Dissertations / Theses: 'Offshore renewable energy systems'

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Burchell, Joseph William. "Advancement of direct drive generator systems for offshore renewable energy production." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33263.

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As machine topologies and technologies mature, the fundamental function of the device is honed. Direct drive machines have the potential to launch the renewable energy sector into a new era of large scale, reliable, offshore power generation. With advancements in new technologies, such as superconductivity, the reduction of generator mass due to incorporation of machine and device structures, the continued advancements in component and system reliability; direct drive generators have the ability to outsize geared wind systems and simplify submerged linear and rotary power generation. The research held within this thesis will focus on improving direct drive power take off systems for offshore renewable energy power generation by splitting the area into four parts. The first part will discuss the various methods of energy extraction within the offshore and marine environment. The future of the sector will be discussed, and a forecast of technological advancement and existing reliability issues will be provided based on current data. The second part will focus on drive trains and direct drive generators, assessing the current topologies and suggesting alternatives that may thrive in a variety of large and small offshore renewable machines. The third part investigates the application of novel linear bearings in direct drive systems for offshore and submerged operation. A brief study of the loads found in wave applications will be presented and the testing of several polymer bearing materials will be outlined. The final part will discuss the potential benefits of flooding the airgap of a direct drive generator with sea water for marine applications. Results will be presented from two linear test rigs and the marinisation of devices will conclude the report.

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Beyene, Mussie Abraham. "Modelling the Resilience of Offshore Renewable Energy System Using Non-constant Failure Rates." Thesis, Uppsala universitet, Institutionen för elektroteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-445650.

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Offshore renewable energy systems, such as Wave Energy Converters or an Offshore Wind Turbine, must be designed to withstand extremes of the weather environment. For this, it is crucial both to have a good understanding of the wave and wind climate at the intended offshore site, and of the system reaction and possible failures to different weather scenarios. Based on these considerations, the first objective of this thesis was to model and identify the extreme wind speed and significant wave height at an offshore site, based on measured wave and wind data. The extreme wind speeds and wave heights were characterized as return values after 10, 25, 50, and 100 years, using the Generalized Extreme Value method. Based on a literature review, fragility curves for wave and wind energy systems were identified as function of significant wave height and wind speed. For a wave energy system, a varying failure rate as function of the wave height was obtained from the fragility curves, and used to model the resilience of a wave energy farm as a function of the wave climate. The cases of non-constant and constant failure rates were compared, and it was found that the non-constant failure rate had a high impact on the wave energy farm's resilience. When a non-constant failure rate as a function of wave height was applied to the energy wave farm, the number of Wave Energy Converters available in the farm and the absorbed energy from the farm are nearly zero. The cases for non-constant and an averaged constant failure of the instantaneous non-constant failure rate as a function of wave height were also compared, and it was discovered that investigating the resilience of the wave energy farm using the averaged constant failure rate of the non-constant failure rate results in better resilience. So, based on the findings of this thesis, it is recommended that identifying and characterizing offshore extreme weather climates, having a high repair rate, and having a high threshold limit repair vessel to withstand the harsh offshore weather environment.

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Heidari, Shayan. "Economic Modelling of Floating Offshore Wind Power : Calculation of Levelized Cost of Energy." Thesis, Mälardalens högskola, Industriell ekonomi och organisation, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-36130.

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Floating offshore wind power is a relatively new technology that enables wind turbines to float above the sea level, tied by anchors at the seabed. The purpose of this work is to develop an economic model for the technology in order to calculate the total cost of a planned wind farm. Cost data are retrieved from reports and academic journals available online. Based on these data, a model in Microsoft Excel is developed which calculates the Levelized cost of energy (LCOE) for floating wind power plants as a function of several input values. As an addition to this model, financing offshore projects are described using literature study and by doing interviews with three major companies, currently investing in offshore wind. As a result, the model allows the user to calculate Capital expenditures, Operating expenditures and LCOE for projects at any given size and at any given site. The current LCOE for a large floating offshore wind farm is indicated to be in the range of 138-147 £/MWh. The outline from interviews was that today there is no shortage of capital for funding wind projects. However, in order to attract capital, the governmental regulatory of that market has to be suitable since it has a crucial impact on price risks of a project.

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Fischer, Felix Friedrich. "The regulation of Section 17 (2a) of the German Energy Economy Act against the background of current developments of the German and European offshore wind industry." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/5750.

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Thesis (MBA (Business Management))--Stellenbosch University, 2008.
ENGLISH ABSTRACT: With the introduction of Section 17 of the EnWG (German Energy Economy Act), the legislator created a new situation for the complex relationships in the German offshore wind industry. The transmission system operators are now obliged not only to provide the connection for offshore wind farms, but also to reimburse the developers of such plants for the costs they incurred in the course of planning the cable connection between the wind farm and the onshore grid. Forecasts had predicted that by 2007 numerous offshore wind farms would be operational. But no development company in the entire sector had moved beyond the planning phase. However, the rapid development of the offshore wind industry is important in order to achieve the German goal to generate 20% of all energy from renewable energy sources by 2020 and thus contribute to the prevention of grave climate changes. It is also important for the domestic labour market and the initiation of further exports of energy technologies. Early domestic growth will eventually payoff as offshore wind energy is implemented by more countries, which will then rely on the experience of German companies. Under these circumstances, Section 17 (2a) S.3 of the EnWG induces a positive impulse for offshore development. Under the financial constraints that dampened the expectations of developers of offshore wind farms, the suggested reimbursement will offer welcome relief. However a broad interpretation of Section 17 (2a) S.3 of the EnWG must be applied in order to reach the goal of actually enhancing offshore development, as is the legislator's intent. Such a broad interpretation of the reimbursement claim will lead to rapid implementation of the new law, as this will be in the interest of the developers and transmission system operators. The developers will have a large interest in beginning with the actual construction of the wind farm, and the transmission system operators will need to proceed with the planning of the cable connection. Even though improvements remain necessary the introduction of Section 17 (2a) S.3 EnWG can be considered a success.
AFRIKAANSE OPSOMMING: Met die inwerkingstelling van afdeling 17 van die EnGW (Duitse Energie Ekonomie Wet), het die regering 'n nuwe situasie geskep vir die komplekse verhouding in die Duitse see-gebonde wind-energie industrie. Die transmissie stelsel operateurs word nou verplig om nie net die verbinding met die wind-plaas te verskaf nie, maar moet ook die ontwikkelaar van die aanleg vergoed vir enige kostes wat hulle aangegaan het met die beplanning van die verbinding tussen die windplaas en die elektrisiteits-netwerk. Vooruitskattings het voorspel dat verskeie see-gebonde windplase operasioneel sou wees teen 2007. Geen ontwikkelingsmaatskappy het egter al tot dusver verder as die beplanningstadium gevorder nie. Desnieteenstaande, die spoedige ontwikkeling van die see-gebonde wind industrie is onontbeerlik in die Duitse mikpunt om 20% van energiebehoeftes op te wek vanuit hernubare bronne teen 2020 en om dus klimaatsverandering teen te werk. Dit is ook belangrik vir werkskepping in Duitsland en vir die uitvoer van energie tegnologie. Spoedige groei in die industrie sal uiteindelik dividende lewer soos seegebonde wind-energie deur ander lande ontwikkel word en gevolglik op Duitse ervaring moet staatmaak. Onder hierdie omstandighede het afdeling 17 (2a) 5.3 van die EnGW 'n positiewe effek op seegebonde ontwikkeling. As gevolg van die dempende effek wat finansiele beperkinge het op die verwagtinge van ontwikkelaars sal die terugbetalings welkome verligting bied. Dit is egter nodig om 'n bree interpretasie van afdeling 17 (2a) 5.3 van die EnGW te gebruik om die mikpunt van werklike bevordering van seegebonde ontwikkeling te bewerkstellig soos die wetgewer beoog. So 'n bree interpretasie sal lei tot spoedige implimentasie van die nuwe wet omdat dit in die belang van ontwikkelaars en transmissie-netwerk eienaars sal wees. Die ontwikkelaars sal baat daarby om spoedig met ontwikkeling te begin, terwyl die netwerk operateurs vordering sal moet maak met die beplanning van die kabel-verbinding. Ten spyte daarvan dat verdere verbeteringe nodig is kan die inwerkingstelling van afdeling 17 (2a) 5.3 van die EnGW as 'n sukses gereken word.

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Lindroth, [formerly Tyrberg] Simon. "Buoy and Generator Interaction with Ocean Waves : Studies of a Wave Energy Conversion System." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-160085.

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On March 13th, 2006, the Division of Electricity at Uppsala University deployed its first wave energy converter, L1, in the ocean southwest of Lysekil. L1 consisted of a buoy at the surface, connected through a line to a linear generator on the seabed. Since the deployment, continuous investigations of how L1 works in the waves have been conducted, and several additional wave energy converters have been deployed. This thesis is based on ten publications, which focus on different aspects of the interaction between wave, buoy, and generator. In order to evaluate different measurement systems, the motion of the buoy was measured optically and using accelerometers, and compared to measurements of the motion of the movable part of the generator - the translator. These measurements were found to correlate well. Simulations of buoy and translator motion were found to match the measured values. The variation of performance of L1 with changing water levels, wave heights, and spectral shapes was also investigated. Performance is here defined as the ratio of absorbed power to incoming power. It was found that the performance decreases for large wave heights. This is in accordance with the theoretical predictions, since the area for which the stator and the translator overlap decreases for large translator motions. Shifting water levels were predicted to have the same effect, but this could not be seen as clearly. The width of the wave energy spectrum has been proposed by some as a factor that also affects the performance of a wave energy converter, for a set wave height and period. Therefore the relation between performance and several different parameters for spectral width was investigated. It was found that some of the parameters were in fact correlated to performance, but that the correlation was not very strong. As a background on ocean measurements in wave energy, a thorough literature review was conducted. It turns out that the Lysekil project is one of quite few projects that have published descriptions of on-site wave energy measurements.

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Paniah, Crédo. "Approche multi-agents pour la gestion des fermes éoliennes offshore." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112067/document.

