This thesis is concerned with the material processing, photophysical and third-order nonlinear optical responses, and applications of a set of conjugated polymers in the telecommunication regions. Polyacetylene-based third-order nonlinear optical materials were chosen as candidates for all-optical signal and image processing. Substituted polyacetylenes were obtained using ring-opening metathesis polymerization of mono-substituted cyclooctatetraenes. Polymerization and processing conditions have been developed to generate thick, large-area films possessing large third-order nonlinearities in the telecommunication bands. The good optical quality of a 200 μm thick substituted polyacetylene film allowed for image correlation via off-resonant degenerated four-wave mixing with improved diffraction efficiency. Poly(2-methoxy-5-(2-ethyl-hexyloxy)-(phenylene vinylene)) (MEH-PPV) and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) composites showed strong nonlinear absorption and potential as optical limiters in the region of 700-900 nm. High optical quality, thick film of MEH-PPV:PCBM with the plasticizer dioctylphthalate (DOP) were made. Optical limiting of femtosecond and nanosecond pulses in the near infrared on these composites showed strong power suppression over a broad temporal regime. Femtosecond and nanosecond transient studies on the same thick MEH-PPV:PCBM:DOP composite films and the experimental results showed evidence for the photogeneration of radical ions as being responsible for the enhanced nonlinear absorption and strong optical suppression in the near infrared. Dithienopyrrole-based donor-acceptor copolymers with narrow bandgap showed strong nonlinear absorption and potential as optical limiters in the telecommunication wavelengths. Molecular engineering was applied to manipulate the spectral overlap of two-photon absorption and subsequent nonlinear absorptions. Femtosecond transient spectroscopy showed near infrared transient absorption and 22 - 61% yields of photogenerated charge-transfer species depending on donor-acceptor coupling strength. Torsional fluctuations of the backbone structure potentially affected the excited state behavior. Evidence suggests that ultrafast relaxation occurs to ground state and to long-lived charge-transfer state from the initially excited state. The dispersion of nonlinear absorption measured using the Z-scan method revealed large two-photon absorption cross sections of these polymers in the telecommunication region. Large suppression of nanosecond pulses at 1064 nm was achieved.

A new Markov chain based energy storage model to evaluate the power supply availability of microgrids with renewable energy generation for critical loads is proposed. Since critical loads require above-average availability to ensure reliable operation during extreme events, e.g., natural disasters, using renewable energy generation has been considered to diversify sources. However, the low availability and high variability of renewable energy sources bring a challenge in achieving the required availability for critical loads. Hence, adding energy storage systems to renewable energy generation becomes vital for ensuring the generation of enough power during natural disasters. Although adding energy storage systems would instantaneously increase power supply availability, there is another critical aspect that should be carefully considered; energy storage sizing to meet certain availability must be taken into account in order to avoid oversizing or undersizing capacity, which are two undesirable conditions leading to inadequate availability or increased system cost, respectively. This dissertation proposes to develop a power supply availability framework for renewable energy generation in a given location and to suggest the optimal size of energy storage for the required availability to power critical loads. In particular, a new Markov chain based energy storage model is presented in order to model energy states in energy storage system, which provides an understanding of the nature of charge and discharge rates for energy storage that affect the system's power output. Practical applications of the model are exemplified using electrical vehicles with photovoltaic roofs. Moreover, the minimal cut sets method is used to analyze the effects of microgrid architectures on availability characteristics of the microgrid power supply in the presence of renewable energy sources and energy storage. In addition, design considerations for energy storage power electronics interfaces and a comparison of various energy storage methods are also presented. / text

Electricity generated from photovoltaics (PV) promises to satisfy the world's ever-growing thirst for energy without significant pollution and greenhouse gas emissions. At present, however, PV is several times too expensive to compete economically with conventional sources of electricity delivered via the power grid. To ensure long-term success, must achieve cost parity with electricity generated by conventional sources of electricity. This requires detailed understanding of the relationship between technology and economics as it pertains to PV devices and systems. The research tasks of this thesis focus on developing and using four types of models in concert to develop a complete picture of how solar cell technology and design choices affect the quantity and cost of energy produced by PV systems. It is shown in this thesis that high-efficiency solar cells can leverage balance-of-systems (BOS) costs to gain an economic advantage over solar cells with low efficiencies. This advantage is quantified and dubbed the "efficiency premium." Solar cell device models are linked to models of manufacturing cost and PV system performance to estimate both PV system cost and performance. These, in turn, are linked to a model of levelized electricity cost to estimate the per-kilowatt-hour cost of electricity produced by the PV system. A numerical PV module manufacturing cost model is developed to facilitate this analysis. The models and methods developed in this thesis are used to propose a roadmap to high-efficiency multicrystalline silicon PV modules that achieve cost parity with electricity from the grid. The impact of PV system failures on the cost of electricity is also investigated; from this, a methodology is proposed for improving the reliability of PV inverters.

