The demand for performance and resources that is placed on the system is dictated by the application alone in non-interactive environments, and by a combination of application and user interactions in interactive environments. Understanding user interaction can provide valuable information about which resources will be needed ahead of time. This leads to performance optimizations such as better resource allocations for applications that can utilize a given resource more productively, and transitioning devices to a more appropriate energy performance state before the demand arrives. The challenge is to provide a performance/energy schedule that best matches the task at hand, since keeping the device in one performance level is not energy efficient due to the continually changing demand placed on the device. This dissertation addresses the challenge of designing energy efficient systems by examining the role of user interaction in energy consumption and in providing an energy-performance schedule that adequately accommodates user demand. It is shown that system performance can be tailored to a user's pattern of interaction and it's energy-performance schedule optimized.First, a detailed design of context capture systems in Linux's X-Window System is presented with an evaluation of the associated storage and computation overheads. Due to the overall low complexity of the application window representations, the overheads of computing interaction identifiers and storing a secondary representation of the application interface within the context capture system are likewise low. Additionally, a Microsoft Windows-based context capture system leveraging the Active Accessibility framework is discussed and applied to improving the navigation of cascading pull-down menus.Secondly, this dissertation addresses the application of interaction capture in energy and delay management of Wireless Network Interface Controllers/Cards (WNICs) and hard drives. The Interaction Aware Prediction (IAP) system for WNICs is evaluated showing that the available power modes can be effectively managed to provide energy efficiency while maintaining performance. Similarly, the Interaction Aware Spin-up Prediction (IASP) uses interaction awareness to reduce or eliminate the interactive delays associated with aggressive hard disk energy management.

South African cement manufacturers are under financial pressure. Sales have declined due to the 2008 recession and electricity costs have tripled from 2005 to 2012. Electricity cost savings are therefore more important than ever. Unfortunately retrofitting highly energyefficient equipment is not ideal. These installations are costly and take a long time to implement. Alternative strategies that can produce quick results in reducing electricity costs are needed. One such alternative is a programme called Demand Market Participation (DMP). The DMP programme was implemented by Eskom, South Africa’s national electricity utility, to reduce electricity demand during supply shortages. This programme offers potential cost savings for clients with excess production capacity. Clients such as cement plants can switch off non-essential production equipment in Eskom’s peak demand periods for a financial incentive. To maximise the benefits for both the clients and Eskom, accurate electricity forecasting is needed, as are systems enabling a quick response to load reduction requests. In this study DMP opportunities on typical cement plants were identified. A DMP strategy to assist cement plants was developed to achieve maximum cost savings without influencing production, quality and safety. An existing energy management system (EnMS) was adapted to incorporate the new DMP participation strategy. The new EnMS and DMP strategy were implemented at a South African cement plant, resulting in savings of R220 000 per month. This translates into an annual cost-saving potential of R2-million for the plant, and an R13- million cost-saving potential for the total South African cement industry. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

The collateral effects of fossil fuels push humanity to seek solutions to these adversities. Energy efficiency and renewable energies have gone from being almost imaginary concepts to necessary. Several studies have shown that self-sufficiency through photovoltaic systems and wind energy is possible. In addition, it is necessary a storage of the surpluses of both since it increases notably the efficiency of these systems and supposes to the short/medium term a saving of money in the consumer. Due to the mentioned before, the aim of the thesis is to convert a science park located in a cold climate such as Sweden into a complex that does not depend energetically on external sources. For this purpose, a series of data from the park were first collected and then simulated and optimised using the HOMER software for different energy configurations. At the same time, a computer code was created in MatLab to enable the energy produced to be used responsibly. The proposed system consists of PV panels, wind turbines and a battery. Thanks to it, a 64 % renewable fraction is achieved, which means a reduction of 27.45 tons of CO2 per year. In addition, through the energy management system created, the electricity contract is reduced, reducing the purchase of electricity during peak hours. It is concluded that the implementation of both proposed systems contributes significantly to the achievement of the sustainable goals set for 2 030 by the main world leaders, even though a total disconnection with the electrical grid has not been achieved.