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La raréfaction des sources de production conventionnelles et leurs émissions nocives ont favorisé l’essor notable de la production renouvelable, plus durable et mieux répartie géographiquement. Toutefois, son intégration au système électrique est problématique. En effet, la production renouvelable est peu prédictible et issue de sources majoritairement incontrôlables, ce qui compromet la stabilité du réseau, la viabilité économique des producteurs et rend nécessaire la définition de solutions adaptées pour leur participation au marché de l’électricité. Dans ce contexte, le projet scientifique Winpower propose de relier par un réseau à courant continu les ressources de plusieurs acteurs possédant respectivement des fermes éoliennes offshore (acteurs EnR) et des centrales de stockage de masse (acteurs CSM). Cette configuration impose aux acteurs d’assurer conjointement la gestion du réseau électrique.Nous supposons que les acteurs participent au marché comme une entité unique : cette hypothèse permet aux acteurs EnR de tirer profit de la flexibilité des ressources contrôlables pour minimiser le risque de pénalités sur le marché de l’électricité, aux acteurs CSM de valoriser leurs ressources auprès des acteurs EnR et/ou auprès du marché et à la coalition de faciliter la gestion des déséquilibres sur le réseau électrique, en agrégeant les ressources disponibles. Dans ce cadre, notre travail s’attaque à la problématique de la participation au marché EPEX SPOT Day-Ahead de la coalition comme une centrale électrique virtuelle ou CVPP (Cooperative Virtual Power Plant). Nous proposons une architecture de pilotage multi-acteurs basée sur les systèmes multi-agents (SMA) : elle permet d’allier les objectifs et contraintes locaux des acteurs et les objectifs globaux de la coalition.Nous formalisons alors l’agrégation et la planification de l’utilisation des ressources comme un processus décisionnel de Markov (MDP), un modèle formel adapté à la décision séquentielle en environnement incertain, pour déterminer la séquence d’actions sur les ressources contrôlables qui maximise l’espérance des revenus effectifs de la coalition. Toutefois, au moment de la planification des ressources de la coalition, l’état de la production renouvelable n’est pas connue et le MDP n’est pas résoluble en l’état : on parle de MDP partiellement observable (POMDP). Nous décomposons le POMDP en un MDP classique et un état d’information (la distribution de probabilités des erreurs de prévision de la production renouvelable) ; en extrayant cet état d’information de l’expression du POMDP, nous obtenons un MDP à état d’information (IS-MDP), pour la résolution duquel nous proposons une adaptation d’un algorithme de résolution classique des MDP, le Backwards Induction.Nous décrivons alors un cadre de simulation commun pour comparer dans les mêmes conditions nos propositions et quelques autres stratégies de participation au marché dont l’état de l’art dans la gestion des ressources renouvelables et contrôlables. Les résultats obtenus confortent l’hypothèse de la minimisation du risque associé à la production renouvelable, grâce à l’agrégation des ressources et confirment l’intérêt de la coopération des acteurs EnR et CSM dans leur participation au marché de l’électricité. Enfin, l’architecture proposée offre la possibilité de distribuer le processus de décision optimale entre les différents acteurs de la coalition : nous proposons quelques pistes de solution dans cette direction
Renewable Energy Sources (RES) has grown remarkably in last few decades. Compared to conventional energy sources, renewable generation is more available, sustainable and environment-friendly - for example, there is no greenhouse gases emission during the energy generation. However, while electrical network stability requires production and consumption equality and the electricity market constrains producers to contract future production a priori and respect their furniture commitments or pay substantial penalties, RES are mainly uncontrollable and their behavior is difficult to forecast accurately. De facto, they jeopardize the stability of the physical network and renewable producers competitiveness in the market. The Winpower project aims to design realistic, robust and stable control strategies for offshore networks connecting to the main electricity system renewable sources and controllable storage devices owned by different autonomous actors. Each actor must embed its own local physical device control strategy but a global network management mechanism, jointly decided between connected actors, should be designed as well.We assume a market participation of the actors as an unique entity (the coalition of actors connected by the Winpower network) allowing the coalition to facilitate the network management through resources aggregation, renewable producers to take advantage of controllable sources flexibility to handle market penalties risks, as well as storage devices owners to leverage their resources on the market and/or with the management of renewable imbalances. This work tackles the market participation of the coalition as a Cooperative Virtual Power Plant. For this purpose, we describe a multi-agent architecture trough the definition of intelligent agents managing and operating actors resources and the description of these agents interactions; it allows the alliance of local constraints and objectives and the global network management objective.We formalize the aggregation and planning of resources utilization as a Markov Decision Process (MDP), a formal model suited for sequential decision making in uncertain environments. Its aim is to define the sequence of actions which maximize expected actual incomes of the market participation, while decisions over controllable resources have uncertain outcomes. However, market participation decision is prior to the actual operation when renewable generation still is uncertain. Thus, the Markov Decision Process is intractable as its state in each decision time-slot is not fully observable. To solve such a Partially Observable MDP (POMDP), we decompose it into a classical MDP and an information state (a probability distribution over renewable generation errors). The Information State MDP (IS-MDP) obtained is solved with an adaptation of the Backwards Induction, a classical MDP resolution algorithm.Then, we describe a common simulation framework to compare our proposed methodology to some other strategies, including the state of the art in renewable generation market participation. Simulations results validate the resources aggregation strategy and confirm that cooperation is beneficial to renewable producers and storage devices owners when they participate in electricity market. The proposed architecture is designed to allow the distribution of the decision making between the coalition’s actors, through the implementation of a suitable coordination mechanism. We propose some distribution methodologies, to this end

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Honnanayakanahalli, Ramakrishna Prajwal. "MODELING, SIMULATION AND OPTIMIZATION OF A SUBMERGED RENEWABLE STORAGE SYSTEM INTEGRATED TO A FLOATING WIND FARM : A feasibility case study on the Swedish side of the Baltic sea, based on the geographical and wind conditions." Thesis, Mälardalens högskola, Framtidens energi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-42321.

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Mathematical modeling and simulations of a submerged renewable storage system integrated to a wind farm, chosen based on the geographical and wind conditions at the Baltic Sea, gives insight on the feasibility of the submerged renewable storage and an approximation of the payback period and profits that could be generated. Genetic Algorithms were used to obtain the optimal number of spheres for a certain depth, based on 2 objective functions I.e. Minimum Life Cycle Cost (LCC) and maximum reduction in wind curtailment. The new arrangement concept shows that the Initial Capital Cost (ICC) could be decreased by 25% to 60% depending upon the number of sphere employed. Based on the inputs considered in the study, the results prove that the submerged renewable storage system would be feasible, and the profits ranging from 15 Million Euro to 29 Million Euro can be achieved at the chosen location, towards the Swedish side of the Baltic sea. Although, in a real life scenario it is assumed that only up to half of the profits obtained in the results would be achievable. The results also show that, the Pump/Turbine with a high turbine efficiency and lower pump efficiency, generated better profits, compared to a Pump/Turbine running with a higher pump efficiency and lower turbine efficiency. An attempt to increase the round-trip efficiency by adding a multi stage submersible pump, resulted in additional ICC and LCC, which saw a decrease in profits.

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Bray, Laura. "Preparing for offshore renewable energy development in the Mediterranean." Thesis, University of Plymouth, 2017. http://hdl.handle.net/10026.1/10099.

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The development of offshore wind farms and marine renewable energy devices in the Mediterranean is central to both national, and international, energy strategies for countries bordering the Mediterranean Sea. The ecological impacts of marine renewable energy development in the Mediterranean region, although essential for policy makers, are as yet unknown. The Northern Adriatic is identified as a plausible site for offshore wind farm development. Using the wider region (Adriatic and Northern Ionian) as a case study, this thesis examines the likely impact to the marine environment if an offshore wind farm is established. Site suitability, based on wind speed, bathymetry, and larvae connectivity levels are investigated along with the plausibility of the turbines operating as artificial reefs in the area. As offshore wind farms may alter the larval connectivity and supply dynamics of benthic populations, a connectivity map was constructed to identify areas of high and low connectivity in the Adriatic Sea. The Puglia coast of Italy is a likely larval sink, and displays some of the highest connectivity within the region, suggesting potential inputs of genetic materials from surrounding populations. Considering offshore wind farms could operate as artificial reefs, an in-situ pilot project was established to simulate the presence of wind turbines. Macroinvertebrates colonized the new substrata within the first few months but were lower in abundance when compared to a natural hard substrata environment. Time, turbine location, and the material used for turbine construction all affected the macro-invertebrate communities. In addition, fish abundances, and diversity were lower around the simulated OWF foundations in comparison to a natural hard substrata environment, and no increases in fish abundance occurred around the simulated turbines when compared to reference sites of soft substrata. This observation was validated with the use of an ecosystem modelling software (Ecopath with Ecosim), which simulated the overall ecosystem level impacts that would occur if 50 offshore monopile wind turbines were introduced to the Northern Ionian and colonized by macroinvertebrate communities. When compared to the baseline scenario (no simulated introduction of an OWF), the introduction of new habitat had no discernible impacts to the structure or functioning of the marine ecosystem. Noticeable changes to the ecosystem were only apparent if fishing restrictions were enforced in parallel with the simulated offshore wind farm; the ecosystem appears to become more structured by top down predation. In addition seabirds are also impacted by the reduction of fishing discards as a food source. These results are the first attempt to quantify the suspected benefits of offshore wind farms operating as de-facto marine protected areas.

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Cotter, Oliver. "Installation of suction caisson foundations for offshore renewable energy structures." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534163.

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Perkins, Eben. "Shaping Our Energy Future: Lessons from Maine's Offshore Wind Energy Development Plans." Scholarship @ Claremont, 2011. http://scholarship.claremont.edu/pomona_theses/94.

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Maine is at a crossroads in its energy future. With 80 percent of homes in the state heated by oil, the highest percentage in the country, Mainers find themselves addicted to imported energy and without a renewable powered heating alternative for the long, harsh winters. Enter offshore wind into the equation. A relatively unknown technology in the United States, offshore wind farms are currently powering one million homes in Europe. Furthermore, the Gulf of Maine has world class wind resources that could potentially provide double the power production of the state’s current peak electricity demand. Through eight weeks of research conducted in Portland, Maine, which consisted of a literature review and stakeholder interviews, I have identified and focused on the key opportunities and obstacles to successful offshore wind energy development in Maine in the short and long term.

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Miron, Cristian. "Advanced control for renewable energy systems." Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1I064/document.

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De nos jours, l’énergie renouvelable est une solution durable pour remplacer les sources conventionnelles d’énergie. L’utilisation de réseaux photovoltaïques (PV) et d’éoliennes est devenue très populaire. Cependant, de cette énergie gratuite découlent de nouveaux défis. Certains des grands inconvénients de ces alternatives sont représentés par un faible taux de conversion de l'énergie et par la nécessité d'utiliser un système de stockage d'énergie Un autre bémol est aussi celui de l’efficacité réduite du transfert entre les réseaux PV et/ou les éoliennes, et les consommateurs. L’objectif de cette thèse est de présenter et de comparer différentes stratégies de commandes pour les systèmes alimentés par les sources d’énergies renouvelables. Un prototype destiné à des fins d’essais a été conçu. Cette thèse traite de différents aspects tels que la modélisation de panneaux PV, l’observateur non linéaire, un algorithme de contrôle basé sur une recherche du point de puissance maximum (Maximum modélisation d’un convertisseur abaisseur DC/DC,construire un Point Power Point Tracking), un algorithme de contrôle polynôme, la stabilité du système. Le chapitre 2 présente différents modèles de cellule photovoltaïque qui peuvent, en outre, être utilisés dans une boucle de contrôle. Une interface utilisateur graphique est créée pour faciliter le calcul de certains paramètres et de la courbe caractéristique de la tension voltage du panneau PV. De plus, un modèle à espace d’états et un modèle de fonction de transfert de certains convertisseurs DC/DC sont présentés. Le chapitre 3 se concentre sur l’élaboration d’un observateur Takagi-Sugeno (T-S) qui fournit la tension estimée du panneau PV. Ce dernier sera, plus tard, utilisé dans le bloc de commande ou pourra servir pour les diagnostics. Le chapitre 4 compare différents algorithmes MPPT classique, ainsi qu’un algorithme de contrôle avancé qui pourra être utilisé plus tard pour améliorer les performances des boucles de contrôles. Une étude de cas sur une commande de supervision utilisant une cellule à combustion est proposée. Le chapitre 5 est orienté vers une approche plus pratique. Il présente un système de contrôle distribué qui est géré via un serveur OPC. Un algorithme de control polynomial robuste R-S-Test élaboré, validé en simulation et testé sur une plateforme expérimentale. Un système d’acquisition de données enregistre les informations envoyées par chacune des boucles de contrôle et est capable de tracer les données en temps réel. Le chapitre 6 est dédié aux conclusions. Le chapitre 7 présente les codes des logiciels développés et certains schémas qui ont été utilisés durant les simulations. Le chapitre 8 liste la bibliographie
Nowadays renewable energy is a long term solution for replacing the conventional sources of energy. The use of photovoltaic (PV) arrays and wind turbines has become very popular. Nevertheless, this “free energy” arises new challenges. Some of the big inconveniences of these alternatives are represented by a low conversion rate of the energy and the necessity of using an energy storing system. Another drawback is the reduced transfer efficiency between the PV arrays or/and wind turbines and the consumers. The goal of this thesis is to present and compare different control strategies for systems that are powered by renewable sources of energy. A prototype for testing purposes was designed. This thesis treats different aspects such as PV panel modelling, buck converter modelling, building a non-linear observer, a control algorithm based on maximum power point tracking (MPPT), a polynomial control algorithm, the stability of the system. Chapter 2 presents different photovoltaic cell models that can be further used in control loops. A graphic user interface is created for facilitating the computation of certain parameters and of the power-voltage / current-voltage characteristics of a PV panel. Furthermore, a state space model and a transfer function model of some DC/DC converters are presented. Chapter 3 focuses on elaborating a Takagi-Sugeno (T-S) observer which will provide the estimated voltage of the PV panel. The latter will later be used in the control block or it can serve for diagnosis purposes. Chapter 4 compares different classical MPPT algorithms, as well as advanced control algorithms which may be later used to improve the performances of the control loops. A case study on a supervisory control that uses fuel cells is proposed. Chapter 5 is oriented on a rather practical approach. It presents a distributed control system that is managed via an OPC server. A robust R-S-T polynomial controller is designed, validated in simulation and tested on a prototype. A data acquisition system stores the data sent by each of the control loops and is able to plot data in real time. Chapter 6 is dedicated to the conclusions. Chapter 7 presents the code of the developed software and some schematics that were used during simulations. Chapter 8 lists the bibliography