The manufacture of photovoltaic (PV) system components has a role to play in the industrialisation and poverty reduction strategies of developing countries. It has also been suggested that small scale local manufacture of balance of systems components has the potential to improve the maintenance, installation and use of the technology. However, PV is a complex technology and most developing countries have not been able to build the capabilities required to manufacture PV system components of an appropriate quality and price, either in the modern or small scale sectors. The factors that determine the success of PV manufacturers in developing countries are therefore of interest. Previous studies on learning in the PV industry have been focused on industry-wide concerns and have not explicitly addressed enterprise-level capability building or challenges specific to developing countries. In particular, there has been very little published about small scale PV manufacture. This thesis therefore aims to improve understanding of the factors that influence capability building, with a view to assisting decision making in relation to PV manufacture in developing countries. The aims of the study have been fulfilled by the development and assessment of a software simulation training tool for PV cell production line engineers, the development of an analysis framework, and application of it to several case study PV enterprises. Through the application of the framework to the case studies, it has been possible to assess the role of software simulations, the suitability of countries with different types of infrastructure for hosting PV manufacturing and the institutional arrangements or interventions that could be used to promote capability building for PV manufacturers in developing countries. While further case studies are required to make more than tentative conclusions, the framework developed and tested in this thesis may now be used as a tool to systematically and rapidly analyse the appropriateness of different types of PV manufacture in particular countries, to identify the weaknesses in their PV technological systems and therefore to suggest where resources should be invested and where appropriate institutional changes could be made. The simulation software has been demonstrated to be an effective capability building tool, thus providing one of the key elements required for successful manufacturing.

The manufacture of photovoltaic (PV) system components has a role to play in the industrialisation and poverty reduction strategies of developing countries. It has also been suggested that small scale local manufacture of balance of systems components has the potential to improve the maintenance, installation and use of the technology. However, PV is a complex technology and most developing countries have not been able to build the capabilities required to manufacture PV system components of an appropriate quality and price, either in the modern or small scale sectors. The factors that determine the success of PV manufacturers in developing countries are therefore of interest. Previous studies on learning in the PV industry have been focused on industry-wide concerns and have not explicitly addressed enterprise-level capability building or challenges specific to developing countries. In particular, there has been very little published about small scale PV manufacture. This thesis therefore aims to improve understanding of the factors that influence capability building, with a view to assisting decision making in relation to PV manufacture in developing countries. The aims of the study have been fulfilled by the development and assessment of a software simulation training tool for PV cell production line engineers, the development of an analysis framework, and application of it to several case study PV enterprises. Through the application of the framework to the case studies, it has been possible to assess the role of software simulations, the suitability of countries with different types of infrastructure for hosting PV manufacturing and the institutional arrangements or interventions that could be used to promote capability building for PV manufacturers in developing countries. While further case studies are required to make more than tentative conclusions, the framework developed and tested in this thesis may now be used as a tool to systematically and rapidly analyse the appropriateness of different types of PV manufacture in particular countries, to identify the weaknesses in their PV technological systems and therefore to suggest where resources should be invested and where appropriate institutional changes could be made. The simulation software has been demonstrated to be an effective capability building tool, thus providing one of the key elements required for successful manufacturing.

