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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

[en] JOINT STOCHASTIC SIMULATION OF RENEWABLE ENERGIES / [pt] SIMULAÇÃO ESTOCÁSTICA CONJUNTA DE ENERGIAS RENOVÁVEIS

GUSTAVO DE ANDRADE MELO 27 September 2022 (has links)
[pt] O aumento da participação de fontes de energias renováveis variáveis (ERVs) na matriz elétrica do Brasil traz diversos desafios ao planejamento e à operação do Sistema Elétrico Brasileiro (SEB), devido à estocasticidade das ERVs. Tais desafios envolvem a modelagem e simulação dos processos intermitentes de geração e, dessa forma, um volume considerável de pesquisas tem sido direcionado ao tema. Nesse contexto, um tópico de crescente importância na literatura relaciona-se ao desenvolvimento de metodologias para simulação estocástica conjunta de recursos intermitentes com características complementares, como, por exemplo, as fontes eólica e solar. Visando contribuir com essa temática, este trabalho propõe melhorias a um modelo de simulação já estabelecido na literatura, avaliando sua aplicabilidade a partir de dados do Nordeste brasileiro. A metodologia proposta baseia-se em discretização das séries temporais de energia aplicando a técnica de machine learning k-means, construção de matrizes de transição de estados com base nos clusters identificados e simulação de Monte Carlo para obtenção dos cenários. As séries sintéticas obtidas são comparadas aos resultados gerados pelo modelo já estabelecido na literatura a partir de técnicas estatísticas. Quanto ao alcance dos objetivos da pesquisa, a modelagem proposta se mostrou mais eficiente, gerando cenários que reproduziram satisfatoriamente todas as características dos dados históricos avaliadas. / [en] The increased participation of variable renewable energy sources (VRES) in Brazil s electricity matrix brings several challenges to the planning and operation of the Brazilian Power System (BPS), due to the VRES stochasticity. Such challenges involve the modeling and simulation of intermittent generation processes and, in this context, a considerable amount of research has been directed to the theme. In this context, a topic of increasing importance in the literature is related to the development of methodologies for joint stochastic simulation of intermittent resources with complementary characteristics, such as wind and solar sources. Aiming to contribute to this theme, this work proposes improvements in a simulation model already established in the literature, evaluating its applicability based on Brazilian Northeast data. The proposed methodology is based on the discretization of energy time series applying the kmeans machine learning technique, construction of state transition matrices based on the identified clusters, and Monte Carlo simulation to obtain the scenarios. The synthetic series obtained are compared to the results generated by the model already established in the literature from statistical techniques. Regarding the scope of the research objectives, the proposed modeling demonstrated more promising results, generating scenarios that satisfactorily reproduced all the evaluated characteristics of the historical data.
62

Statistické modely trhu obnovitelných energií / Statisitcal models of the renewable energy market

Kozma, Petr January 2006 (has links)
An efficient application and development of renewable energy sources is one of the most important contribution to the energetic balance of the human society. Anyhow, statistical model of the renewable energy market, which would fundamentally explain relevant economical rules related to these perspective energetic resources, is not clearly known up to now. Nevertheless, the relevant statistical data concerning application of solar energy (photovoltaic and thermo-solar heating) are available for the last twenty years. Based on the economic models, statistical data concerning sales of photovoltaic models and thermo-solar collectors sales have been analysed in this work. It has been shown that the model of constant elasticity predicts an exponential increase which will slow down when a certain level of annual cumulative sales was reached. The model of constant elasticity was found to be successful to interpret past sales data. In the approach of variable elasticity model the parameter of the elasticity has been modified as a function of variables such as market volume, price and time through the statistical evaluation. It enabled to calculate initial, saturation and competitive market conditions, as well. Whereas the constant elasticity demand model describes exponential growth of sales and installations, which was characteristic for the beginning of the application of these renewable resources of energy, the variable elasticity demand model describes a more realistic situation, where cumulative sales either increase or decrease and prices vary subsequently. Simple growth model of unlimited demand based on the growing sales is not realistic and could not be feasible in the long term. The market elasticity could be understood as a real economical parameter representing percentual market increase or decrease at a given time; in the variable demand elasticity model, the constant elasticity is replaced by a function of a market volume, price and time. In this case, we can estimate model parameters for the different market conditions: growth, saturation and decrease. The function representing the capital adequacy in the generalized market model has also been deliberated. Statistical models have been used to determine cumulative sales and market prices of photovoltaic modules and thermo-solar collectors. Moreover, model parameters have been used for the calculation of the realized photovoltaic and thermo solar projects' capital adequacy on the renewable energy market. By using model parameters, renewable energy market forecast up to 2020 has been estimated. We have used generalized market model to credibly estimate future renewable energy market until 2020; as well as extend model parameterization on other resources of renewable energy (water and wind, geothermal sources, biomass) and set prices of energy produced from these renewable sources. Potential energetic savings have been estimated for households (apartments and private houses), who can be relevant consumers of energy from renewable sources. We have performed statistical findings on randomly selected files, where we have reached a real energy consumption, to prove this. This research allowed us to perform a real estimate of a renewable energy contribution to the total energy balance. We have successfully proved that linearly growing capital adequacy function, with an annual growth between 2.5% and 3.0%, is reflecting the renewable energy market sufficiently and is fully in line with an average growth of the total energy consumption. Renewable energy share on the total energy balance will grow substantially to reach a level of 15% in 2015 on the world market and a level of 8% in the Czech Republic for the same period with a perspective to reach a level of 11% in 2020 respectively. Assuming this level of renewable energy on the total production will lead to a decrease of CO2 emissions by three million of tones in 2015 and by four million of tones in 2020. Final reach of this status quo is fully predicted by our statistical model for renewable energy market.
63