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Miller, Raeanne Gwen. "Larval dispersal and population connectivity : implications for offshore renewable energy structures." Thesis, University of the Highlands and Islands, 2013. https://pure.uhi.ac.uk/portal/en/studentthesis/larval-dispersal-and-population-connectivity-implications-for-offshore-renewable-energy-structures(ee382e5b-0923-48f4-bc44-0e7ede647b3d).html.

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The installation of marine renewable energy devices (MREDs) is progressing rapidly along many coastlines. It has been suggested that MRED arrays could provide stepping-stones for larval dispersal, mediating species range expansions or invasions. As common members of hard-substrate fouling communities and likely colonisers of MREDs, the larval dispersal processes of barnacles (Cirripedia: Thoracia) in the Firth of Lorn (Scotland) are assessed at scales ranging from mm to 10s – 100s km. At the scale of the organism itself, significant differences in larval mass densities and sinking velocities were observed between species of cirripedes, suggesting that larval physiology and morphology play an important role in water column vertical positioning. The importance of vertical positioning to horizontal transport and dispersal of larvae was identified in field surveys of the horizontal and vertical distributions of cirripede larvae, which revealed the interplay of wind-driven and tidally-oscillating currents in determining transport distances. Numerical simulations of larval dispersal based on a threedimensional hydrodynamic model then demonstrated that larvae with shallower abundance distributions often experienced greater horizontal transport, but that net dispersal distances were often greater for larvae deeper in the water column. Overall, simulated transport and dispersal distances were greatest for particles released at habitats further from the coast, such as MREDs, suggesting that the connectivity of these adult populations may be enhanced. Together, larval morphology, vertical positioning, and the coastal proximity of adult habitat could serve as useful indicators of larvae capable of reaching nearby newly installed offshore structures. For locations designated for MRED development in the Firth of Lorn, it is suggested that species with dispersal abilities similar to the cirripedes in this study could feasibly use these structures as stepping-stones for dispersal and range expansion, which could have important consequences when fouling communities are comprised of commercially important or invasive species.

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Wilhelmsson, Dan. "Aspects of offshore renewable energy and the alterations of marine habitats /." Stockholm : Department of Zoology, Stockholm University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-31157.

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Sinha, Yashwant. "Optimisation of offshore wind farm maintenance." Thesis, Robert Gordon University, 2016. http://hdl.handle.net/10059/1572.

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The installed capacity of European Offshore Wind Turbines (OWT) is likely to rise from the 2014 value of 7GW to 150GW in 2030. However maintenance of OWT is facing unprecedented challenges and cost 35% of lifetime costs. This will be equivalent to £14billion/year by 2030 if current OWT maintenance schemes are not changed. However the complexities around OWT operation require tools and systems to optimise OWT maintenance. The design of optimal OWT maintenance requires failure analysis of over 10,000 components in OWT for which there is little published work relating to performance and failure. In this work, inspection reports of over 400 wind turbine gearboxes (source: Stork Technical Services) and SCADA data (source: Shetland Aerogenerators Ltd) were studied to identify issues with performance and failures in wind turbines. A modified framework of Failure Mode Effects and Criticality Analysis (i.e. FMECA+) was designed to analyse failures according to the unique requirements of OWT maintenance planners. The FMECA+ framework enables analysis and prediction of failures for varied root causes, and determines their consequences over short and long periods of time. A software tool has been developed around FMECA+ framework that enables prediction of component level failures for varied root causes. The tool currently stores over 800 such instances. The need to develop a FMECA+ based Enterprise Resource Planning tool has been identified and preliminary results obtained from its development have been shown. Such a software package will routinely manage OWT data, predict failures in components, manage resources and plan an optimal maintenance. This will solve some big problems that OWT maintenance planners currently face. This will also support the use of SCADA and condition monitoring data in planning OWT maintenance, something which has been difficult to manage for a long time.

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Martínez, Díaz Maria del Mar. "Stand-alone hybrid renewable energy systems (HRES)." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/457978.

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End of Energy Poverty and achieving Sustainable Energy for all by 2030 is a universal challenge. 1.3 billion people without energy access and 2.8 billion people using unsustainable solid fuel for cooking and heating are global challenges for human and societal sustainable development. Nearly $1 trillion of investment is expected in the Sustainable Energy for All (SE4ALL) scenario to achieve universal energy access in 2030. Around 60% of investments will be in isolated off-grid and mini-grid systems with the relevant goal of duplicating the renewable energy sources in the energy mix. Access to innovation trends in renewable energy off-grid would benefit future installations. This work brings to light the recent years research contributions in Hybrid Renewable Energy Systems (HRES) and related aspects that would benefit these required investments in isolated off-grid and mini-grid systems. An overview on the thematic focus of research in Hybrid Renewable Energy Systems (HRES) in the last decade, period 2005 - 2015, is provided. This review covers multiple key aspects of HRES as the main focus of the research (technical, economical, environmental, financial, etc.); the design of the system (type of load, energy sources, storage, availability of meteorology data, etc.); different optimization criteria and objective function; software and modelling tools; and the type of application and country among others. A methodology for searching, identifying and categorizing the innovations related to HRES is proposed. Applying this methodology during this PhD work results in a primary database with a categorized bibliography including nearly 400 entries. Currently system design is mainly technical driven with economic feasibility analysis regarding the energy cost. As for environmental aspects, the beneficial impacts of renewable energy are hardly introduced as an economical value that is so far the most important decision-making criteria. Regarding decision-making tools, the most currently used optimization algorithms and software tools for the design of HRES is HOMER and a case study for understanding is proposed. Following the analysis of most popular and relevant criteria, an easy to use guideline is proposed encouraging decision-making for more sustainable energy access. There are untapped research opportunities for HRES in multi-disciplinary thematic areas. The analysis of innovations regarding the system design for Hybrid Renewable Energy Systems (HRES) have identified potential for research community aligned with the trends to integrate the value chain and foster innovative business models and sustainable energy markets. After the analysis of those different focus that goes from technical and economical, to environmental, regulatory or policy aspects, an integrated value chain for HRES systems is defined. Knowledge, methodologies & tools are provided in this PhD work for more stand-alone hybrid systems creating value for more of the stakeholders involved. After reviewing the latest innovations in HRES per thematic focus, an integrated value chain for those systems has been proposed and multidisciplinary research opportunities have been identified. Identifying the need to include the environmental aspects in early stages of the decision-making has lead to propose an easy to use guideline integrating most relevant criteria for the design of stand-alone renewable power systems. Finally, the research opportunities identified and the untapped potential of transferring latest innovations have result in the creation of the website ElectrifyMe (www.electrifyme.org) to enable valuable international networking contacts among researchers and encouraging multi-disciplinary research. "Knowledge, methodologies & tools" are powerful contributions by research community and innovators to foster more sustainable energy for all.
El fi de la pobresa energètica i l'assoliment d'energia sostenible per a tothom l'any 2030 és un repte universal. 1,3 mil milions de persones sense accés a l'energia i 2,8 mil milions de persones que utilitzen combustible sòlid insostenible per cuinar i escalfar són desafiaments globals pel desenvolupament humà sostenible i social. S'espera una inversió aproximada de $1 trilió en l'energia sostenible per a tots (SE4ALL) per aconseguir l'accés universal a l'energia en 2030. Al voltant del 60 % de les inversions seran en sistemes off-grid i mini-grid, amb la corresponent meta de duplicar les fonts d'energia renovables en el mix energétic. En aquesta tesis es facilita una visió general sobre els àmbits temàtics de la recerca en Hybrid Renewable Energy Systems (HRES) en l'última dècada, període 2005-2015. Aquesta revisió es refereix a diversos aspectes clau deis HRES com: el focus principal de la investigació (tècnics, econòmics, ambientals, financers, etc.); el disseny del sistema (tipus de carrega, fonts d'energia, l'emmagatzematge, la disponibilitat de dades de meteorologia, etc.); diferents criteris d'optimització i funció objectiu; programari de modelatge eines; i el tipus d'aplicació i el país, entre d'altres. Es proposa una metodologia per buscar, identificar i categoritzar les innovacions relacionades amb els HRES. L'aplicació d'aquesta metodologia durant aquest treball de doctorat proporciona una base de dades primaria amb una bibliografia classificada incloent prop de 400 entrades. Actualment el disseny dels sistemes incorporen criteris tècnics amb anàlisi de viabilitat econòmica sobre el cost de l'energia. Pel que fa a les eines de presa de decisions, el métode d'optimització més utilitzats en l'actualitat pel disseny de HRES és HOMER, i es proposa un estudi de cas per a la comprensió deis criteris de disseny. Després de l'anàlisi de la majoria deis valors més habituals i rellevants, es proposa una senzilla guia per la presa de decisions per a l'accés a l'energia més sostenible. Després de compartir innovacions i proporcionar metodologies i eines, facilitar la creació de xarxes entre els investigadors ha demostrat ser una poderosa acció per promoure recerca sense explotar amb equips multidisciplinaris i internacionals. La pàgina web ElectrifyMe (www .electrifyme .org) ha estat creada amb la finalitat de facilitar a la comunitat d'investigació descobrir les innovacions i compartir projectes . Coneixements, metodologies i eines es proporcionen en aquest treball de doctorat per afavorir la creació de valor als sistemes aïllats híbrids renovables (stand-alone HRES) pels actors involucrats. Després de revisar les últimes innovacions en la introducció de renovables en sistemes aïllats en diferent enfoc temàtic, s'han estat identificat oportunitats de recerca multidisciplinars i s'ha proposat una cadena de valor integrada per aquests sistemes. La identificació de la necessitat d'incloure els aspectes ambientals en les primeres etapes de la presa de decisions ha portat a proposar una guia fàcil per utilitzar la integració de criteris més rellevants pel disseny de sistemes d'energia renovables independents. Finalment, tes oportunitats de recerca identificades i el potencial sense explotar de transferir les darreres innovacions tenen com a resultat la creació de la pàgina web ElectrifyMe (www.electrifyme.org) per promoure contactes i col·laboracions de xarxes internacionals entre investigadors i el foment de la investigació multidisciplinar. "El coneixement, les metodologies i les eines són poderoses contribucions de la comunitat de recerca per assolir un accés sostenible a l'energia per tots"

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Pfenninger, Stefan Johannes. "Multi-scale energy systems modeling of the renewable energy transition." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/43849.

