This study aims to examine and quantify the impact from increasing penetration of electric car chargers and solar cells in Mälarenergi's distribution grids. Four different types of low voltage grids are examined: a small rural grid, an older suburban grid, a modern suburban grid and a modern urban grid with multi-dwelling houses. The networks are modeled in Matpower, a MATLAB Power System Simulation Package with grid and metering data from Mälarenergi's NIS (Network Information System), insolation data from Swedish Meteorological and Hydrological Institute (SMHI) and simulated data from an electrical vehicle Home-charing model based on residential activity patterns. The idea has been to use as few assumptions as possible and as much real measurements as possible. The results show that problems such as unwanted voltage levels at the customer's connection points and increasing power flux in the low voltage substation's is to be expected based on aforementioned increasing penetration. The various low voltage networks are affected to varying degrees due to its different structure and type of customers. Measures to increase acceptance for the above mentioned changes have also been reviewed. Line gain shows best properties to reduce both losses and voltage variations. Reactive power compensation in the solar cell's inverters can reduce voltage increases, but with the disadvantage that network losses increase. The use of smart chargers that can control when the charging of electrical vehicles begin charging can both reduce network losses but also the risk of unwanted voltage drops.

Afin de satisfaire les besoins futurs en énergie et de réduire l’impact environnemental, l’application de l’énergie renouvelable propre a été récemment reconsidérée. Dans ce contexte, un intérêt croissant pour le système d’alimentation isolé a été mesuré.Le besoin de topologies de faible puissance alimentées par un générateur photovoltaïque, évitant l’utilisation de transformateur, accentue l’étude de systèmes d’alimentation autonomes de basse tension. D’où la nécessité d’étudier les stratégiesde contrôle associées garantissant la stabilité, la fiabilité et l’efficacité.À mesure que les systèmes d’alimentation autonome deviennent plus complexes, les non-linéarités jouent un rôle de plus en plus important dans le comportement du système. La modélisation doit refléter avec précision la dynamique des composants et du système. En outre, les outils d’analyse des systèmes dynamiques devraient être fiable, même dans différents régimes de fonctionnement, fournissant des prédictions précises du comportement de ces derniers. Ce travail est consacré à l’étude d’un système photovoltaïque autonome. La structure proposée se compose d’un panneau photovoltaïque, d’un hacheur et d’une charge connectée en cascade via un bus continu. Les efforts de recherche se concentrent sur le processus de modélisation et l’analyse de stabilité du système. Une implémentation avec une description complète du modèle est ainsi détaillée est validé epar des résultats de simulation. Après avoir donné l’état de l’art, le manuscrit est divisé en quatre parties. Ces parties sont dédiées à la modélisation d’une installation photovoltaïque, à l’amélioration de la simulation numérique, et à l’étude de dynamique de ce système sous contrôles numériques.La thèse présente un aperçu des modèles de générateurs photovoltaïques. Ensuite,un modèle électrique modifié du panneau photovoltaïque est proposé. Nous avons également détaillé le processus de modélisation de l’installation photovoltaïque.Un solveur amélioré de modèle Differential-Algebraic Equations (DAEs) est ensuite développé. Une dixième approche de modélisation est aussi présentée. Nous avons également décrit le système photovoltaïque par un modèle discret simplifié. Ensuite, l’analyse de stabilité du système étudié est détaillée. En outre, nous avons étudié le comportement chaotique qui apparaît dans l’installation photovoltaïque basée sur le hacheur à deux cellules. Le but de la dernière partie est de montrer comment stabiliser l’orbite chaotique du système. Enfin, pour atteindre cet objectif, la commande par retour d’état retardé Time-Delayed Feedback Control (TDFC) est appliquée. / In order to satisfy future energy requirement and reduce environmental impact, application of clean renewable energy, have been reconsidered recently. In this context, a growing interest in isolated power system has been observed. The need of low power topologies fed by photovoltaic array avoiding the use oftransformer open the study of small-scale stand-alone power system. Hence, theneed to study the associated control design strategies ensuring stability, reliability and high efficiency.As systems become more complex, nonlinearities play an increasingly importantrole in stand-alone power system behaviour. Modeling must accurately reflect component and system dynamics. In addition, analysis tools should continue to workreliably, even under various system conditions, providing accurate predictions of systems behaviour.This work is devoted to the study of a stand-alone photovoltaic power system.The proposed structure consists on photovoltaic array, a dc-dc buck converter, anda load connected in cascade through a dc bus. The research efforts focus on themodeling process and stability analysis, which leads to an implementation with acomprehensive description validated through simulation results.After giving the state-of-the-art in second chapter, the manuscript is divided into four chapters. These parts are dedicated to photovoltaic plant modeling, the numeric simulation improvements and dynamic investigation of the photovoltaic system under digital controls.The thesis presents an overview of the photovoltaic generator models. Then, amodified photovoltaic array model is proposed. We also detailed the photovoltaic plant modeling process. An improved Differential-Algebraic Equations (DAEs)solver is then investigated. We also described the photovoltaic system by a simplified discrete model. Then, the dynamic stability analysis is detailled. In addition,we have studied the chaotic behaviour that appears in the photovoltaic plant basedon the two-cell dc-dc buck converter.The aim of the last part is to show, using control theory and numerical simulation,how to apply a method to stabilize the chaotic orbit. Finally, to accomplish this aim, a time-delayed feedback controller is used.

