89 research outputs found

    Power management and control strategies for off-grid hybrid power systems with renewable energies and storage

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    This document is the Accepted Manuscript of the following article: Belkacem Belabbas, Tayeb Allaoui, Mohamed Tadjine, and Mouloud Denai, 'Power management and control strategies for off-grid hybrid power systems with renewable energies and storage', Energy Systems, September 2017. Under embargo. Embargo end date: 19 September 2018. The final publication is available at Springer via https://doi.org/10.1007/s12667-017-0251-y.This paper presents a simulation study of standalone hybrid Distributed Generation Systems (DGS) with Battery Energy Storage System (BESS). The DGS consists of Photovoltaic (PV) panels as Renewable Power Source (RPS), a Diesel Generator (DG) for power buck-up and a BESS to accommodate the surplus of energy, which may be employed in times of poor PV generation. While off-grid DGS represent an efficient and cost-effective energy supply solution particularly to rural and remote areas, fluctuations in voltage and frequency due to load variations, weather conditions (temperature, irradiation) and transmission line short-circuits are major challenges. The paper suggests a hierarchical Power Management (PM) and controller structure to improve the reliability and efficiency of the hybrid DGS. The first layer of the overall control scheme includes a Fuzzy Logic Controller (FLC) to adjust the voltage and frequency at the Point of Common Coupling (PCC) and a Clamping Bridge Circuit (CBC) which regulates the DC bus voltage. A maximum power point tracking (MPPT) controller based on FLC is designed to extract the optimum power from the PV. The second control layer coordinates among PV, DG and BESS to ensure reliable and efficient power supply to the load. MATLAB Simulink is used to implement the overall model of the off-grid DGS and to test the performance of the proposed control scheme which is evaluated in a series of simulations scenarios. The results demonstrated the good performance of the proposed control scheme and effective coordination between the DGS for all the simulation scenarios considered.Peer reviewedFinal Accepted Versio

    Real-time testing of energy storage systems in renewable energy applications

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    Energy storage systems provide a promising solution for the renewable energy sector to facilitate large-scale grid integration. It is thus very important to explore means to validate their control scheme and their behaviour in the intended application before actual commissioning. This paper presents a reduced-scale hardware-in-the-loop simulation for initial testing of the performance of energy storage systems in renewable energy applications. This relieves the need of selecting and tuning a detailed model of the energy storage element. A low-power test rig emulating the storage element and the power converter is interfaced with a real time digital simulator to allow dynamic experimental tests under realistic conditions. Battery energy storage for smoothing the output power of a variable speed wind turbine is considered in this paper; however the proposed test methodology can be easily adapted for other storage elements in renewable energy, distributed generation and smart grid applications. The proposed HIL simulation is detailed and the experimental performance is shown

    Joint Computing and Electric Systems Optimization for Green Datacenters

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    This chapter presents an optimization framework to manage green datacenters using multilevel energy reduction techniques in a joint approach. A green datacenter exploits renewable energy sources and active Uninterruptible Power Supply (UPS) units to reduce the energy intake from the grid while improving its Quality of Service (QoS). At server level, the state-of-the-art correlation-aware Virtual Machines (VMs) consolidation technique allows to maximize server’s energy efficiency. At system level, heterogeneous Energy Storage Systems (ESS) replace standard UPSs, while a dedicated optimization strategy aims at maximizing the lifetime of the battery banks and to reduce the energy bill, considering the load of the servers. Results demonstrate, under different number of VMs in the system, up to 11.6% energy savings, 10.4% improvement of QoS compared to existing correlation-aware VM allocation schemes for datacenters and up to 96% electricity bill savings

    Optimum community energy storage system for demand load shifting

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    Community energy storage (CES) is becoming an attractive technological option to facilitate the use of distributed renewable energy generation, manage demand loads and decarbonise the residential sector. There is strong interest in understanding the techno-economic benefits of using CES systems, which energy storage technology is more suitable and the optimum CES size. In this study, the performance including equivalent full cycles and round trip efficiency of lead-acid (PbA) and lithium-ion (Li-ion) batteries performing demand load shifting are quantified as a function of the size of the community using simulation-based optimisation. Two different retail tariffs are compared: a time-of-use tariff (Economy 7) and a real-time-pricing tariff including four periods based on the electricity prices on the wholesale market. Additionally, the economic benefits are quantified when projected to two different years: 2020 and a hypothetical zero carbon year. The findings indicate that the optimum PbA capacity was approximately twice the optimum Li-ion capacity in the case of the real-time-pricing tariff and around 1.6 times for Economy 7 for any community size except a single home. The levelised cost followed a negative logarithmic trend while the internal rate of return followed a positive logarithmic trend as a function of the size of the community. PbA technology reduced the levelised cost down to 0.14 £/kW h when projected to the year 2020 for the retail tariff Economy 7. CES systems were sized according to the demand load and this approximated the performance of PbA and Li-ion batteries, the capital cost per unit energy storage (kW h) of the latter assumed to be the double