Envisioned in the next 15 to 30 years in the aviation industry, hybrid-electric propulsion offers theopportunity to integrate new technology bricks providing additional degrees of freedom to improveoverall aircraft performance, limit the use of non-renewable fossil resources and reduce the aircraftenvironmental footprint. Today, hybrid-electric technology has mainly been applied to groundbased transports, cars, buses and trains, but also ships. The feasibility in the air industry has to beestablished and the improvement in aircraft performance has still to be demonstrated. This thesisaims to evaluate the energy savings enabled by electric power in the case of a 70-seat regionalaircraft. First, energy saving opportunities are identified from the analysis of the propulsion andaerodynamic efficiencies of a conventional twin turboprop aircraft. The potential benefits comingfrom the variation of the size of prime movers and the new power managements with the use ofbatteries are studied. Also, possible aerodynamic improvements enabled by new propellerintegrations are considered. For each topic, simplified analyses provide estimated potential ofenergy saving. These results are then used to select four electrified propulsion systems that arestudied in more detail in the thesis: a parallel-hybrid, a turboelectric with distributed propulsion, apartial-turboelectric with high-lift propellers and an all-electric. Evaluating the selected hybrid-electric aircraft is even more challenging that the sizing of the different components, the energymanagement strategies and the mission profiles one can imagine are many and varied. Inaddition, the overall aircraft design process and the evaluation tools need to be adaptedaccordingly. The Airbus in-house Multidisciplinary Design Optimisation platform named XMDO,which includes most of the required modifications, is eventually selected and further developedduring the thesis. For examples, new parametric component models (blown wing, electrical motor,gas turbine, propeller, etc…) are created, a generic formulation for solving the propulsion systemequilibrium is implemented, and simulation models for take-off and landing are improved. In orderto evaluate the energy efficiency of the hybrid-electric aircraft, a reference aircraft equipped with aconventional propulsion system is first optimised with XMDO. Different optimisation algorithms aretested, and the consistency of the new design method is checked. Then, all the hybrid-electricconfigurations are optimised under the same aircraft design requirements as the reference. Forthe electrical components, two levels of technology are defined regarding the service entry date ofthe aircraft. The optimisation results for the turboelectric and the partial-turboelectric are used tobetter understand the potential aerodynamic improvements identified in the first part of the thesis.Optimisations for the parallel-hybrid, including different battery recharge scenarios, highlight thebest energy management strategies when batteries are used as secondary energy sources. All theresults are finally compared to the reference in terms of fuel and energy efficiencies, for the twoelectrical technology levels. The last part of the thesis focuses on the all-electric aircraft, and aimsat identifying the minimum specific energy required for batteries as a function of the aircraft designrange. A trade study is also carried-out in accordance with the service entry date for the otherelectrical components

Le secteur industriel de l'énergie, et les réseaux électriques en particulier, rendent à nos sociétés modernes d'immenses services dont nous ne pouvons plus nous passer. Ils présentent aussi, hélas, un certain nombre de graves inconvénients, notamment en matière d'impact environnemental. Ces inconvénients apparaissent aujourd'hui comme inacceptables; le secteur de l'énergie s'efforce donc actuellement de les amoindrir autant que possible, dans le cadre de ce qu'on appelle la transition énergétique.Outre d'indispensables efforts en matière de sobriété et d'efficacité énergétique, deux grands axes d'amélioration se dessinent: d'une part, le remplacement progressif de certains moyens de production d'électricité conventionnels par des moyens de production renouvelables; et d'autre part, le transfert de certains usages aujourd'hui non-électriques vers l'électricité --- en particulier en matière de mobilité.L'intégration au réseau électrique de ces nouveaux types de dispositifs pose cependant des difficultés techniques considérables, qui motivent depuis le début des années 2000 de nombreux travaux sur le thème de ce que l'on appelle aujourd'hui les "smart grids": des réseaux électriques compatibles avec les exigences de la transition énergétique, c'est-à-dire capables d'accueillir massivement les nouveaux types d'usages comme la production photovoltaïque et les bornes de recharge des véhicules électriques, ceci notamment grâce à l'utilisation accrue des nouvelles technologies de l'information et de la communication. Parmi les difficultés susmentionnées, qui limitent la capacité d'accueil du réseau, figurent les congestions, c'est-à-dire les limites physiques à la puissance que l'on peut faire transiter d'un point à un autre sur une infrastructure donnée. C'est à la gestion des congestions que nos travaux sont consacrés. À ce sujet, la question fondamentale est de déterminer par quel enchaînement de mesures, de calcul, de communications et in fine d'actions, on peut passer d'une situation de contrainte sur un réseau de distribution d'électricité, à une situation où cette contrainte a été éliminée par l'action des flexibilités environnantes; autrement dit, en augmentant ou en réduisant judicieusement la production et/ou la consommation locales, et éventuellement en jouant sur d'autres types de leviers.L'objet de cette thèse est de participer à l'élaboration des outils conceptuels et informatiques qui nous permettront de répondre à la question fondamentale ci-dessus. Nos travaux portent ainsi sur la question de la modélisation des réseaux de distribution d'électricité "flexibles", et sur l'implémentation concrète des modèles retenus sous forme d'un logiciel de simulation ad hoc, parfaitement adapté à l'étude de ce type de réseaux. / The energy sector and the electrical networks in particular, provide great and indispensable services to our modern societies. Unfortunately, they also bring some serious drawbacks, especially with regard to the environment. These drawbacks are becoming more and more unacceptable; that is why the energy sector is trying to reduce them as much as possible, in the framework of the so-called energy transition.In addition to mandatory efforts in terms of energy efficiency and sobriety, two major directions of improvement have been identified: on the one hand, the progressive replacement of some conventional power plants with renewable production units; and on the other hand, the transfer of several non-electrical usages towards electricity --- in particular in the area of mobility.The integration of these new devices into electrical networks raise new technical challenges which, since the early 2000s, have been driving a lot of work about so-called "smart grids": electrical networks compatible with the requirements of the energy transition, ie. able to host new devices like photovoltaic solar panels and charging stations for electric vehicles, notably through the increasing usage of new information and communications technologies.Among the difficulties mentioned above, which limit the hosting capacity of the network, there are congestions ie. physical constraints limiting the amount of power that may be transmitted through a given infrastructure. Our work is devoted to the management of congestions. The fundamental issue thereon is to define a sequence of decisions, computations, communications and in fine actionsthat allows to move from a constrained situation on the electrical distribution network, to a situation in which the action of local flexibilities has lifted the constraint; in other words, to a situation where increasing or decreasing local generation and/or consumption, or taking some other control action, relieved the network.The aim of this thesis is to contribute to the development of conceptual and computing tools that will allow us to answer the fundamental aforementioned issue. Our work thus deals with the modelling of flexible electrical distribution networks, and with the tangible implementation of selected models in the form of ad hoc simulation software, specifically designed for the study of such networks.

