, will allow one to directly track the DFIG torque leading to maximum power extraction. Moreover, the proposed control strategy presents attractive features such as chattering-free behavior (no extra mechanical stress), finite reaching time, and robustness with respect to external disturbances (grid) and unmodeled dynamics (generator and turbine). Simulations using the wind turbine simulator FAST and experiments on a 7.5-kW real-time simulator are carried out for the validation of the proposed high-order sliding mode control approach.

269 citations

Journal ArticleDOI
TL;DR: The experimental validation of a Matlab-Simulink simulation tool of marine current turbine (MCT) systems is evaluated within the context of speed control of a permanent magnet synchronous generator-based (PMSG) MCT.
Abstract: This paper deals with the experimental validation of a Matlab-Simulink simulation tool of marine current turbine (MCT) systems. The developed simulator is intended to be used as a sizing and site evaluation tool for MCT installations. For that purpose, the simulator is evaluated within the context of speed control of a permanent magnet synchronous generator-based (PMSG) MCT. To increase the generated power, and therefore the efficiency of an MCT, a nonlinear controller has been proposed. PMSG has been already considered for similar applications, particularly wind turbine systems using mainly PI controllers. However, such kinds of controllers do not adequately handle some of tidal resource characteristics such as turbulence and swell effects. Moreover, PMSG parameter variations should be accounted for. Therefore, a robust nonlinear control strategy, namely second-order sliding mode control, is proposed. The proposed control strategy is inserted in the simulator that accounts for the resource and the marine turbine models. Simulations using tidal current data from Raz de Sein (Brittany, France) and experiments on a 7.5-kW real-time simulator are carried out for the validation of the simulator.

165 citations

Journal ArticleDOI
TL;DR: By using a small gain approach, sufficient conditions are provided, which involve both the delay and the sampling period, ensuring exponential convergence of the observer system error, which is robust with respect to measurement errors and perturbations of the sampling schedule.

116 citations

Journal ArticleDOI
TL;DR: In order to achieve robust output tracking for a class of uncertain triangular systems, a combination of a robust sliding observer and a backstepping procedure is introduced.
Abstract: In order to achieve robust output tracking for a class of uncertain triangular systems, a combination of a robust sliding observer and a backstepping procedure is introduced.

96 citations


Cited by
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Journal Article
TL;DR: In this paper, two major figures in adaptive control provide a wealth of material for researchers, practitioners, and students to enhance their work through the information on many new theoretical developments, and can be used by mathematical control theory specialists to adapt their research to practical needs.
Abstract: This book, written by two major figures in adaptive control, provides a wealth of material for researchers, practitioners, and students. While some researchers in adaptive control may note the absence of a particular topic, the book‘s scope represents a high-gain instrument. It can be used by designers of control systems to enhance their work through the information on many new theoretical developments, and can be used by mathematical control theory specialists to adapt their research to practical needs. The book is strongly recommended to anyone interested in adaptive control.

1,814 citations

Book ChapterDOI
11 Dec 2012

1,704 citations

01 Jan 2016
TL;DR: The stochastic processes and filtering theory is universally compatible with any devices to read and will help you to get the most less latency time to download any of the authors' books like this one.
Abstract: Thank you for reading stochastic processes and filtering theory. Maybe you have knowledge that, people have look numerous times for their favorite novels like this stochastic processes and filtering theory, but end up in harmful downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they are facing with some infectious bugs inside their computer. stochastic processes and filtering theory is available in our digital library an online access to it is set as public so you can download it instantly. Our digital library saves in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Merely said, the stochastic processes and filtering theory is universally compatible with any devices to read.

646 citations

01 Jan 2016
TL;DR: This introduction to infinite dimensional linear systems theory helps people to enjoy a good book with a cup of tea in the afternoon, instead they juggled with some harmful bugs inside their laptop.
Abstract: Thank you very much for downloading introduction to infinite dimensional linear systems theory. As you may know, people have search numerous times for their favorite novels like this introduction to infinite dimensional linear systems theory, but end up in malicious downloads. Rather than enjoying a good book with a cup of tea in the afternoon, instead they juggled with some harmful bugs inside their laptop.

365 citations

Journal ArticleDOI
TL;DR: This article presents basic concepts and recent research directions about the stability of sampled-data systems with aperiodic sampling, and indicates the sources of conservatism, the problems that remain open and the possible directions of improvement.

344 citations