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The majority of greenhouse gas emissions produced by mankind come from the burning of fossil fuels. Therefore, to prevent dangerous climate change, the world needs to completely rebuild the way it uses energy. This transformation is already underway and one of its key features is the rising importance of variable renewable energy, particularly wind and photovoltaics (PV). To better understand this transition, a new energy systems modeling framework is developed, called Calliope. Calliope is designed to deal with data of high spatial and temporal resolution, to run on high-performance computing clusters, to be easily extensible and re-usable and thus allow the rapid development of models targeted at specific problems. A high-resolution modeling system requires high-resolution input data, particularly for the potential power production from renewable power plants. Thus, a method is developed and presented to simulate PV plants by using both meteorological reanalysis and satellite-measured data. To validate these simulations, a database of measured power output data from real PV systems across Europe is built. These methods are applied to two cases. First, scenarios for the British power system with different combinations of three key technology groups -- renewables, nuclear and fossil fuels -- are examined with regards to their cost, emissions, their import dependence and diversity. The results show that costs are similar across a wide range of combinations but that interconnection, storage or clean dispatchable technologies are needed for renewables shares above 80%. Second, the ability of concentrating solar (CSP) and nuclear power plants to provide a stable (baseload) power supply are examined for the case of South Africa, showing that CSP plants have the potential to be cost-competitive, and likely preferable with regards to environmental and investment risks. The methods and results presented here are a contribution towards a better understanding of the energy transition, and by extension, towards improved energy policy and planning.

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Gammon, Rupert. "The integration of hydrogen energy storage with renewable energy systems." Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/7847.

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This thesis concerns the design, implementation and operation of a hydrogen energy storage facility that has been added to an existing renewable energy system at West Beacon Farm, Leicestershire, UK. The hydrogen system consists of an electrolyser, a pressurised gas store and fuel cells. At times of surplus electrical supply, the electrolyser converts electrical energy into chemical energy in the form of hydrogen. This hydrogen is stored until there is a shortage of electrical energy to power the loads on the system, at which point it is reconverted back to electricity by the process of reverse-electrolysis that takes place within a fuel cell. The renewable energy sources, supplying electrical power to domestic and office loads at the site, are photovoltaic, wind and micro-hydroelectric. This work is being carried out through a project, conceived and overseen by the author, known as the Hydrogen and Renewables Integration (HARI) project. The purpose of this study is to demonstrate and gain experience in the integration of hydrogen energy storage with renewable energy systems and, most importantly, to develop software models that could be used for the design of future systems of this type in a range of applications. Effective models have been created and verified against the real-world operation of the system. These models have been largely completed, although some minor details remain unfinished as the are dependant upon studies linked to this one which are yet to be concluded. Subject to some fine tuning that this would entail, then, the models can be used to design a stand-alone, integrated hydrogen and renewable energy system, where only the load profile and weather conditions of a site are known. Significant practical experience has been gained through the design, installation and two years' of operation of the system. Many important insights have been obtained in relation to the integration of the system and the design and operation of its components.

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Wiersma, Bouke. "Public acceptability of offshore renewable energy in Guernsey : using visual methods to investigate local energy deliberations." Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/21565.

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Public support for renewable energy projects is important in transitioning towards a more sustainable energy system. However, the literature investigating local energy acceptability has predominantly focused on understanding local opposition to single (wind) energy projects. As a result, it has relatively little to say about the construction of support for such projects, and about the relative acceptability of other local contributions to sustainability. Also, by focusing on oppositional responses to energy projects, the willingness and ability of local communities to contribute constructively to the design of locally-supported energy developments has also been overlooked by many previous studies. In response to these limitations, this research adopted a focus on early stage ‘upstream’ deliberation of multiple local energy alternatives, using the British island of Guernsey as a case study. Informed by social representations theory, three studies investigated how potential future offshore wind, tidal and wave energy projects were represented by Guernsey residents to threaten, enhance or fit place-related values and meanings associated with Guernsey and its coast and sea. Working collaboratively with the Guernsey government’s Renewable Energy Team, a mixed methods approach with a focus on participatory, visual methods was adopted, including auto-photography (Study 1), deliberative focus groups (Study 2) and a questionnaire survey (Study 3). The research found Guernsey and its coast and sea to be meaningful to local residents in many ways and at different scales, including as a unique island in need of more independence, with a coast that is valued for its quietness, wildlife, leisure opportunities, tides, natural beauty and as a space for exploration. Public understandings of tidal and wave energy as a local energy option were highly diverse, and subsequently some but not all local offshore renewable energy options were represented as ‘fitting’ these place-related meanings. In particular, the notion of Guernsey’s local distinctiveness was found to be important; tidal energy projects were represented as enhancing this distinctiveness, while offshore wind energy was instead portrayed as making Guernsey more like everywhere else. Overall, local energy acceptance at such an upstream stage was found to depend to a substantial extent on the technology chosen, the selected site for the project, and on how the project is interpreted relationally within a context of wider energy systems, policies and the perceived availability of (more appealing) local alternatives. This thesis suggests that adopting an upstream, visual, place-based approach could be one way to both achieve a better academic understanding of the acceptability of local energy projects, and to contribute to the development of more acceptable energy development practices in the future.

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Naqvi, Syed Kazim. "Scale Model Experiments on Floating Offshore Wind Turbines." Digital WPI, 2012. https://digitalcommons.wpi.edu/etd-theses/1196.

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This research focuses on studying the feasibility of placing large wind turbines on deep-ocean platforms. Water tank studies have been conducted using the facilities at Alden Research Laboratories (ARL) on 100:1 scale Tension Leg Platform (TLP) and Spar Buoy (SB) models. Froude scaling was used for modeling the offshore wind turbine designs. Primary components of the platform turbine, tower, and cable attachments were fabricated in ABS plastic using rapid prototyping. A wireless data acquisition system was installed to prevent umbilical data cables from affecting the behavior of the platform when exposed to wave loading. In Phase I testing, Froude-scaled TLP and Spar Buoy models at a 100:1 scale were placed in a water flume and exposed to periodic waves at amplitudes ranging from 0.5 cm - 7.5 cm and frequencies ranging from 0.25 Hz - 1.5 Hz. The testing was conducted on simple tower and turbine models that only accounted for turbine weight at the nacelle. In Phase II testing, emphasis was placed on further testing of the tension leg platform as a more viable design for floating offshore wind turbines. The tension leg platform scale model was improved by adding a disc to simulate drag force incident at the top of the tower, as well as a rotor and blades to simulate the gyroscopic force due to turbine blade rotation at the top of the tower. Periodic wave motions of known amplitude and frequency were imposed on the model to study pitch, heave, roll, surge, sway motions and mooring cable tensions (in Phase II only) using accelerometers, inclinometers, capacitance wave gage, and load cells. Signal analysis and filtering techniques were used to refine the obtained data, and a Fourier analysis was conducted to study the dominant frequencies. Finally, Response Amplitude Operators (RAO's) were plotted for each data set to standardize the results and study the overall trend with respect to changes in wave amplitude and frequency. For Phase I testing, it is shown that surge motion of the platform dominates other motions for both the tension leg platform and spar buoy, and varying tether pretension has little effect on response amplitude operator values. For phase II testing, it was found that the introduction of thrust and gyroscopic forces increases sway and pitch motions as well as upstream tether forces. Coupling effects of pitch motion with roll and sway due to the presence of gyroscopic forces were also seen. The present experimental results can be used to validate the hydrodynamic kernels of linear frequency-domain models, time-domain dynamics models, and computational simulations on floating wind turbines. Numerical analysis and simulations have been conducted in a separate study at WPI. These simulations are comparable to the experimental results.

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Sterner, Michael [Verfasser]. "Bioenergy and renewable power methane in integrated 100% renewable energy systems. Limiting global warming by transforming energy systems / Michael Sterner." Kassel : Kassel University Press, 2009. http://d-nb.info/1011714493/34.

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Kusakana, Kanzumba. "Optimal operation control of hybrid renewable energy systems." Thesis, Bloemfontein: Central University of Technology, Free State, 2014. http://hdl.handle.net/11462/670.

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Thesis (D. Tech. (Electrical Engineering)) -- Central University of Technology, Free State, 2014
For a sustainable and clean electricity production in isolated rural areas, renewable energies appear to be the most suitable and usable supply options. Apart from all being renewable and sustainable, each of the renewable energy sources has its specific characteristics and advantages that make it well suited for specific applications and locations. Solar photovoltaic and wind turbines are well established and are currently the mostly used renewable energy sources for electricity generation in small-scale rural applications. However, for areas in which adequate water resources are available, micro-hydro is the best supply option compared to other renewable resources in terms of cost of energy produced. Apart from being capital-cost-intensive, the other main disadvantages of the renewable energy technologies are their resource-dependent output powers and their strong reliance on weather and climatic conditions. Therefore, they cannot continuously match the fluctuating load energy requirements each and every time. Standalone diesel generators, on the other hand, have low initial capital costs and can generate electricity on demand, but their operation and maintenance costs are very high, especially when they run at partial loads. In order for the renewable sources to respond reliably to the load energy requirements, they can be combined in a hybrid energy system with back-up diesel generator and energy storage systems. The most important feature of such a hybrid system is to generate energy at any time by optimally using all available energy sources. The fact that the renewable resources available at a given site are a function of the season of the year implies that the fraction of the energy provided to the load is not constant. This means that for hybrid systems comprising diesel generator, renewable sources and battery storage in their architecture, the renewable energy fraction and the energy storage capacity are projected to have a significant impact on the diesel generator fuel consumption, depending on the complex interaction between the daily variation of renewable resources and the non-linear load demand. V This was the context on which this research was based, aiming to develop a tool to minimize the daily operation costs of standalone hybrid systems. However, the complexity of this problem is of an extremely high mathematical degree due to the non-linearity of the load demand as well as the non-linearity of the renewable resources profiles. Unlike the algorithms already developed, the objective was to develop a tool that could minimize the diesel generator control variables while maximizing the hydro, wind, solar and battery control variables resulting in saving fuel and operation costs. An innovative and powerful optimization model was then developed capable of efficiently dealing with these types of problems. The hybrid system optimal operation control model has been simulated using fmincon interior-point in MATLAB. Using realistic and actual data for several case studies, the developed model has been successfully used to analyse the complex interaction between the daily non-linear load, the non-linear renewable resources as well as the battery dynamic, and their impact on the hybrid system’s daily operation cost minimization. The model developed, as well as the solver and algorithm used in this work, have low computational requirements for achieving results within a reasonable time, therefore this can be seen as a faster and more accurate optimization tool.

