Computing an Optimal Control Policy for an Energy Storage

We introduce StoDynProg, a small library created to solve Optimal Control problems arising in the management of Renewable Power Sources, in particular when coupled with an Energy Storage System. The library implements generic Stochastic Dynamic Programming (SDP) numerical methods which can solve a large class of Dynamic Optimization problems. We demonstrate the library capabilities with a prototype problem: smoothing the power of an Ocean Wave Energy Converter. First we use time series analysis to derive a stochastic Markovian model of this system since it is required by Dynamic Programming. Then, we briefly describe the "policy iteration" algorithm we have implemented and the numerical tools being used. We show how the API design of the library is generic enough to address Dynamic Optimization problems outside the field of Energy Management. Finally, we solve the power smoothing problem and compare the optimal control with a simpler heuristic control.Comment: Part of the Proceedings of the 6th European Conference on Python in Science (EuroSciPy 2013), Pierre de Buyl and Nelle Varoquaux editors, (2014

Conception et Mise en Oeuvre d’un Emulateur de Chaînes de Conversion avec Lissage : Applications aux Houlogénérateurs Directs

National audienceL'intégration au réseau de la production des sources d'énergies marines renouvelables est une problématique majeure : lissage de la production, respect de la contrainte de qualité d'énergie, autant de travaux à mener afin d'accroître le taux de pénétration de ces sources dans les réseaux électriques futurs. Ainsi le développement des bancs de test s'avère indispensable pour étudier et contribuer à la validation de tels travaux. Cet article présente la modélisation et la conception d'un dispositif permettant de valider des modèles énergétiques de la chaine électrique d'un houlogénérateur et tester matériellement les lois de gestion du lissage. Le système est composé de deux ponts triphasés dos-à-dos : un pont émulant l'ensemble convertisseur-génératrice avec sa loi de récupération d'énergie et un autre pont injectant l'énergie au réseau, et d'un système de lissage composé essentiellement d'un hacheur réversible et d'un banc de supercondensateurs, piloté selon une loi de gestion donnée

Design of an electro-mechanical portable system using natural human body movements for electricity generation

International audienceIn this article, the authors present the energy potential associated with an electromechanical resonant generator that uses natural movements of the human body during walking motion, as a means of increasing the autonomy of portable electronic systems. The article begins by characterizing the human walk in terms of frequency and hip displacement amplitude. A combined mechanical and electrical study is then conducted in order to determine an order of magnitude for recoverable power

Electromagnetic Resonant Generator

International audienceIn this paper, the authors present the energy production potential of a mechanically-resonant electrical generator system, which makes use of natural human walking movements. The characteristics associated with the human walk will be discussed first, followed by the electromechanical modeling approach employed. The choice of electromechanical architecture will be justified and the permanent magnet and moving coil structure can then be modeled and optimized. A demonstration device has also been generated and tested in order to validate the concept developed as well as the theoretical models derived

Optimization Material Distribution methodology: Some electromagnetic examples

International audienceIn this paper, a new approach towards Optimization Material Distribution (OMD) is proposed. The principle behind this approach is to use a surface genetic algorithm to determine material distribution within a fixed Finite Element Computation mesh. The method proves to be highly adaptive to various kinds of electromagnetic actuator optimization approaches. Several optimal electromagnetic examples are presented

Modélisation des pertes dans les aimants d'un multiplicateur magnétique pour l'éolien

International audienceModélisation des pertes dans les aimants d'un multiplicateur magnétique pour l'éolie

Design and Optimization of Magnetic Gears with Arrangement and Mechanical Constraints for Wind Turbine Applications

International audienceThis article focuses on the design and optimization of magnetic and mechanical (structural) parts of magnetic gears for wind turbine applications. In particular, this design takes into account the structural aspects of magnetic gears as well as the system's mechanical constraints (deformation and stress). Geometric parameters have been optimized in order to minimize the material costs for a 3.9 MW, 15 rpm wind turbine. This optimization strategy includes both magnetostatic and mechanical stationary finite element analyses. Optimization results underscore the necessity to take mechanical constraints into account, especially for the fixed ferromagnetic pole pieces

Eco-design of Electromagnetic Energy Converters: The case of the electrical transformer

International audienceThis paper presents the first results of the ecodesign problematic in case of one of the simplest electromagnetic energy converter: the single-phase electric transformer connected to a constant frequency and voltage power supply. The optimization of its sizes is led with the following objectives: the active mass and the global life cycle energy cost. We first compare optimization's results to those with "classic" mass versus power losses (copper and iron losses) optimization for several times of use ratio. This leads to recognition of the significant impact of the life cycle energy on the arrangement of the optimal Pareto fronts, explained by conflicting energy contribution in the life cycle global energy cost objective. Then we logically observe that the life cycle assessment impact is more significant when the real use duration is smaller than the lifetime. After that, the sensitivity of the optimization's results to the elementary raw materials energy costs is considered with the same times of use ratio. At last, some optimizations are run with a different raw material: aluminium instead of copper for the windings

Caractérisation d'un générateur portable : de l'énergie humaine à l'électricité

National audienceDans cet article, nous nous intéressons à la problématique de l'alimentation des appareils portables liée à la consommation d'accumulateurs et à la dépendance des recharges sur secteur. Le corps humain produit de l'énergie renouvelable, non polluante et de durée de vie élevée : entre chaleur dégagée, lumière reçue et énergie mécanique disponible, cette dernière est déjà exploitée dans diverses applications portables, comme les postes de radio, les lampes ou plus récemment les téléphones portables. Nous proposons dans cet article, une analyse expérimentale d'un générateur intégré dans un poste de radio afin d'en évaluer les avantages et inconvénients puis de proposer des améliorations

Estimation method for evaluating the wave-induced flicker level emitted by a tidal energy farm

International audienceThe inherently fluctuating nature of sea waves can be reflected to a significant extent in the power output of tidal turbines. However, these fluctuations can give rise to power quality issues such as flicker. Hence, it is important to assess the impact which tidal farms may have on their local network before such power plants are allowed to connect to the grid. This paper analyses under which sea-state and grid conditions a 30 MW rated tidal farm breaches the grid code requirements in terms of short-term flicker level. Then, it describes a simplified method for estimating the flicker level by means of an equivalent sinusoidally-modulated voltage profile