    GESTION DES FLUX ÉNERGÉTIQUE DANS UN SYSTÈME PHOTOVOLTAÏQUE AVEC STOCKAGE CONNECTER AU RÉSEAU – Application à l'habitat

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    The work done during this thesis contributes to the intensive penetration of the photovoltaic electricity production into the electric grid. Photovoltaic energy holds an immense potential, in particular in the housing sector, but intermittent nature limits its large scale development. In this thesis, we propose to add a storage element to the grid connected photovoltaic system (housing application). First, we introduce the notion of energy management in these systems called « hybrids systems ». The objective is to reduce the peak power consumption and production. Next, we propose and study optimized energy strategies based on predictive indications of irradiation, ambient temperature, power consumption and electricity grid prices. Finally, we bring theoretical solutions to the real time energy management, notably by proposing a solution to the problem of prediction uncertainty.Ces travaux de thèse constituent une contribution à l'introduction massive de la production photovoltaïque (PV) sur le réseau électrique. L'énergie PV possède un potentiel immense, notamment dans le secteur de l'habitat, mais l'effet d'intermittence limite son développement à grande échelle. Dans cette thèse nous proposons d'ajouter un élément de stockage aux systèmes photovoltaïques connectés au réseau dans l'habitat. Nous commençons par introduire la notion de gestion d'énergie dans ces systèmes dits « hybrides », dont l'objectif qui a été fixé est de réduire les pics de puissance appelée, voire produite. Ensuite, nous proposons et étudions des stratégies de gestion optimisées d'énergie basées sur des données prévisionnelles d'irradiations, de températures ambiante, de consommation et des prix de l'énergie. Enfin, nous apportons des solutions théoriques originales de gestion en temps réel, notamment en introduisant des réponses au problème des incertitudes sur les prévisions

    LAZY Todo : gestionnaire de tâches en ligne

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    LAZY Todo est une application web multi-utilisateurs de gestion de tâches destinée aux services informatiques de petite et moyenne taille. Elle est basée sur les travaux de David Allen et ses travaux sur « Getting Things Done » (GTD). L'interface de LAZY Todo est en réalité ce qui la distingue le plus des autres systèmes de gestion de tâches. Mais c'est surtout son ergonomie, son intuitivité et sa capacité à afficher de manière lisible et logique chaque information à l'écran qui font sa force. Ainsi, on peut afficher les tâches par centaines si besoin sans nécessiter l'usage du clic, de la molette ou même des ascenseurs. L'application est composée de 4 modules : un module principal de gestion de tâches, un module permettant de rechercher dans les archives du travail effectué, un module de partage de savoirs (sorte de FAQ), un module d'administration

    Lazy News

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    LazyNews est une application web plein écran permettant de gérer ses annonces dynamiquement sur un parc d’écrans autonomes.Très peu gourmande en ressources, elle peut s’installer sur du matériel informatique en fin de vie. L'application est actuellement déployée dans plusieurs composantes de l’Université de Tours ainsi que dans différents laboratoires CNRS. LazyNews est distribué sous licence CECILL et fait l’objet de développements annexes comme un plugin qui permet d’afficher l’emploi du temps des salles en alternance avec les informations diffusées.L’architecture nécessite un serveur web, et autant d’écrans et de terminaux informatiques que de points de diffusions souhaités.Le déploiement ne nécessite pas d’installation logicielle ni sur les postes de gestion ni sur les points de diffusions.Principales fonctionnalités :- Gestion de plages horaires / groupes d’écrans / catégories- Gestion multi-sites (par étages, bâtiments, laboratoires, composantes, ...)- Programmation des dates de début et de fin d’affichage- Personnalisation aisée d'une ou plusieurs charte graphique (via les CSS) - Prise en charge des écrans de tous types et de toutes tailles - Temporisation des messages en fonction de leur longueur ou de leur importance- Interface de gestion multi-utilisateursTechnologies employées: MySQL, PHP, JAVASCRIPT (AJAX), HTML, CSS

    Stockage et systèmes photovoltaïques connectés au réseau

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    Intelligente dezentrale Energiespeichersysteme

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