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Aldaouab, Ibrahim. "Optimization and Control of Smart Renewable Energy Systems." University of Dayton / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1567770026080553.

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Awodiji, Olurotimi Olakunle. "Integration of renewable energy into Nigerian power systems." Doctoral thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/27010.

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Many countries are advancing down the road of electricity privatization, deregulation, and competition as a solution to their growing electricity demand and other challenges posed by the monopolistic nature of the existing structure. Presently, Nigeria has a supply deficit of electricity as a result of the growing demand. This imbalance has negatively affected the economy of the country and the social-economic well-being of the population. Hence, there is an urgent need to reform the power sector for greater efficiency and better performance. The objectives of the reform are to meet the growing power demand by increasing the electric power generation and also by increasing competitiveness through the participation of more private sector entities. The renewable energy integration is one way of increasing the electricity generation in the country in order to cater for the growing demand adequately. Examples of the renewable energy that is available in the country include wind, geothermal, solar and hydro. They are considered to be environmentally friendly, replenishable and do not contribute to the climate change phenomena. The country presently generates the bulk of its electricity from both thermal (85%) and hydroelectric (15%) power plants. While electricity generation from the thermal power stations constitutes the largest share of greenhouse emission, this is mostly from burning coal and natural gas. The effect of this high proportion of greenhouse emission causes climate change which is referred to as a variation in the climate system statistical properties over a long period of time. It has been observed that many of the activities of human beings are contributory factors to the release of these greenhouse gases (GHG). But, as the traditional sources of energy continue to threaten the present and future existence on the planet earth, it is, therefore, imperative to increase the integration of the variable renewable energy sources in a sustainable and eco-friendly manner over a long period of time. The variability and the uncertainties of the renewable energy source's output, present a major challenge in the design of an efficient electricity market in a deregulated environment. The system deregulation and the use of renewable sources for the generation of electricity are major changes presently being experienced in power system. In a deregulated power system, the integration of renewable generation and its penetration affects both the physical and the economic operations. The main focus of this research is on the integration of wind energy into Nigerian power systems. Up till now, research on the availability of the wind energy and its economic impacts has been limited in Nigeria. Generally, the previous study of wind energy availability in Nigeria has been limited in scope. The wind energy assessment study has not been detailed enough to be able to ascertain the wind energy potential of the country. To cope with this shortcoming, a detailed statistical wind modeling and forecasting methodology have been used in this thesis to determine the amount of extractable wind energy in six selected locations in Nigeria using historical wind speed data for 30 years. The accuracy test of the statistical models was also carried using the Mean Absolute Error (MAE), Root Mean Square Error (RMSE), and Chi-Square methods to determine the inherent error margin in the modeling and analysis. It is found that the error margin of the evaluations falls within the expected permissible tolerance range. For a more detailed wind assessment study of the Nigeria weather, the seasonal variation of the weather conditions as it affects the wind speed and availability during the two major seasons of dry and rainy was considered. A Self-Adaptive Differential Evolution (SADE) was used to solve the economic load dispatch problem that considers the valve-point effects and the transmission losses subject to many constraints. The results obtained were compared with those obtained using the "standard" Differential Evolution (DE), Genetic Algorithm (GA), and traditional Gradient Descent method. The results of the SADE obtained when compared with the GA, DE, and Gradient descent show the superiority of SADE over all the other methods. The research work shows that the wind energy is available in commercial quantity for generation of electricity in Nigeria. And, if tapped would help reduce the gap between the demand and supply of electricity in the country. It was also demonstrated that the wind energy integration into the power systems affects the generators total production cost.

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Alsumiri, Mohammed. "Sliding mode control of renewable energy generation systems." Thesis, University of Liverpool, 2015. http://livrepository.liverpool.ac.uk/2014521/.

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As a result of decades of research and innovation in the renewable energy industry, advanced technologies have been developed for both wind and solar energy conversion systems. However, there are still some aspects of the systems that need to be enhanced to enable maximum and cost effective energy conversion. Wind is emerging as an alternative source for electrical power generation. Small-scale wind power generation system applications are becoming widespread because of rising fuel prices and the demand for reducing carbon emission. For such applications, vertical axis wind turbines (VAWT) appeal due to their ability to capture wind from different directions and their low noise-pollution. Wind energy and its conversion system are studied first. The need for advanced maximum power point tracking (MPPT) controllers is discussed in literature focusing on widely implemented algorithms. Sliding mode control theory has been studied and implemented in controlling wind power generation system (WPGS). The dynamic performance of the WPGS using sliding mode control has shown improved dynamic performance, overshoot errors eliminations and higher energy conversion ratios than the widely used proportional integral (PI) control. A new approach in WPGS control strategy by development of a novel soft control strategy based on the mathematical residue theorem has been introduced. The idea of using the residue theorem is to set a soft dynamic boundary for controlled variables around a reference point, so that controlled variables lie on a point inside this boundary. The stability of the system has been ensured by following the Forward Euler method. The developed control strategy has been implemented in different control techniques of a small-scale permanent magnet synchronous generator (PMSG) based WPGS. The introduction of the new control approach based on residue theorem has further improved the energy conversion ratio by 2:5%. Moreover, a wind speed estimation algorithm is provided and implemented to the proposed controllers to overcome the wind speed measurements issues, i.e. cost and accuracy. Furthermore, an improved back-EMF observer based on residual theorem has been designed to estimate the mechanical rotor speed of the PMSG using the stator current and voltage measurements. The improved back-EMF observer has overcome the well-known limitation of the classical back-EMF at low speed observation. In addition, the wind speed has been estimated using the calculated power obtained from the PMSG voltage and current measurements as well as the estimated rotor speed. Based on the wind and rotor speeds, the tip speed ratio (TSR) is calculated and controlled to its optimal value. A MPPT controller has been developed for photovoltaic power generation systems based on a sliding mode control scheme in stand-alone configuration. The developed controller provides a solution to atmospheric conditions measurement issues and it enhances the efficiency of the PV power system. In addition, the developed controller overcomes the power oscillation around the operating point which appears in most implemented MPPT techniques. The MPPT operation is achieved by regulating the input voltage of the PV system using DC-DC boost converter topology. Moreover, a single-ended primary inductor converter (SEPIC) topology has been employed in PV power systems. The restrictions on the application of SEPIC have been solved based on sliding mode control. The efficiency of the PV system has significantly improved.

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Jaramillo, López Fernando. "Control and Model Identification on Renewable Energy Systems." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112240.

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La situation compromettante de l'environnement due à la pollution, et les coûts élevés des combustibles fossiles ont engagé des nouvelles politiques et réglementations et ont fortement incité l’augmentation de l’utilisation de nouvelles sources d'énergie renouvelables. De nombreux pays dans le monde ont augmenté de façon importante le développement de ces sources d'énergie. Deux des systèmes d'énergies renouvelables les plus couramment utilisés sont les systèmes éoliens (SE) et les systèmes photovoltaïques (SP). SE convertissent l'énergie du vent en énergie électrique au moyen d'un processus électromécanique et SP convertissent directement l'énergie solaire en énergie électrique au moyen d'un processus semi-conducteur. Ces systèmes présentent de nombreux défis qui doivent être résolus afin de gagner du terrain sur les systèmes d'énergies traditionnelles. L'un de ces défis est d'augmenter l'efficacité du système avec la commande des éléments de puissance. Afin d'atteindre cet objectif, il est nécessaire de mieux comprendre le comportement dynamique de ces systèmes et de développer des nouveaux modèles mathématiques et des nouvelles techniques de commande. Ces techniques nécessitent souvent des informations du système qui ne sont pas disponibles --- ou sont trop chères si on devait les mesurer. Pour résoudre ce problème, il est nécessaire de créer des algorithmes qui puissent estimer cette information, cependant, ce n'est pas une tâche facile, car les signaux des sources d'énergie dans SE et SP (c.-à-d. la vitesse du vent, rayonnement solaire, température) entrent dans les modèles mathématiques par une relation non linéaire. Ces algorithmes doivent pouvoir estimer ces signaux --- ou les signaux qui dépendent d’eux--- avec une bonne précision. Aussi, il est nécessaire de concevoir des lois de commande qui opèrent les systèmes à leur point maximum de puissance. Dans ce travail, nous proposons des nouveaux algorithmes d'estimation et des lois de commande qui sont liés à l'augmentation de l'efficacité énergétique dans SE et SP. Des travaux antérieurs liés à l'estimation des signaux mentionnés, les considéraient comme constants. Dans cette thèse, les algorithmes d'estimation proposés considèrent l'état variable des ces signaux. Dans toutes ces nouvelles propositions, la stabilité asymptotique est prouvée en utilisant les théories de Lyapunov. Les lois de commande sont calculées en utilisant les modèles non linéaires des systèmes. En outre, certaines des ces solutions sont étendues au cas général, qui peut être utilisé sur une large classe des systèmes non linéaires. Le premier, est un estimateur de paramètres pour les systèmes non linéaires. Il permet d'estimer les paramètres non linéaires variant dans le temps. La deuxième proposition est la conception d’un schéma pour une classe de systèmes non linéaires adaptatifs qui permet de compenser les incertitudes et les perturbations qui satisfont à la "condition de correspondance"
The compromising situation of the environment due to pollution, and the high costs of the fossil fuels have originated new policies and regulations that have stimulating the interest on alternative energy sources. Many countries around the world have increased in an important way the penetration of these energy sources. Two of the most widely used renewable energy systems are the wind turbines systems (WTS) and the photovoltaic systems (PVS). WTS convert wind energy in electric energy by means of an electromechanical process and PVS convert solar energy directly in electric energy by means of a semiconductive process. These systems show many challenges that need to be solved in order to gain ground to the traditional energy systems. One of these challenges is increase the overall system efficiency by controlling the power conditioning elements. In order to achieve this, is necessary to better understand the dynamic behavior of these systems and develop new mathematical models and new control techniques. These techniques often require system information that is not possible ---or is too expensive--- measure. In order to solve this problem, is necessary to create algorithms that are able to estimate this information, however, this is not an easy task, because the signals of the energy sources in WTS and PVS (i.e., wind speed, irradiance, temperature) enter in the mathematical models in a nonlinear relation. These algorithms have to be able to estimate these signals ---or the signals that depend on them--- with good precision. Also, it is necessary to design control laws that operate the systems at their maximum power point. In this work, we propose novel estimation algorithms and control laws that are related with the increase of the energetic efficiency in WTS and PVS. Previous works related with estimation of the mentioned signals considered them as constants. In this thesis, the proposed estimation algorithms consider the time-varying condition of these signals. In all of these novel propositions, uniform asymptotic stability is proved using Lyapunov theories. The control laws are derived using the overall nonlinear models of the systems. In addition, some of these solutions are extended to the general case, which can be used on a large-class of nonlinear systems. The first one, is a novel parameter estimator for nonlinear systems. It allows to estimate time-varying nonlinear parameters. The second general proposition is a framework for a class of adaptive nonlinear systems that allows to compensate for uncertainties and perturbations that satisfy the matching condition

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26

Nielsen, Knut Erik. "Superconducting magnetic energy storage in power systems with renewable energy sources." Thesis, Norwegian University of Science and Technology, Department of Electrical Power Engineering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-10817.