Ce travail contribue à l’optimisation d’un système de stockage hybride couplant une batterie lithium-ion et des supercondensateurs pour les véhicules électriques. La complémentarité entre ces deux sources d’énergie permet l’amélioration des performances globales du système. Notre étude porte sur la mise en oeuvre de techniques avancées de contrôle et de gestion de l’énergie. Notre objectif est d’avoir une meilleure utilisation du système de stockage. Dans ce cadre, notre démarche est de développer une gestion d’énergie en temps réel qui tient compte des contraintes électriques et thermiques des systèmes de stockage. Une étude comparative sur les avantages et les inconvénients de différentes techniques de gestion d’énergie nous a permis d’effectuer le choix entre un partage de puissance à moindre coût et un partage performant de l’énergie entre les systèmes de stockage. Un banc expérimental a été mis en oeuvre afin de concrétiser la démarche théorique / This work contributes to the optimization of a hybrid storage system that combines lithium-ion batteries with supercapacitors used for electric vehicles. This hybridization structure was chosen due to the complementarity between both used storage devices. Our study focuses on the implementation of advanced energy control and management techniques. Using better the storage system represents the goal of this thesis. Our approach is to develop a real time algorithm of energy management taking into account battery electrical and thermal behaviors. A comparative study evaluates the benefits and the drawbacks of each proposed strategy in order to offer various choices between low cost power sharing solutions and control strategy with high performances. An experimental bench was implemented to apply the theoretical concept