Operação flexível de conversores trifásicos conectados à rede elétrica / Strategy for flexible operation of three-phase converters connected on Grid-tie

Luz, Alessandro Lucindo da 13 November 2017 (has links)
Submitted by ALESSANDRO LUCINDO DA LUZ null (aledaluz@hotmail.com) on 2018-01-10T01:24:32Z No. of bitstreams: 1 Operacao flexivel conversores_ALuz.pdf: 10997918 bytes, checksum: 18fe1f6d3eba73d11bf63fab8cf0a0be (MD5) / Approved for entry into archive by Maria Marlene Zaniboni null (zaniboni@bauru.unesp.br) on 2018-01-10T11:41:48Z (GMT) No. of bitstreams: 1 luz_al_me_bauru.pdf: 10997918 bytes, checksum: 18fe1f6d3eba73d11bf63fab8cf0a0be (MD5) / Made available in DSpace on 2018-01-10T11:41:48Z (GMT). No. of bitstreams: 1 luz_al_me_bauru.pdf: 10997918 bytes, checksum: 18fe1f6d3eba73d11bf63fab8cf0a0be (MD5) Previous issue date: 2017-11-13 / Este trabalho de mestrado descreve uma estratégia de operação multifuncional e flexível aplicado a conversores trifásicos CC-CA (inversores) conectados à rede de distribuição de energia elétrica. A estratégia proposta é capaz de injetar potência ativa na rede e compensar correntes de distúrbios (reativos, desbalanço e harmônicos) simultaneamente. O maior objetivo desta operação flexível é de melhorar a Qualidade de Energia Elétrica em um ponto de acoplamento comum (PAC) permitindo a compensação total ou parcial destes distúrbios ou fatores que degradam a Qualidade de Energia Elétrica. O fator de potência é o principal fator de qualidade a ser observado e ele é calculado através da Teoria da Potência Conservativa – CPT. Entretanto, com base no fator de potência medido pelo lado da rede de distribuição e o fator de potência desejado, um coeficiente de compensação – k é calculado para o ajuste das correntes de compensação dos distúrbios que geram a potência não ativa. / This paper depicts a multifunctional and flexible control strategy applied in three-phase inverters, which are connected to the distribution network. The proposed strategy is able to inject active power into the electrical grid and compensate current disturbances (reactive, harmonics and unbalance) simultaneously. The main goal of this flexible strategy is to improve the Power Quality at the point of common coupling (PCC) allowing full or partial compensation of disturbances. Power factor is the main quality index observed and it is calculated according to Conservative Power Theory - CPT. Therefore, based on the power factor measured in the grid side and the desired value for the power factor, a compensation coefficient - k is calculated continuously adjusting the amplitude of the compensation current.
64

[en] TRANSMISSION EXPANSION PLANNING CONSIDERING THE INTERMITTENCY OF WIND GENERATION / [pt] PLANEJAMENTO DA EXPANSÃO DA TRANSMISSÃO CONSIDERANDO A INTERMITÊNCIA DA GERAÇÃO EÓLICA