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The increasing focus on large scale integration of new renewable energy sources like wind power and wave power introduces the need for energy storage. Superconducting Magnetic Energy Storage (SMES) is a promising alternative for active power compensation. Having high efficiency, very fast response time and high power capability it is ideal for levelling fast fluctuations. This thesis investigates the feasibility of a current source converter as a power conditioning system for SMES applications. The current source converter is compared with the voltage source converter solution from the project thesis. A control system is developed for the converter. The modulation technique is also investigated. The SMES is connected in shunt with an induction generator, and is facing a stiff network. The objective of the SMES is to compensate for power fluctuations from the induction generator due to variations in wind speed. The converter is controlled by a PI-regulator and a current compensation technique deduced from abc-theory. Simulations on the system are carried out using the software PSIM. The simulations have proved that the SMES works as both an active and reactive power compensator and smoothes power delivery to the grid. The converter does however not seem like an optimum solution at the moment. High harmonic distortion of the output currents is the main reason for this. However this system might be interesting for low power applications like wave power. I

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27

Younes, George. "Integration of offshore renewable energy sources for the production of chemical energy vectors: The case of Hydrogen." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.

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Energy is the fuel that drives our economies. Energy demand is on the rise, and so the challenge of meeting the needs for safer, more efficient, and environmentally friendly solutions. With the aim of staying below the 2℃ scenario and agreeing with the 2015 Paris agreement and the European Union 2050 Green Deal, further action is required to ensure a smooth energy transition. In the offshore context the challenge persists, as renewable energy is weather and climate dependent, but represents a great opportunity for energy transition. For these reasons, along with the latest oil crisis due to Covid-19 in 2020, the term hydrogen economy and methanol economy are once again on the rise. In this work, not only hydrogen is discussed, but additional potential energy vectors are presented as well, with particular attention to the possible offshore exploitation. The integration of energy sources paves the way for the Power to Gas (P2G) concept namely hydrogen, not only as a potential fuel but also a feedstock, as well as synthetic natural gas (SNG) and Synthesis gas (Syngas). This integration also leads to the Power to Liquid (P2L) concept compromising mainly the synthesis of methanol, dimethyl ether (DME), Fischer Tropsch liquids, and ammonia energy vectors. Hence, the different routes leading to the production of each and every mentioned energy vector is presented, explained, and discussed within the offshore context; followed by a Technology Readiness Level assessment (TRL) for each process. Considering that hydrogen can be both the potential ‘fuel of the future’ and a feedstock for the production of almost all the mentioned energy vectors, it constitutes the main topic of this paper. Hydrogen production alternatives are discussed and a simulation of water electrolysis is done for both alkaline electrolysis and Proton Exchange Membrane (PEM) electrolysis using a commercial software leading to the deduction of the overall system efficiency for each of the simulated processes.

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28

Smith, Nicola Anne Visocchi. "Decision support for new and renewable energy systems deployment." Thesis, University of Strathclyde, 2002. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21192.

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The global requirement for sustainable energy provision will become increasingly important over the next fifty years as the environmental effects of fossil fuel use become apparent. Therefore, the issues surrounding integration of renewable energy supplies need to be considered carefully. The focus of this work was the development of a decision support framework that will aid the design of sustainable energy systems for the supply of electricity, heat, hot water and fuel for transportation. Issues requiring consideration in high percentage renewable energy systems include the reliability of the supply when intermittent sources of electricity are being used, and the subsequent necessity for storage and back-up generation. In order to allow the modelling of realistic integrated systems that supply the total energy needs of an area, the production of fuels derived from biomass and waste and their use in a variety of different plant types (e. g. vehicles, engines, turbines, fuel cells, electrolysers, heating and hot water storage systems) is an important consideration. The temporal nature of both intermittent electricity and derived fuel supplies must be taken into account in any analysis. Existing demand and supply matching software has been enhanced to allow the full analysis described. Generic algorithms have been developed to allow the behaviour of a comprehensive list of plant types and methods for producing derived fuels to be modelled, which require only available process and manufacturers' data. The program is flexible, generic and easy to use, allowing a variety of supply strategies to be analysed. This has been shown through the study of a small Scottish island, which highlights the importance of derived fuel production and use. This work has succeeded in developing a more complete tool for analysing the feasibility of integrated renewable energy systems. This will allow informed decisions to be made about the technical feasibility of supply mix and control strategies, plant type and sizing, suitable fuel production, and fuel and energy storage sizing, for any given area and range of supply options.

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29

Rivano, Giuseppina. "Analysis of offshore hybrid energy systems for improved dispatchability of wave energy." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.

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Attualmente è riscontrabile a livello globale un aumento del numero di giacimenti offshore contenenti un piccolo quantitativo di gas a bassa pressione e dunque destinati ad essere avviati alla procedura finale di chiusura. Per eliminare gli elevati costi di trasporto del gas e valorizzare il sito, nasce il concetto di Gas-to-Wire. Esso consiste nella produzione di elettricità attraverso la combustione del gas naturale in sito. Allo stesso tempo, la consapevolezza che le risorse oil & gas sono destinate ad estinguersi con gli anni ha spinto la comunità scientifica a concentrare l’attenzione su nuove forme di energia rinnovabile, come le onde marine. Nonostante ciò, vi sono ancora delle barriere da abbattere legate sia al prezzo di tali tecnologie che alla produzione di energia in modo discontinuo che rende problematica la loro integrazione nella rete elettrica. Al fine di superare tali problematiche, si è pensato di adottare un sistema ibrido di energia offshore costituito da convertitori di onda e microturbine a gas installate sulla piattaforma presente nel giacimento depleto. Esse forniscono potenza addizionale di bilanciamento sfruttando il concetto di Gas-to-Wire, consentendo una maggiore dispacciabilità dell’energia rinnovabile da onde. Lo scopo del presente lavoro è quello di analizzare le prestazioni energetiche, economiche e d’impatto ambientale del sistema ibrido di energia offshore. Due differenti siti, Mare del Nord e Mar Adriatico, sono stati presi in considerazione al fine di valutare l’influenza delle diverse condizioni meteo-marine, diversi mercati elettrici di dispacciamento e diversi incentivi fiscali per l’integrazione di energia rinnovabile sulle prestazioni del sistema ibrido di energia offshore. Attraverso l’approccio seguito per il dimensionamento e gestione dei due sistemi ibridi, è stato possibile calcolare gli indicatori tecnici, ambientali ed economici.

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30

Murray, William Norman. "Energy wheeling viability of distributed renewable energy for industry." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2730.

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Thesis (Master of Engineering in Electrical Engineering))--Cape Peninsula University of Technology, 2018.
Industry, which forms the lifeblood of South Africa’s economy, is under threat as a result of increased electricity pricing and unstable supply. Wheeling of energy, which is a method to transport electricity generated from an Independent Power Producer (IPP) to an industrial consumer via the utility’s network, could potentially address this problem. Unlike South Africa’s electricity landscape, which is highly regulated and monopolized by Eskom, most developed countries have deregulated their electricity market, which has led to greater competition for electricity supply. This thesis, presents an evaluation of the economic viability and technical concerns arising from third party transportation of energy between an IPP and an industrial consumer. IPP’s are able to generate electricity from various renewable distributed generation (DG) sources, which are often physically removed from the load. In practice, electricity could be generated by an IPP and connected to a nearby Main Transmission Substation (MTS) in a region with high solar, wind or hydropower resources and sold to off-takers a few hundred kilometres away. Using two software simulation packages, technical and economic analysis have been conducted based on load data from two industrial sites, to determine the viability of wheeling energy between an IPP and off-taker. The viability will be evaluated based on levelized cost of electricity (LCOE); net present cost (NPC); DG technology; distance from the load; available renewable resources; impact on voltage profile, fault contribution, thermal loading of the equipment and power loss. The results from both case studies show that the impact of DG on the voltage profile is negligible. The greatest impact on voltage profile was found to be at the site closest to the load. Asynchronous and synchronous generators have a greater fault contribution than inverter-based DG. The fault contribution is proportional to the distance from the load. Overall, thermal loading of lines increased marginally, but decreased based on distances from the load. Power loss on short lines is negligible but there is a significant loss on the line between the load and DG based on the distance from the load. Electricity generated from wind power is the most viable based on LCOE and NPC. For larger wind systems, as illustrated by the second case study, grid parity has already been reached. Wheeling of wind energy has already proven to be an economically viable option. According to future cost projection, large scale solar energy will become viable by 2019. The concept of wheeling energy between an IPP and off-taker has technical and economic merit. Wheeling charges are perceived to be high, but this is not the case as wheeling tariffs consist of standard network charges. In the future, renewable energy will continue to mature based on technology and cost. Solar energy, including lithium-ion battery back-up technology, looks promising based on future cost projections. Deregulation of the electricity market holds the key to the successful implementation of energy wheeling as it will open the market up for greater competition.

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Cuadrado, Guevara Marlyn Dayana. "Multistage scenario trees generation for renewable energy systems optimization." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/670251.