Fundação Araucária / Esta dissertação de mestrado apresenta o estudo, desenvolvimento e implementação de uma nova estrutura, composta por um conversor CC-CC bidirecional, conectada em paralelo com o sistema, para busca do ponto de máxima potência em painéis solares fotovoltaicos para aplicações isoladas da rede elétrica. Inicialmente são expostos os principais fatores que levaram à escolha do tema, assim como a problemática que motivou essa dissertação. Na seqüência é realizado um estudo sobre energia fotovoltaica, onde são mencionados os principais tipos de células fotovoltaicas e o comportamento de um módulo fotovoltaico em função da variação climática. Também são apresentados nesta dissertação os resultados do estudo, simulações, implementação e comparação entre os algoritmos de busca automática do ponto de máxima potência (MPPT) de módulos fotovoltaicos, baseados no método da Perturbação & Observação (P&O) e no método fuzzy. A seguir são mostrados os detalhes do funcionamento da nova estrutura proposta para busca do ponto de máxima potência (MPPT), onde se utiliza um conversor bidirecional (buck-boost) conectado em paralelo com o sistema, bem como o resultado das simulações da nova estrutura proposta que foram realizadas. Por fim, são apresentados os resultados experimentais dos ensaios realizados em laboratório e do comportamento de um módulo fotovoltaico real conectado à nova estrutura proposta. Os resultados experimentais comprovam a melhoria no rendimento do sistema fotovoltaico quando comparado com as soluções clássicas para a busca do ponto de máxima potência. / This work presents the analysis, design, and implementation of a new parallel connected structure, composed by a parallel bidirectional DC-DC power convert, for maximum power point tracking of stand-alone photovoltaic power generation systems. At first, the main factors that motivated the choice the topic of this work are presented. In sequence, the main types of photovoltaic cells and the photovoltaic panel characteristics in function of the climatic variation are analyzed. The study, implementation, comparison and simulation results of algorithm of maximum power point tracking (MPPT) also are presented in this work. The algorithm of MPPT are based in the method of Perturbation and Observation (P&O) and in the fuzzy method. Following, the characteristics of the new structure proposal, composed by a parallel connection bidirectional DC-DC converter simulations results. Finally, are presented the laboratorial experimental results and the behavior or a real photovoltaic module connected to the new structure proposal.

L’objet de cette thèse est l’intégration des parcs photovoltaïques intelligents au marché de l’électricité dans un environnement de libre concurrence. Les centrales photovoltaïques intelligentes sont celles qu’incluent systèmes de stockage pour réduire sa variabilité et en plus fournir à l’ensemble une plus grande contrôlabilité. Ces objectives techniques sont obtenues grâce à la capacité bidirectionnelle d’échange et stockage d’énergie qu’apportent les systèmes de stockage, dans ce cas, les batteries. Pour obtenir la rentabilité maximale des systèmes de stockage, le dimensionnement doit être optimisé en même temps que la stratégie de gestion avec laquelle le système de stockage est commandé. Dans cette thèse, une fois la technologie de stockage plus adapté à l’application photovoltaïque est sélectionnée, à savoir la technologie de lithium-ion, une participation innovatrice de part des parcs photovoltaïques intelligents dans le marché de l’électricité est proposée qui optimise à la fois le dimensionnement et la stratégie de gestion d’une manière simultanée. Ce processus d'optimisation ainsi que la participation au marché de l'électricité a été appliquée dans un cas d’étude réel, ce qui confirme que cette procédure permet de maximiser la rentabilité économique de ce type de production. / The present PhD deals with the integration of intelligent photovoltaic (IPV) power plants in the electricity markets in an environment subject to free competition. The IPV power plants are those that include energy storage systems to reduce the variability and to provide the entire group a controllability increase. These technical objectives are obtained thanks to the bidirectional exchanging and storing capability that the storage system contributes to, in this case, battery energy storage system (BESS). In order to obtain the maximum profitability of the BESS, the sizing must be optimized together with the control strategy that the BESS will be operated with. In the present PhD, once the most performing battery energy storage technology has been selected, the lithium-ion technology, an innovative IPV power plant electricity market participation process is proposed which optimizes both the sizing and the energy management strategy in the same optimization step. This optimization process together with the electricity market participation has been applied in a real case study, confirming that this procedure permits to maximize the economic profitability of this type of generation.