JERSON ERASMO LEON ALMEIDA 23 January 2018 (has links)
[pt] O planejamento da expansão da transmissão (PET) visa identificar os novos reforços a serem implementados na rede do sistema elétrico de potência, necessá-rios para assegurar uma adequada interligação entre a demanda e a geração do sistema, ambas previstas para o horizonte de planejamento. Um bom plano de expansão deve garantir o equilíbrio entre os custos de investimento e operação, mantendo um nível satisfatório de continuidade no fornecimento de energia. En-tretanto, a identificação de boas soluções para o PET tem se tornado uma tarefa cada vez mais difícil. Isso se deve, principalmente, às características e dimensões dos sistemas atuais, incluindo o aumento na dependência de fontes renováveis, e à não linearidade e natureza combinatória do problema de otimização. Nesta dissertação é proposta uma nova metodologia para resolver o proble-ma PET com alta penetração de energia renovável, em particular a eólica. A me-todologia é baseada na aplicação de uma nova ferramenta de otimização para so-lução do PET estático, a qual é classificada como metaheurística construtiva, onde soluções viáveis de boa qualidade são paralelamente construídas a partir da topo-logia inicial, por meio de adições graduais de reforços mais atrativos para a rede. Outras heurísticas são também utilizadas. Ênfase é dada à modelagem de cenários de geração eólica, que representam a energia renovável da rede a ser planejada, a qual deverá permitir uma operação flexível e adaptada à intermitência destas fon-tes. São utilizados o critério de segurança N-1 e o modelo linear DC de rede, com a consideração de perdas ôhmicas. Uma variante do sistema IEEE RTS, com inserção de fontes eólicas, é utilizada para testar a metodologia proposta. / [en] Transmission expansion planning (TEP) aims to identify the new reinforce-ments to be installed in the electric power system, necessary to ensure an adequate interconnection between demand and generation of the system, both foreseen for the planning horizon. A good expansion plan should ensure a balance between investment and operating costs, while maintaining a satisfactory level of continui-ty in the energy supply. However, identifying good expansion solutions for TEP has become an increasingly difficult task. This is mainly due to the characteristics and dimensions of the current systems, including the increase in the dependence of renewable sources, and the nonlinearity and combinatorial nature of the optimi-zation problem. In this dissertation, a new methodology is proposed to solve the TEP prob-lem with high penetration of renewable energy, in particular wind power. The methodology is based on the application of a new optimization tool for static TEP solution, which is classified as a constructive metaheuristic, where feasible solu-tions of good quality are simultaneously constructed from the initial topology of the network, through incremental additions of reinforcements more attractive to the grid. Other heuristics are also used. Emphasis is given to the modeling of wind power scenarios, which represent the renewable energy of the network to be planned, which should allow a flexible operation and adapted to the intermittency of these sources. The security criterion N-1 and the linear DC network model are used, with the consideration of ohmic losses. A variant of the IEEE RTS sys-tem, with insertion of wind sources, is used to test the proposed methodology.
65

Contribution au dimensionnement et à l'optimisation des systèmes hybrides éoliens-photovoltaïques avec batteries pour l'habitat résidentiel autonome / Contribution to the sizing and to the optimization of the wind-photovoltaic hybrid systems with batteries for the autonomous residential housing environment

Abbes, Dhaker 20 June 2012 (has links)
Cette thèse est une contribution à l'étude des systèmes hybrides éoliens-photovoltaïques avec batteries sur plusieurs aspects : évaluation des sources, modélisation, simulation, optimisation du dimensionnement et enfin commande et supervision. Ainsi, dans un premier temps, une étude d'impact sur l'évaluation du potentiel en énergies renouvelables sur un site donné en prenant en compte la consommation dans un habitat résidentiel (période et méthode d'acquisition des données, techniques d'évaluation, ...) est présentée. Puis, les modèles énergétiques des différents composants du système ainsi que les aspects économiques et écologiques sont définis. L'ensemble est représenté à l'aide du logiciel Matlab/Simulink. Ensuite, une méthodologie d'optimisation du dimensionnement du système multi-sources est développée et comparée à plusieurs approches, allant d'une optimisation mono-objective à une multi-objective et évaluant le coût économique et écologique de chacune de ces solutions. Une solution « pratique » est retenue pour les composants PV, éolien et batteries du système final afin d'en évaluer la viabilité énergétique, économique et écologique. Les résultats montrent un impact environnemental faible et un coût raisonnable du point de vue économique ainsi qu'une satisfaction de la charge dans les limites tolérées par l'usager. La méthode développée de dimensionnement est comparée à un outil commercial existant. Enfin, un banc expérimental PV-éolien avec batteries est mis en oeuvre avec une nouvelle technique de supervision basée sur le contrôle des courants et l'estimation de l'état de charge des batteries. / This thesis is a contribution to the study of photovoltaic-wind-battery hybrid systems for several aspects: source evaluation, modeling and simulation, design optimization and finally control and supervision. Thus, an impact study on the evaluation of renewable energy potential at a given site taking into account consumption in residential housing (period and method of data acquisition, evaluation techniques...) is presented. In addition, all the components of the system are modeled and economic and ecological aspects are defined in order to make an overall assessment of various system configurations. All models are represented using Matlab/Simulink tool. Then, a methodology for single and multi-objective design optimization of a multi-source system is developed to minimize system Life Cycle Cost (LCC), Embodied Energy (EE) and Loss of Power Supply Probability (LPSP). A "practice solution" is thus retained and evaluated. Results show a low environmental impact and a reasonable economic cost as well as a satisfaction of the load within the limits tolerated by the user. Besides, a very convincing comparison of the developed sizing method to an existing commercial tool is presented. At the end, an experimental PV-wind-battery tested is developed in laboratory to ensure a quasi-realistic emulation of hybrid system behavior for different configurations. Accordingly, a new supervision strategy based on currents control and battery state of charge estimation is successfully validated.
66