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The presence of renewables in energy systems optimization have generated a high level of uncertainty in the data, which has led to a need for applying stochastic optimization to modelling problems with this characteristic. The method followed in this thesis is multistage Stochastic Programming (MSP). Central to MSP is the idea of representing uncertainty (which, in this case, is modelled with a stochastic process) using scenario trees. In this thesis, we developed a methodology that starts with available historical data; generates a set of scenarios for each random variable of the MSP model; define individual scenarios that are used to build the initial stochastic process (as a fan or an initial scenario tree); and builds the final scenario trees that are the approximation of the stochastic process. The methodology proposes consists of two phases. In the first phase, we developed a procedure similar to Muñoz et al. (2013), with the difference being that the VAR models are used to predict the next day for each random parameter of the MSP models. In the second phase, we build scenario trees from the Forward Tree Construction Algorithm(FTCA), developed by Heitsch and Römisch (2009a); and an adapted version of DynamicTree Generation with a Flexible Bushiness Algorithm (DTGFBA), developed by Pflugand Pichler (2014, 2015). This methodology was used to generate scenario trees for two MSP models. A first model, Multistage Stochastic Wind Battery Virtual Power Plantmodel (MSWBVPP model) and to a second model, which is the Multistage StochasticOptimal Operation of Distribution Networks model (MSOODN model). We developed extensive computational experiments for the MSWBVPP model and generated scenario trees with real data, which were based on MIBEL prices and wind power generation of the real wind farm called Espina, located in Spain. For the MSOODN model, we obtained scenario trees by also using real data from the power load provided by FEEC-UNICAMP and photovoltaic generation of a distribution grid located in Brazil. The results show that the scenario tree generation methodology proposed in this thesis can obtain suitable scenario trees for each MSP model. In addition, results were obtained for the model using the scenario trees as input data. In the case of the MSWBVPP model, we solved three different case studies corresponding to three different hypotheses on the virtual power plant’s participation in electricity markets. In the case of the MSOODN model, two test cases were solved, with the results indicating that the EDN satisfied the limits imposed for each test case. Furthermore, the BESS case gave good results when taking into account the uncertainty in the model. Finally, the MSWBVPP model was used to study the relative performance of the FTCA and DTGFBA scenario trees, specifically by analyzing the value of the stochastic solution for the 366 daily optimal bidding problems. To this end, a variation of the classical VSS (the so-called “Forecasted Value of the Stochastic Solution”, FVSS) was defined and used together with the classical VSS.
a presencia de energías renovables en la optimización de sistemas energéticos hagenerado un alto nivel de incertidumbre en los datos, lo que ha llevado a la necesidad de aplicar técnicas de optimización estocástica para modelar problemas con estas características. El método empleado en esta tesis es programación estocástica multietapa (MSP, por sus siglas en inglés). La idea central de MSP es representar la incertidumbre (que en este caso es modelada mediante un proceso estocástico), mediante un árbol de escenarios. En esta tesis, desarrollamos una metodología que parte de una data histórica, la cual está disponible; generamos un conjunto de escenarios por cada variable aleatoria del modelo MSP; definimos escenarios individuales, que luego serán usados para construir el proceso estocástico inicial (como un fan o un árbol de escenario inicial); y, por último, construimos el árbol de escenario final, el cual es la aproximación del proceso estocástico. La metodología propuesta consta de dos fases. En la primera fase, desarrollamos un procedimiento similar a Muñoz et al. (2013), con la diferencia de que para las predicciones del próximo día para cada variable aleatoria del modelo MSP usamos modelos VAR. En la segunda fase construimos árboles de escenarios mediante el "Forward Tree Construction Algorithm (FTCA)", desarrollado por Heitsch and Römisch (2009a); y una versión adaptada del "Dynamic Tree Generation with a Flexible Bushiness Algorithm (DTGFBA)", desarrolado por Pflug and Pichler (2014, 2015). Esta metodología fue usada para generar árboles de escenarios para dos modelos MSP. El primer modelo fue el "Multistage Stochastic Wind Battery Virtual Power Plant model (modelo MSWBVPP)", y el segundo modelo es el "Multistage Stochastic Optimal Operation of Distribution Networks model (MSOODN model)". Para el modelo MSWBVPP desarrollamos extensivos experimentos computacionales y generamos árboles de escenarios a partir de datos realesde precios MIBEL y generación eólica de una granja eólica llamada Espina, ubicada en España. Para el modelo MSOODN obtuvimos árboles de escenarios basados en datos reales de carga, provistos por FEEC-UNICAMP y de generación fotovoltaica de una red de distribución localizada en Brasil. Los resultados muestran que la metodología de generación de árboles de escenarios propuesta en esta tesis, permite obtener árboles de escenarios adecuados para cada modelo MSP. Adicionalmente, obtuvimos resultados para los modelos MSP usando como datos de entrada los árboles de escenarios. En el caso del modelo MSWBVPP, resolvimos tres casos de estudio correspondiente a tres hipótesis basadas en la participación de una VPP en los mercados de energía. En el caso del modelo MSOODN, dos casos de prueba fueron resueltos, mostrando que la EDN satisface los límites impuestos para cada caso de prueba, y además, que el caso con BESS da mejores resultados cuando se toma en cuenta el valor la incertidumbre en el modelo. Finalmente, el modelo MSWBVPP fue usado para estudiar el desempeño relativo de los árboles de escenarios FTCA y DTGFBA, específicamente, analizando el valor de la solución estocástica para los 366 problemas de oferta óptima. Para tal fin, una variación del clásico VSS (denominado "Forecasted Value of the Stochastic Solution", FVSS) fue definido y usado junto al clásico VSS.

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32

Morgan, Tomos Rhys. "The performance and optimisation of autonomous renewable energy systems." Thesis, Cardiff University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289463.

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33

Darabi, Sahneh Faryad. "Non-model based adaptive control of renewable energy systems." Thesis, Kansas State University, 2010. http://hdl.handle.net/2097/7044.

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Master of Science
Department of Mechanical and Nuclear Engineering
Guoqiang Hu
In some types of renewable energy systems such as wind turbines or solar power plants, the optimal operating conditions are influenced by the intermittent nature of these energies. This fact, along with the modeling difficulties of such systems, provides incentive to look for non-model based adaptive techniques to address the maximum power point tracking (MPPT) problem. In this thesis, a novel extremum seeking algorithm is proposed for systems where the optimal point and the optimal value of the cost function are allowed to be time varying. A sinusoidal perturbation based technique is used to estimate the gradient of the cost function. Afterwards, a robust optimization method is developed to drive the system to its optimal point. Since this method does not require any knowledge about the dynamic system or the structure of the input-to-output mapping, it is considered to be a non-model based adaptive technique. The proposed method is then employed for maximizing the energy capture from the wind in a variable speed wind turbine. It is shown that without any measurements of wind velocity or power, the proposed method can drive the wind turbine to the optimal operating point. The generated power is observed to be very close to the maximum possible values.

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Taylor, Philip Charles. "Distributed intelligent load control of autonomous renewable energy systems." Thesis, University of Manchester, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.550559.

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A number of load control techniques and technologies have already been developed for autonomous power systems but no single technique has been widely adopted. Many of these load control systems have been partially successful but have suffered from a number of limitations that were addressed as part of this project. This thesis describes the development of distributed intelligent load controllers designed to address the limitations of previous load control solutions. A self-tuning fuzzy controller was developed to improve the power quality and efficiency of autonomous renewable energy systems. A laboratory wind-diesel test rig was developed to aid the design and testing of the load controller hardware and software. Computer models of wind powered and wind-diesel powered networks were produced to enable the design and testing of distributed fuzzy load control algorithms. The load controllers were tested throughout the development process on four autonomous renewable energy systems: - A single phase 25kVA run of river micro-hydro system in Scotland - A wind only system in the UK, with a 60kW stall regulated wind turbine fitted with a synchronous generator - A 30kW micro-hydro system on the island of Rum in Scotland - A 93kW wind-diesel system at the Rutherford Appleton Laboratories in the UK which used a 45kW stall regulated wind turbine fitted with an induction generator. The site results were promising and showed that distributed intelligent load control is an effective technique for controlling autonomous renewable energy systems.

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Cvetkovic, Igor. "Modeling, Analysis and Design of Renewable Energy Nanogrid Systems." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/34994.

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The thesis addresses electronic power distribution systems for the residential applications. Presented are both, renewable energy ac-nanogrid system along with the vehicle-to-grid technology implementation, and envisioned structure and operation of dc-nanogrid addressing all system components chosen as an inherent part of the future electrical architecture. The large-scale model is built and tested in the laboratory environment covering a few operational modes of the ac-nanogrid, while later in the thesis is shown how dc bus signaling technique could be contemplated for the energy management of the renewable energy sources and their maximal utilization. Thesis however puts more focus on the dc-nanogrid system to explore its benefits and advantages for the electrical systems of the future homes that can easily impact not only residential, but also microgrid, grid and intergrid levels. Thus, presented is low frequency terminal behavioral modeling of the system components in dc-nanogrid motivated by the fact that system engineers working on the system-level design rarely have access to all the information required to model converters and system components, other than specification and data given in the datasheets. Using terminal behavioral modeling, converters are measured on-line and their low frequency dynamics is identified by the means of the four transfer functions characteristically used in two port network models. This approach could significantly improve system-level design and simulations. In addition to previously mentioned, thesis addresses terminal behavioral modeling of dc-dc converters with non-linear static behavior showing hybrid behavioral models based on the Hammerstein approach.
Master of Science

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Mueller, Joshua M. (Joshua Michael) 1982. "Increasing renewable energy system value through storage." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98540.

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Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2015.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 135-143).
Intermittent renewable energy sources do not always provide power at times of greatest electricity demand or highest prices. To do so reliably, energy storage is likely required. However, no single energy storage technology is dominant when comparing cost intensities of the energy capacity and power capacity of storage. Past research on energy storage technologies has debated the value of storage technologies for different applications, and has compared the cost structures of different storage technologies without finding generalizable results across both locations and technologies. Here, a single performance metric, the benefit / cost ratio (X) of storage value added is analyzed across six locations globally to show that the relative value of storage technologies is largely location invariant. Electricity price dynamics, specifically the frequency and height of price spikes determine the value of storage, while the duration of price spikes determines the relative value of one technology versus another. We find that cost targets can be set for different technologies with ranging energy and power costs of storage.
by Joshua Michael Mueller.
S.M. in Technology and Policy

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Fleming, Conor F. "Tidal turbine performance in the offshore environment." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:f51fd313-1589-4e9c-98cc-ae6e64c1184b.

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A three dimensional computational model of a full scale axial flow tidal turbine has been used to investigate the effects of a range of realistic environmental conditions on turbine performance. The model, which is based on the Reynolds averaged Navier-Stokes equations, has been developed using the commercial flow solver ANSYS Fluent. A 1:30 scale tidal turbine is simulated in an open channel for comparison to existing experimental data. The rotor blades are directly resolved using a body-fitted, unstructured computational grid. Rotor motion is enabled through a sliding mesh interface between the rotor and the channel boundaries. Reasonably good agreement in thrust and power is observed. The computed performance curves are offset from the measured performance curves by a small increment in rotor speed. Subsequently, a full scale axial flow turbine is modelled in a variety of conditions representative of tidal channel flows. A parametric study is carried out to investigate the effects of flow shear, confinement and alignment on turbine performance, structural loading, and wake recovery. Mean power and thrust are found to be higher in sheared flow, relative to uniform flow of equivalent volumetric flow rate. Large fluctuations in blade thrust and torque occur in sheared flow as the blade passes through the high velocity freestream flow in the upper portion of the profile and the lower velocity flow near the channel bed. A stronger shear layer is formed around the upper portion of the wake in sheared flow, leading to enhanced wake mixing. Mean power and thrust are reduced when the turbine is simulated at a lower position in a sheared velocity profile. However, fluctuations in blade loading are increased due to the higher velocity gradient. The opposite effects are observed when the turbine operates at greater heights in sheared flow. Flow misalignment has a negative impact on mean rotor thrust and power, as well as on unsteady blade loading. Although the range of unsteady loading is not increased significantly, additional perturbations are introduced due to interactions between the blade and the nacelle. A deforming surface is introduced using the volume-of-fluid method. Linear wave theory is combined with the existing free surface model to develop an unsteady inflow boundary condition prescribing combined sheared flow and free surface waves. The relative effects of the sheared profile and wave-induced velocities on turbine loading are identified through frequency analysis. Rotor and blade load fluctuations are found to increase with wave height and wave length. In a separate study, the performance of bi-directional ducted tidal turbines is investigated through a parametric study of a range of duct profiles. A two dimensional axi-symmetric computational model is developed to compare the ducted geometries with an unducted device under consistent blockage conditions. The best-performing ducted device achieves a peak power coefficient of approximately 45% of that of the unducted device. Comparisons of streamtube area, velocity and pressure for the flow through the ducted device shows that the duct limits the pressure drop across the rotor and the mass flow through the rotor, resulting in lower device power.

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Wijewardana, Singappuli M. "Mathematical modelling and control of renewable energy systems and battery storage systems." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/24860.