Cette thèse porte sur les problèmes de stabilité en fréquence et en tension des microréseaux isolés avec forte pénétration d'énergies renouvelables en utilisant des dispositifs de stockage d'énergie, et se divise en deux parties principales.Dans la première partie, nous proposons une conception systématique d'une structure de commande robuste multi-variable pour le réglage de fréquence dans un système de génération de puissance hybride diesel-photovoltaïque-supercondensateur fonctionnant en mode autonome. La structure de commande proposée repose sur une architecture à deux niveaux: les contrôleurs d'asservissement de courant basés sur commande PI classique sont placés sur le niveau de commande inférieur et reçoivent des références d'un niveau supérieur qui, lui, est basé sur commande H-infini. Une méthodologie compréhensive qui traduit les demandes d'ingénierie spécifiques de l'opération du microréseau dans le formalisme de commande H-infini est détaillée. Nous montrons également comment les spécifications de performance dynamiques en boucle fermée doivent à leur tour être prises en compte dans la configuration et le dimensionnement initiaux du microréseau, c'est-à-dire en choisissant de manière appropriée et en évaluant le système de stockage d'énergie. Ensuite, une analyse de performance robuste du contrôleur H-infini synthétisé en présence de diverses perturbations de charge, des variations de puissance active de la source photovoltaïque, et des incertitudes du modèle est effectuée afin de déterminer la plage de variation maximale des paramètres pour laquelle les performances de commande imposées sont respectées pour le point de fonctionnement considéré. Les simulations numériques réalisées avec MATLAB/Simulink montrent l'efficacité de la stratégie de commande robuste de fréquence proposée sur un microréseau d'ordre de quelques MVA. Un banc de test de prototypage rapide, qui est composé d'un système de stockage d'énergie réel à base de supercondensateurs et un réseau diesel-photovoltaïque-charge émulé, est développé afin de valider expérimentalement cette stratégie de commande.La deuxième partie de cette thèse se concentre sur le calcul d'un contrôleur de tension multi-variable basé sur commande H-infini afin de forcer robustement l'amplitude de tension du point de couplage commun à satisfaire des spécifications dynamiques. La même idée de la structure de commande à deux niveaux en cascade - où ce contrôleur est placé sur un niveau de commande supérieur et fournit les références de courant aux contrôleurs de courant placés sur un niveau inférieur - est également adoptée. Ensuite, la performance et la robustesse du contrôleur H-infini proposé en présence de diverses perturbations de puissance réactive de la charge et de la source photovoltaïque, ainsi que des incertitudes du modèle, sont étudiées en utilisant des simulations temporelles MATLAB/Simulink. / This thesis addresses the frequency and voltage stability issues of stand-alone microgrids with high penetration of renewable energy by making use of energy storage devices, and is divided into two main parts.In the first part, we propose a systematic design of a multi-variable robust control structure for frequency regulation in a diesel-photovoltaic-supercapacitor hybrid power generation system operating in stand-alone mode. The proposed control structure relies on a two-level architecture: classical PI-based current tracking controllers are placed on the low control level and receive references from an H-infinity-control-based upper level. A comprehensive methodology that casts the specific engineering demands of microgrid operation into H-infinity control formalism is detailed. It is also shown how closed-loop dynamic performance requirements must at their turn be taken into account in the initial microgrid setup and sizing, namely in appropriately choosing and rating the energy storage system. Then, a robust performance analysis of the synthesized H-infinity controller in the presence of various load disturbances, photovoltaic output active power variations, and model uncertainties is carried out in order to determine the maximum parameter variation range for which the imposed control performances are respected for the considered operating point. Numerical simulations performed with MATLAB/Simulink show the effectiveness of the proposed frequency robust control strategy on a MVA-rated microgrid. A rapid-prototyping test bench, which is composed of a real supercapacitor-based energy storage system and an emulated diesel-photovoltaic-load grid, is developed in order to experimentally validate this control strategy.The second part of this thesis focuses on computing an H-infinity-based multi-variable voltage controller in order to robustly force the voltage magnitude of the point of common coupling to satisfy dynamic specifications. The same idea of cascaded two-level control structure - where this controller is placed on an upper control level and provides the references to current controllers placed on a lower level - is aslo adopted. Then, the performance and robustness of the proposed H-infinity controller in the presence of various load and photovoltaic reactive power disturbances, as well as model uncertainties, are studied based on MATLAB/Simulink time-domain simulations.

As condições de vida na terra estão sendo alteradas de forma ainda desconhecida pelo homem. A eficiência energética é apontada como uma das estratégias de mitigação das mudanças climáticas e melhoria da qualidade de vida. De todos os setores de atividade, a indústria é o maior usuário de energia. Assim, este trabalho focaliza a eficiência energética industrial; trata da questão energia e sustentabilidade, e dos respectivos custos; da evolução dos programas de racionalização de energia e do seu marco regulatório no Brasil, dentre outras forças de mercado, como as resultantes da estrutura competitiva, etc. Finalmente, o trabalho define a gestão da energia com seus instrumentos de controle e, baseado na concepção universal de governança e na governança corporativa, propõe um modelo de governança de energia para a indústria sob requisitos de sustentabilidade. / Life conditions on Earth are being changed by ways still unknown to man. Energy efficiency is one of the strategies to mitigate climate change and to improve quality of life. As manufacturing is the greatest energy user, this work studies industrial energy efficiency, examines the energy and sustainability issue, its costs, the evolution of the regulatory framework, the development of energy rationalizing programs and other relevant market forces in Brazil, as those resulting from the competitive dynamic etc. Finally, the work defines energy management, its control instruments and, based on corporate governance concepts, proposes an energy governance model for manufacturing under sustainability requirements.