Přehled a analýza komunitárního a tuzemského práva v oblasti obnovitelných zdrojů energie / Summary and analysis of the acquis communautaire and the domestic law in the area of renewable energy sources

Divoký, Zdeněk January 2011 (has links)
The goal of this diploma's thesis is to analyze legal regulation of renewable energy sources in a context of environmental and energy law, up to the scale of subordinate legislation. The work presents summary analysis of the past and present developments in the energy law in connection to the actual problems in this field. This work gives comprehensive overlook of the legal regulation including legal regulation of the subsidies and usage of the renewable sources of energy. The overlook of recent history describes the original regulation by law regulation, as well as changes in the legal regulation connected to the changing cost of renewable energy. The first chapter gives the definition of terms, the second chapter is about European law in the area of the renewable energy sources. The third chapter focuses on the domestic legal regulation of Czech Republic. The fourth chapter brings analysis of renewable energy sources concerning other Community policies like energy security and environmental law and the fifth chapter looks into present tendency in the legislation sphere in context with present issues.
67

Návrh a realizace mobilní fotovoltaické elektrárny / Design and Realization of Mobile Photovoltaic Power Station

Lednický, Ján January 2017 (has links)
This diploma thesis entitled Design and realization of a mobile photovoltaic power plant is dividet into two parts. In the first, theoretical part one can learn about the state of representation of renewable energy sources in the field of electrical power engineering and about the structure of photovoltaic power station systems. The secont part of this thesis is focused on the own design and realization of the mobile photovoltaic power plant, on the selection of individual suitable components and ther dimensioning. In addition, a model of a mobile power plant has been created, on the basis of which the power plant was constructed. Finally, one can find a source code analysis of a power plant monitoring using a microcontroler
68

Modelování a simulace hybridní mikro sítě v prostředí PSCAD / Modeling and simulation of a hybrid micro grid in PSCAD environment

Moravčík, Martin January 2012 (has links)
In the opening part of this master´s thesis there is given concept, description, usage and advantages of micro hybrid grids in comparison to micro grids and there are evolution steps towards hybrid grid. There is also a mention about economics of operation of these grids. In the second part of this thesis there are descriptions of devices that are suitable for usage in micro hybrid grids with emphasis on generators and accumulation possibilities. In the next part of this thesis there is given an approach and description for modeling of various components of hybrid grids in PSCAD environment. In the next part of this thesis there are given simulation results that were conducted on created model. Especially power balance in 24 hour operation of the grid with method for determining suitable size of accumulation and installed capacity of photovoltaics. And next there are showed responses from change of power from photovoltaics, next there is a transition to islanded mode and last there is showed the behavior of converter when the limits of accumulation are reached. In the final part of this thesis there are conclusions, fulfillment of goals of this thesis and possibilities of further study.
69

Kogenerační jednotky na rostlinný olej / Cogeneration plants on vegetable oil

Macoszek, Pavel January 2013 (has links)
The thesis is focused on cogeneration units on vegetable oil. The first chapter contains basic information about the production, supply and consumption of electric energy in the Czech Republic and about renewable energy sources. The following chapter is devoted to possibilities of use oil kinds of phytomass in the Czech Republic, or products made from them. Next chapter is mentioned on legislation allowing the use of used cooking oils for energy purposes. It contains a summary of the laws and regulations and options regarding subsidies for electric and heat power. The main objective of these chapters is to explain the issue of the establishment and operation of cogeneration units on vegetable oil. The following chapters are devoted to the design and study of simultaneously operated cogeneration unit on the vegetable oil with a combustion engine and the calculation of economic operation running. The reason of study is to evaluation, which on based of the input values and calculation methods determine the economic efficiency of the project cogeneration unit on vegetable oil under mode purchase price and mode green bonus. Appreciation is also given to the overall legal review and responsibilities of cogeneration units on vegetable oil.
70