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Intermittent nature of renewable energy sources like the wind and solar energy poses new challenges to harness and supply uninterrupted power for consumer usage. Though, converting energy from these sources to useful forms of energy like electricity seems to be promising, still, significant innovations are needed in design and construction of wind turbines and PV arrays with BS systems. The main focus of this research project is mathematical modelling and control of wind turbines, solar photovoltaic (PV) arrays and battery storage (BS) systems. After careful literature review on renewable energy systems, new developments and existing modelling and controlling methods have been analysed. Wind turbine (WT) generator speed control, turbine blade pitch angle control (pitching), harnessing maximum power from the wind turbines have been investigated and presented in detail. Mathematical modelling of PV arrays and how to extract maximum power from PV systems have been analysed in detail. Application of model predictive control (MPC) to regulate the output power of the wind turbine and generator speed control with variable wind speeds have been proposed by formulating a linear model from a nonlinear mathematical model of a WT. Battery chemistry and nonlinear behaviour of battery parameters have been analysed to present a new equivalent electrical circuit model. Converting the captured solar energy into useful forms, and storing it for future use when the Sun itself is obscured is implemented by using battery storage systems presenting a new simulation model. Temperature effect on battery cells and dynamic battery pack modelling have been described with an accurate state of charge estimation method. The concise description on power converters is also addressed with special reference to state-space models. Bi-directional AC/DC converter, which could work in either rectifier or inverter modes is described with a cost effective proportional integral derivative (PID/State-feedback) controller.

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Martinez-Cesena, Eduardo Alejandro. "Real options theory applied to renewable energy generation projects planning." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/real-options-theory-applied-to-renewable-energy-generation-projects-planning(280f3df5-f1be-4999-bd33-3931ce3cdbbd).html.

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The existing environmental threats and the ever increasing global dependence on electric power highlight the importance of producing power in a sustainable manner. In accordance, it is vital to attract investments in electricity generation projects based on renewable energy sources, also called renewable energy projects (REP). This poses a challenge, as REP tend to be less financially competitive than their fossil fuel based counterparts. Moreover, the power grid has to be upgraded to integrate large amounts of RESs in an efficient and economic manner. An appealing alternative to enhance the financial appealing of REP is to improve the techniques used for their assessment. These tools produce robust and economically sound assessments, but tend to undervalue REP and other projects under uncertainty, as they neglect the flexibility of the projects to be adjusted in response to uncertainty. This can be corrected by extending the tools with the aid of real options (RO) theory. RO theory can be used to extend assessment techniques to value flexibility derived from the projects, their management, and even their environment, which can be used to enhance the financial value of REP in the changing power sector. In addition, the scope of RO theory is increasing to address flexibility in the design of the projects. Therefore, the theory can drive investments in REP and motivate the design of more profitable projects. This research project seeks to analyse the potential of RO theory to increase the financial worth of different types of REP in the current and changing power sector. The novelties of this research are that it expands RO theory by addressing the flexibility within the design of the projects, the potential of RO theory to manage uncertainties that are exclusive to the projects or typical in the power sector, and other relevant areas of research interest. The research produced several RO methodologies to model the planning, operation, and design of hydropower projects, wind power projects, and solar photovoltaic projects in existing power sector environments and environments characterised by high penetration of RESs and consumers with demand response capabilities. The results demonstrate the applicability of RO theory to enhance the financial value of different types of REP under a wide range of circumstances.

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Chohan, Ghulam Yasin. "Statistical energy analysis of nonconservative dynamical systems." Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239507.

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Cockerill, Timothy Thomas. "Cost modelling of offshore wind energy systems in northern Europe." Thesis, University of Sunderland, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420744.

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Thorburn, Karin. "Electric Energy Conversion Systems : Wave Energy and Hydropower." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7081.

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kollappillai, Murugan Sai Varun. "Analysis of Hybrid Offshore Floating Wind and Marine Power." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-36861.

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Wind energy is a major part of renewable energy production. With fossil fuel depletion and climate change at the cusp, it is an absolute need to implement or evolve the current source or utilization of renewable energy. The wind has been dominating the onshore for many decades and offshore wind turbines are available at shallow depths. To extract more wind energy source deep sea location is recommended. Also, in deep seas, ocean current energy is utilized very sparsely compared to the dominating wind and solar energy. So far no hybrid offshore horizontal axis and ocean current system are in existence. Based on the depth of the sea water the offshore floating structure is classified. Usually, for any floating structure stability is an apprehension. In an offshore floating structure, the damping with respect to the thrust force exerted on the wind turbine will affect the life of the wind turbine. During high wind speed, the angle of inclination would go up to about 4 degrees. The time required for the floating structure to come to rest may also be high. We present an analysis based on an existing floating structure which is a ballast stabilized the floating structure. In this paper, we add an additional submerged turbine and do a 2D analysis on the floating structure to find out whether the structure’s oscillation is well damped or not. We also discuss whether the weight of the submerged will influence the stability or by changing the radius of blades of the submerged turbine will affect the damping.

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Robb, David MacKenzie. "Model based predictive control with application to renewable energy systems." Thesis, University of Strathclyde, 2000. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=20379.

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In the promotion and development of renewable energy systems, control engineering is one area which can directly affect the overall system performance and economics and thus help to make renewable energies more attractive and popular. For cost effectiveness, ideally the renewable energy industry requires a control design technique which is very effective yet simple with methods that are transparent enough to allow implementation by non-control engineers. The objective of this thesis is to determine if Model Based Predictive Control (MBPC) is a suitable control technique for use by the renewable energy industry. MBPC is chosen as it uses simple and fairly transparent methods yet claims to be powerful and can deal with issues, such as non linearities and controller constraints, which are important in renewable energy systems. MBPC is applied to a solar power parabolic trough system and a variable speed wind turbine to enable the general applicability of MBPC to renewable energy systems to be tested and the possible benefits to the industry to be assessed. Also by applying the MBPC technique to these two strongly contrasting systems much experience is gained about the MBPC technique itself, and its strengths and weaknesses and ease of application are assessed. The investigation into the performance of Model Based Predictive Control and in particular its application in the renewable energy industry leads to two contrasting conclusions. For simple systems with non-demanding dynamics and having a good model of the system, MBPC provides a very good and effective solution. However for more demanding systems with complex dynamics and strong non-linearities, a basic MBPC controller, applied by a non-control engineer, cannot be recommended.

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Pitcher, Keith Francis. "Development of biomass renewable energy policies, schemes, systems and procedures." Thesis, University of Leeds, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364895.

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Short, Timothy David. "Induced flow water pumping for stand-alone renewable energy systems." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314323.

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Pietruschka, Dirk. "Model based control optimisation of renewable energy based HVAC Systems." Thesis, De Montfort University, 2010. http://hdl.handle.net/2086/4022.

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During the last 10 years solar cooling systems attracted more and more interest not only in the research area but also on a private and commercial level. Several demonstration plants have been installed in different European countries and first companies started to commercialise also small scale absorption cooling machines. However, not all of the installed systems operate efficiently and some are, from the primary energy point of view, even worse than conventional systems with a compression chiller. The main reason for this is a poor system design combined with suboptimal control. Often several non optimised components, each separately controlled, are put together to form a ‘cooling system’. To overcome these drawbacks several attempts are made within IEA task 38 (International Energy Agency Solar Heating and Cooling Programme) to improve the system design through optimised design guidelines which are supported by simulation based design tools. Furthermore, guidelines for an optimised control of different systems are developed. In parallel several companies like the SolarNext AG in Rimsting, Germany started the development of solar cooling kits with optimised components and optimised system controllers. To support this process the following contributions are made within the present work: - For the design and dimensioning of solar driven absorption cooling systems a detailed and structured simulation based analysis highlights the main influencing factors on the required solar system size to reach a defined solar fraction on the overall heating energy demand of the chiller. These results offer useful guidelines for an energy and cost efficient system design. - Detailed system simulations of an installed solar cooling system focus on the influence of the system configuration, control strategy and system component control on the overall primary energy efficiency. From the results found a detailed set of clear recommendations for highly energy efficient system configurations and control of solar driven absorption cooling systems is provided. - For optimised control of open desiccant evaporative cooling systems (DEC) an innovative model based system controller is developed and presented. This controller consists of an electricity optimised sequence controller which is assisted by a primary energy optimisation tool. The optimisation tool is based on simplified simulation models and is intended to be operated as an online tool which evaluates continuously the optimum operation mode of the DEC system to ensure high primary energy efficiency of the system. Tests of the controller in the simulation environment showed that compared to a system with energy optimised standard control the innovative model based system controller can further improve the primary energy efficiency by 19 %.

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Apelfröjd, Senad. "Grid Connection of Permanent Magnet Generator Based Renewable Energy Systems." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-304659.

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Renewable energy is harnessed from continuously replenishing natural processes. Some commonly known are sunlight, water, wind, tides, geothermal heat and various forms of biomass. The focus on renewable energy has over the past few decades intensified greatly. This thesis contributes to the research on developing renewable energy technologies, within the wind power, wave power and marine current power projects at the division of Electricity, Uppsala University. In this thesis grid connection of permanent magnet generator based renewable energy sources is evaluated. A tap transformer based grid connection system has been constructed and experimentally evaluated for a vertical axis wind turbine. Full range variable speed operation of the turbine is enabled by using the different step-up ratios of a tap transformer. This removes the need for a DC/DC step or an active rectifier on the generator side of the full frequency converter and thereby reduces system complexity. Experiments and simulations of the system for variable speed operation are done and efficiency and harmonic content are evaluated. The work presented in the thesis has also contributed to the design, construction and evaluation of a full-scale offshore marine substation for wave power intended to grid connect a farm of wave energy converters. The function of the marine substation has been experimentally tested and the substation is ready for deployment. Results from the system verification are presented. Special focus is on the transformer losses and transformer in-rush currents. A control and grid connection system for a vertical axis marine current energy converter has been designed and constructed. The grid connection is done with a back-to-back 2L-3L system with a three level cascaded H-bridge converter grid side. The system has been tested in the laboratory and is ready to be installed at the experimental site. Results from the laboratory testing of the system are presented.
Wind Power
Wave Power
Marine Currnet Power

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Coppez, Gabrielle. "Optimal sizing of hybrid renewable energy systems for rural electrification." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/10274.

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Includes bibliograhical references.
This project has the objective of creating a tool for feasibility assessment and recommendations of sizing of hybrid renewable energy systems in rural areas in South Africa. This involves the development of a tool which would analyse information input about the climate of the area and the load demand.

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Gurpinar, Emre. "Wide-bandgap semiconductor based power converters for renewable energy systems." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/40742/.

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The demand for low carbon economy and limited fossil resources for energy generation drives the research on renewable energy sources and the key technology for utilisation of renewable energy sources: power electronics. Innovative inverter topologies and emerging WBG semiconductor based devices at 600 V blocking class are the enabling technologies for more efficient, reliable and accessible photovoltaic based electricity generation. This thesis is concerned with the impact of WBG semiconductor based power devices on residential scale PV inverter topologies in terms of efficiency, volume reduction and reliability. The static and dynamic characterisation of the Si and WBG based devices are carried out, gate drive requirements are assessed and experimental performance comparison in a single phase inverter is discussed under wide range of operating conditions. The optimisation of GaN HEMT based single phase inverter is conducted in terms of converter efficiency, switching frequency and converter volume. The long term mission-profile based analysis of GaN and Si based devices is conducted and impact of WBG devices under low and high switching frequency conditions in terms of power loss and thermal loading are presented. Finally, a novel five-level hybrid inverter topology based on WBG devices is proposed, simulated and experimentally verified for higher power applications.

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Dissertations / Theses on the topic 'Offshore renewable energy systems'

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