O crescente valor pago pela fatura de energia elétrica sucedendo um período de indisponibilidade quando do racionamento em 2001, concomitantemente com as novas regulamentações do setor elétrico, fizeram com que algumas indústrias buscassem melhor entender o negócio energia elétrica de forma a se precaver de um possível novo racionamento. As indústrias foram em busca de preços mais atrativos, objetivando garantir seu processo produtivo com competitividade. O setor elétrico buscou estimular o investimento privado e o crescimento sustentável do mercado de energia elétrica no Brasil, e também incentivar o usuário final a melhor fazer a gestão dos gastos e consumos de energia elétrica através de novas regulamentações, incentivos à eficiência energética, acelerando a competitividade nos preços de energia elétrica, entre outras ações. Este trabalho apresenta um resumo dos fatos relevantes que ocorreram no setor elétrico brasileiro e cita os principais impactos ocorridos na indústria, a transformação do consumidor em cliente, ou seja, de mero pagador de fatura ao responsável pela escolha do fornecedor e o atual gestor do gasto e do consumo de energia em sua indústria. Esta dissertação propõe um modelo de gestão de energia elétrica baseado em um caso de sucesso ocorrido numa grande indústria de alimentos do Brasil, apresentando os resultados obtidos. / The increasing amount paid for the electricity energy invoice after the period of unavailability on the occasion of the energy rationing in 2001, concurrently with the new regulations of the energy sector, have made some industries pursue a better understanding of the energy business in order to avoid a possible new energy rationing. The companies have also been searching for more attractive prices, aiming at ensuring competitiveness in their production process. The electrical energy sector has sought to stimulate private investment and sustainable growth of the energy market in Brazil, apart from providing incentive for the end user in terms of improving their expenditures and energy consumption management through new regulations and incentives for energy efficiency, accelerating the competitiveness of energy price, among other actions. The contents of this dissertation present a summary of relevant facts that occurred in the Brazilian electricity sector. Moreover, they cite the major impacts on the industry, the transformation of consumers into customers, i.e. from a mere bill payer to a customer who is responsible for choosing the energy provider, also becoming the current expenditure and energy consumption manager of their own company. This dissertation proposes a model of energy management based on a successful case occurred in a major food processing industry in Brazil, presenting the results.

In the last two decades, energy is becoming one of the main issues in the manufacturing industry as it contributes substantially to production cost, CO2 emissions, and other destructive environmental impact. Due to rising energy costs, environmental concerns and stringent regulations, manufacturing is increasingly driven towards sustainable manufacturing which needs to address the associated environmental, social and economic aspects simultaneously. One common approach is to achieve sustainability and to implement energy-resource efficient production management systems that enable optimisation of energy consumption and resource utilisation in the production system. However, by reducing energy consumption, the product quality and production cost may be compromised. To remain competitive in the dynamic environment, the energy-efficient management system should not only concern energy consumption but also maintain product quality and production efficiency. This thesis presents a development of the Energy-smart Production Management (e-ProMan) system which provides a systematic, virtual simulation that integrates manufacturing data relating to thermal effect and correlation analysis between energy flow, work flow and data flow for the heating, ventilation and air conditioning (HVAC) system and production process. First, the e-ProMan system comprises of the multidimensional analysis between energy flow, work flow and data flow. The results showed that the product quality is significantly affected by ambient temperature in CNC precision machining. Product quality appears to be improved at lower temperatures. This research highlights the significance of ambient temperature in sustainable precision machining. Second, the simulation experiment was modelled at the production process due to it being the main source of energy consumption in manufacturing. An up-hill workload scenario was found to be the most energy and cost-efficient production processes. In other words, energy consumption, CO2 emission and total manufacturing cost could be reduced when workload capacity and operating machine increase incrementally. Moreover, the e-ProMan system was modelled and simulated using the weather forecast and real-time ambient temperature to reduce energy consumption of the HVAC system. The e-ProMan system results in less energy consumption compared to the fuzzy control system. To conclude, the e-ProMan demonstrates energy efficiency at all relevant levels in the manufacturing: machine, process and plant. For the future research, the e-ProMan system needs to be applied and validated in actual manufacturing environments.