Optimal sizing and system management of water pumping and desalination process supplied with intermittent renewable sources / Dimensionnement et gestion optimale d’un système autonome dédié au pompage et au dessalement alimenté par des sources renouvelables intermittentes

Nguyen, Duc Trung 28 May 2013 (has links)
Cette étude s’intéresse à la conception systémique intégrant simultanément les questions de dimensionnement et de gestion optimale de l'énergie. Le système étudié concerne un procédé de pompage intégrant un processus de dessalement d’eaux saumâtres alimenté par des sources de puissance hybrides renouvelable incluant un minimum de stockage électrochimique. Ce cas d’étude appartient à une classe typique de systèmes autonomes alimentés par des sources intermittentes dont profil de puissance a une forme "donnée" : « selon les conditions climatiques (ensoleillement, vent), avec un minimum de stockage d’électricité, la puissance offerte doit être convertie ou stockée hydrauliquement sous peine d’être gaspillée ». L'influence des conditions d'environnement et la robustesse du processus d’optimisation est enfin aussi discutée dans cette thèse. Deux types de modèles mathématiques, dynamiques et quasi-statiques, sont mis en œuvre pour décrire l'ensemble du dispositif. Le système est tout d’abord modélisé dynamiquement par Bond Graphs. Pour une simulation plus rapide, plus adaptée à l’optimisation globale du système, un modèle quasi-statique est créé pour être simulé dans l'environnement Matlab. Pour de tels dispositifs, étant donné une certaine puissance offerte au fil du vent et du soleil, trouver le point optimal de fonctionnement à chaque période consiste en un partage de puissance entre les sous systèmes de pompage et de traitement de l’eau : ce processus est plutôt complexe compte tenu des non linéarités (courbes rendement – puissance) et de la présence de nombreuses contraintes relatives aux limitations de puissance des pompes, aux conditions de niveau des réservoirs, ainsi qu’aux limitations de pression et de débit dans les processus hydrauliques (pompes osmoseur). Nous montrerons qu’il n’est pas si trivial de choisir une fonction objectif qui assure simultanément la performance et la robuste du système vis-à-vis des conditions d’environnement : une fonction objectif robuste quel que soit le profil de puissance des sources est ainsi proposée pour mettre en œuvre une gestion optimale de l’énergie. Le problème d’optimisation étant posé sous forme standard, consistant en la maximisation d’une fonction objectif sous contraintes, des approches d’optimisation efficaces par programmation non linéaire sont employées. La question du dimensionnement et son couplage à la gestion énergétique est finalement étudiée. En particulier, l’intérêt de la modularité des systèmes, considérant plusieurs pompes connectées en parallèle pour la même fonction, est investigué. / This study focuses on systemic design, integrating simultaneously issues of sizing and optimal energy management. The system under study consists of a pumping process including a brackish water desalination system fed by hybrid renewable power sources with minimum electrochemical storage. Such a device belongs to the class of “autonomous systems” supplied by intermittent sources whose power profile has a “given” waveform: “with minimum electrical storage, power has to be converted, stored in water tanks, or wasted following climatic (sun, wind) conditions”. Influence of environment conditions and robustness of the optimization process is then also discussed in this thesis. Both dynamic and quasi static models are implemented for representing the whole system. The device is firstly modeled dynamically by Bond Graph methodology. For faster simulations, which are more suitable for system optimization, a quasi static model is created to be simulated in the Matlab environment. For such systems, given a certain source power, finding optimal operation point at each period consists of a power sharing between all pumping devices: it is a complex process with huge nonlinearities (efficiency vs power curves) and with many constraints as for the limitation of pump powers, tank level conditions, or pressure and flow limitations in hydraulic network and pumping devices. It is not so trivial to define an objective function which ensures system performance and robustness versus environment conditions: a convenient objective function, whatever the input power profile, is then proposed to implement the optimal management. The optimization problem being mathematically expressed, consisting of objective function maximization under constraints, efficient optimization methods by non linear programming are implemented. The issue of sizing and its coupling with system management efficiency is finally studied. In particular, the interest of modular operation with several pumps connected in parallel is also concerned in this research.

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