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vignette|Cerfs-volants gonflables, sans armature. vignette|Cerf-volant triangulaire. thumb|Cerf-volant en forme d'étoile, à Hockenheim en Allemagne. Un cerf-volant est un aérodyne assez léger pour être mu par les forces aérodynamiques, lancé et manœuvré depuis le sol à l'aide d'un ou plusieurs fils. Sa structure la plus commune se compose d'une pièce de toile ou de papier plus ou moins tendue sur une armature. Étymologie thumb|left|Le Cerf-volant (Francisco de Goya, 1778, musée du Prado) Le mot « cerf-volant » (1669) viendrait de serp-volante, serpe étant un mot féminin en ancien français pour désigner un serpent. Le mot serpe est d'origine méridionale. En occitan, cerf-volant se dit sèrp-volaira ou sèrp-volanta et désigne bien un serpent-volant. Pierre Augustin Boissière de Sauvages (1710-1795) dans son Dictionnaire languedocien-François donne même deux variantes serf ou serpe pour désigner le serpent. Cela reste une hypothèse. En breton (sarpant-nij), en wallon (dragon)

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Le cours présente les bases du comportement des structures, de la détermination des efforts qui y agissent et les principes de leur dimensionnement. Le cours est basé sur la résolution des efforts par la statique graphique.

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Crosswind Kite Control - A Benchmark Problem for Advanced Control and Dynamic Optimization

Dominique Bonvin, Sean Costello, Grégory François

This article presents a kite control and optimization problem intended as a benchmark problem for advanced control and optimization. We provide an entry point to this exciting renewable energy system for researchers in control and optimization methods looking for a realistic test bench, and/or a useful application case for their theory. The benchmark problem in this paper can be studied in simulation, and a complete Simulink model is provided to facilitate this. The simulated scenario, which reproduces many of the challenges presented by a real system, is based on experimental studies from the literature, industrial data and the first author’s own experience in experimental kite control. In par- ticular, an experimentally validated wind turbulence model is included, which subjects the kite to realistic disturbances. The benchmark problem is that of controlling a kite such that the average line tension is maximized. Two different models are provided: A more comprehensive one is used to simulate the ’plant’, while a simpler ’model’ is used to design and implement control and optimization strategies. This way, uncertainty is present in the form of plant-model mismatch. The outputs of the plant are corrupted by measurement noise. The maximum achievable average line tension for the plant is calculated, which should facilitate the performance comparison of different algorithms. A simple control strategy is implemented on the plant and found to be quite suboptimal, even if the free parameters of the algorithm are well tuned. An open question is whether or not more advanced control algorithms could do better.

Wiley-Blackwell2017

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Application of Real-Time Optimization Methods to Energy Systems in the Presence of Uncertainties and Disturbances

Dominique Bonvin, Sean Costello, Grégory François

In practice, the quest for the optimal operation of energy systems is complicated by the presence of operating constraints, which includes the need to produce the power required by the user, and by the need to account for uncertainty. The latter concept incorporates the potential inaccuracies of the models at hand but also degradation effects or unexpected changes, such as, e.g. random load changes or variations of the availability of the energy source for renewable energy systems. Since these changes affect the optimal values of the operating conditions, online adaptation is required to ensure that the system is always operated optimally. This typically implies the online solving of an optimization problem. Unfortunately, the applicability and the performances of most model-based optimization methods rely on the quality of the available model of the system under investigation. On the other hand, Real-time optimization (RTO) methods use the available online measurements in the optimization framework and are, thus, capable of bringing the desired self-optimizing control reaction. In this article, we show the benefits of using several RTO methods (co-) developed by the authors to energy systems through the successful application of (i) "Real-Time Optimization via Modifier Adaptation" to an experimental solid oxide fuel cells (SOFC) stack, of (ii) the recently released "SCFO-solver" (where SCFO stands for “Sufficient Conditions of Feasibility and Optimality”) to an industrial SOFC stack, and of (iii) Dynamic RTO to a simulated tethered kite for renewable power production. It is shown how such problems can be formulated and solved, and significant improvements of the performances of the three aforementioned energy systems are illustrated.

2015

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Analysis of the Maximum Efficiency of Kite-Power Systems

Dominique Bonvin, Sean Costello, Grégory François

This paper analyzes the maximum power that a kite, or system of kites, can extract from the wind. Firstly, a number of existing results on kite system efficiency are reviewed. The results that are generally applicable require significant simplifying assumptions, usually neglecting the effects of inertia and gravity. On the other hand, the more precise analyses are usually only applicable to a particular type of kite-power system. Secondly, a novel result is derived that relates the maximum power output of a kite system to the angle of the average aerodynamic force produced by the system. This result essentially requires no limiting assumptions, and as such it is generally applicable. As it considers average forces that must be balanced, inertial forces are implicitly accounted for. In order to derive practically useful results, the maximum power output is expressed in terms of the system overall strength-to-weight ratio, the tether angle and the tether drag through an efficiency factor. The result is a simple analytic expression that can be used to calculate the maximum power-producing potential for a system of wings, flying either dynamically or statically, supported by a tether. As an example, the analysis is applied to two systems currently under development, namely, pumping-cycle generators and jet-stream wind power.

2015

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Aéronef

vignette|Une montgolfière. Un aéronef est un moyen de transport capable de s'élever et de se mouvoir en altitude, au sein de l'atmosphère terrestre. Les sciences et technologies permettant de constru

Wing

A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoil

Avion

thumb|Le Concorde au jubilé de la reine du Royaume-Uni. thumb|Un North American P-51 Mustang en vol. Photo prise durant un show aérien dans la base de l'Air Force à Langley, en Virginie (États-Unis).