L’objectif de cette thèse est d’étudier les pertes dans un micro-réseau urbain à courant continu ayant comme but principal l’amélioration de l’efficacité énergétique. Sachant qu’un tel micro-réseau multi-source consiste en plusieurs sources dont les natures sont très différentes, les convertisseurs statiques sont indispensables mais ils apportent des pertes de puissance. Ces pertes sont très variables en particulier avec les sources renouvelables comme les panneaux photovoltaïques. Dans la littérature le rendement du convertisseur est souvent traité comme une constante, mais des tests expérimentaux sont effectués pour prouver que le rendement est variable. Afin d’étudier les pertes en détail, un état de l’art sur les convertisseurs statiques a été effectué pour estimer les pertes en fonction de divers paramètres et variables. En considérant la précision d’estimation et la vitesse de calcul, un modèle énergétique moyen basé sur la fiche technique des composants utilisés est établi. Des tests expérimentaux sont effectués pour valider ce modèle sur les différents convertisseurs DC/DC et DC/AC utilisés dans le micro-réseau. Grâce à la simplicité de ce modèle, il peut s’insérer dans le système du contrôle en temps réel. Par conséquent, des stratégies de pilotage du micro-réseau sont proposées pour prendre en compte le rendement variable dans le contrôle global et local du micro-réseau. Ces stratégies permettent d’avoir un délestage flexible des puissances dans le micro-réseau et d’accélérer la vitesse de convergence du contrôle, avec la connaissance des pertes de chaque convertisseur à chaque instant. Les résultats montrent que ces stratégies conduisent à la réduction du coût énergétique et améliorent légèrement le rendement global du micro-réseau. / The object of the thesis is to study the power losses in an urbain DC microgrid in order to improve the energy efficiency. Noted that such a multi-source microgrid consist of several sources whose nature is different one from another, the static power converters are essential but they brings power losses. The power losses are quite variable in particular with the renewable energy source such as the photovoltaic panels. In the litteral works the converter efficiency is often treated as a constant, but experimental tests are carried out to show its variation. For the sake of study the power loss thoroughly, a state of art of the static converter is studied to develop a simple and fast estimation methode of power losses. Aiming at the tradeoff between the estimation accurancy and the calculation time, an averaged energy model is developped on the basis of the component datasheet. The experimental tests are carried out to validate the application of the model on the DC/DC and DC/AC converters used in the microgrid. Due to its simplicity, the model can be implemented in the real-time system. Thus the energy management strategies are proposed to interact with the variable efficiency on the high and low level control. These strategies are capable of shedding the powers in the microgrid with flexibility and accelerating the the convergency spped of control through the knowledge of power losses of each converter. The results show that the energy cost has decreased and the microgrid global efficiency is slightly improved.

The diploma thesis focuses on the issue of fires of small photovoltaic power plants located on the roofs of buildings. When a photovoltaic power plant is being fired, the photovoltaic system is a very dangerous part of the power generation technology. In this part of the power plant, it is very problematic that the switching off of the electric dc current and the fire-fighters can cause electric shock. In the research part there is description and photodocumentation of the visited photovoltaic power plants, where the tour was carried out with an emphasis on the possible fire of the object. An important part of this chapter is the case studies of PPS fires and electric shocks. In addition, an overview of several fire interventions already carried out on the photovoltaic power plant located on the roof of the building. Finally, the author identified weaknesses for effective and safe intervention and processed the firefighting documentation for the PPSs visited. The discussion contains an indication of the identified shortcomings in the methodological sheets of the Combat Order of Fire Protection Units. The author outlines the possible risks for intervening firefighters at the PPSs visited and compares the elimination of these risks in the processing of firefighting documentation. Also mentions photovoltaic power plants in floodplains and points to potential hazards when flooding the PPS. Finally, a proposal is made to modify the Combat Order of Fire Protection Units and measures to ensure greater security of firefighters during fires of photovoltaic power plants.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The search for diversity of energy sources in the world is one of the challenges that are driving research to fill this demand with alternative energy sources. So we have the need to explore alternative and renewable resources that bring flexibility and sustainability in its use. Presented before the panorama, the generation of electricity with solar photovoltaic systems is a trend, and has its technology constantly advancing, presenting itself as an immediate solution to this pursuit of diversity. The energy extracted from the Sun in photovoltaic generation systems depends on the flow of energy from the solar radiation in a plane perpendicular to the rays. Therefore, the average solar energy obtained by conventional solar panels during the course of the day, is not always maximized. One reason is that the fixed panels are not at an angle of zero degree zenith in relation to the Sun position. Thus, the movement East (E) to the West (W) daily, with the Earth's seasonal, directly affects the radiation intensity received by the photovoltaic panels. In this context, solar trackers can be used as devices that improve substantially the efficiency of photovoltaic panels, by letting them always perpendicular to the incident radiation received from the sun. In this dissertation demonstrates a methodology for automated solar tracking two axes for photovoltaic panels. The qualitative and quantitative results presented here show the real gain in power generation through the development of a real-time control algorithm for solar tracking systems of two axes, with their simulations and testing a low-cost prototype, developed in laboratory Center of Excellence in Energy and Power Systems (CEESP). Moreover, the results show that this methodology adapts successfully to the different conditions of use to track the sun's position, both in the laboratory and in the field. / A busca pela diversidade da matriz energética no mundo é um dos desafios que estão impulsionando pesquisas para preencher essa demanda com fontes de energia alternativa. Assim temos à necessidade de explorar recursos alternativos e renováveis que tragam flexibilidade e sustentabilidade quanto à sua utilização. Diante do panorama apresentado, a geração de energia elétrica com sistemas fotovoltaicos solares é uma tendência, e tem sua tecnologia em constante avanço, apresentando-se como uma solução imediata para essa busca da diversidade. A energia extraída do Sol em sistemas de geração fotovoltaicos depende do fluxo energético proveniente da radiação solar num plano perpendicular aos raios. Por isto, a energia solar média obtida pelos painéis solares convencionais durante o decorrer do dia, nem sempre é maximizada. Uma das causas é que os painéis fixos não estão com um ângulo de zênite de zero grau em relação à posição do Sol. Assim sendo, o movimento Leste (L) à Oeste (O) diário, junto ao sazonal da Terra, afeta diretamente a intensidade de radiação recebida pelos painéis fotovoltaicos. Neste contexto, os rastreadores solares podem ser usados como dispositivos que melhoram substancialmente à eficiência dos painéis fotovoltaicos, por deixálos sempre numa posição perpendicular à radiação incidente recebida do Sol. Nesta dissertação demonstra-se uma metodologia para rastreamento solar automatizado de dois eixos para painéis fotovoltaicos. Os resultados qualitativos e quantitativos aqui apresentados evidenciam o real ganho na geração de energia por meio do desenvolvimento de um algoritmo de controle em tempo real para sistemas de rastreamento solar de dois eixos, com as respectivas simulações e testes num protótipo de baixo custo, desenvolvido no laboratório do Centro de Excelência em Energia e Sistemas de Potência (CEESP). Além disso, os resultados evidenciam que esta metodologia se adapta com êxito às diferentes condições de uso para rastrear posições do sol, tanto em laboratório como no campo.