This thesis deals with the management of the fund of alternative investments with an emphasis on photovoltaic projects in the Czech Republic. The main objective is to evaluate whether, after numerous legislative changes, these projects continue to be an attractive investment alternative. The impact of legislative changes on the economy and efficiency of the projects were analyzed for fictitious projects using static and dynamic methods of investment evaluation. The analysis showed that if there was knowledge of the additional cost burden resulting from changes in legislation, then none of the evaluated projects would have been implemented. In general, changes have had the most significant impact on projects that initially appeared to be most effective. In terms of size, restrictions affected mainly smaller projects. Overall, there was a relative alignment of return. For projects with higher levels of debt, an additional cost burden could be liquidational. Then the portfolio of alternative investment fund was created, which consists of assets of two alternative projects evaluated before. This led to evaluation, whether, despite charged fees but a lower tax rate, the investment through the fund is more favorable compared to an own special purpose company. Due to the small size of the fund the hypothesis of fund being more effective mean of administration, was not confirmed.

Orientadores: Rubens Maciel Filho, Fernando Ely / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-22T07:45:29Z (GMT). No. of bitstreams: 1 Matsumoto_Agatha_M.pdf: 4679251 bytes, checksum: 08fb9e84038f307956ec356550160f03 (MD5) Previous issue date: 2013 / Resumo: Células fotovoltaicas orgânicas (OPVs) tem sido foco de intensa pesquisa devido ao seu potencial de baixo custo de produção e pela típica característica de serem flexíveis. Apesar de tais vantagens, estes dispositivos ainda têm baixa eficiência quântica (PCE). Este trabalho explora o desenvolvimento de processos de fabricação reprodutíveis e o uso de novos materiais em estruturas de dispositivo fotovoltaico. Inicialmente foi construído dispositivo padrão seguindo a estrutura de ITO/ PEDOT VpAl/ P3HT:PCBM/ Al, que corresponde à estrutura OPV mais estudada, até hoje, e que conduz a altas eficiências de fotoconversão. Foram ajustados todos os parâmetros físico-químicos para se obter as soluções mais estáveis possíveis e camadas funcionais uniformes do dispositivo padrão. Diversas modificações, neste dispositivo padrão, foram introduzidas para incrementar a eficiência quântica originalmente obtida. Primeiramente, foi testada a aplicação de PEDOT condutor e nanoparticulas (NP) de ZnO como camada buffer em substituição ao PEDOT VpAl. Posteriormente, o composto liquido-cristalino TAPCu-52 foi introduzido como material do tipo-P na camada ativa, em substituição ao polímero P3HT. Cristais líquidos também foram estudados como aditivos funcionais na camada ativa para aumentar a mobilidade dos portadores de carga e facilitar a separação do par elétron-buraco fotogerado. Por fim, buscando tornar o dispositivo completamente flexível foi realizada a substituição do eletrodo transparente de ITO por uma camada de PEDOT condutor, obtida pelo método de spray manual e ultrasônico. As caracterizações elétricas e morfológicas das células OPV, mostraram que todas as modificações feitas levaram a resultados positivos em relação ao dispositivo padrão fabricados / Abstract: Organic photovoltaics (OPVs) have been the focus of research due its flexible characteristics and low cost of production. Despite such advantages these devices still have low quantum efficiency (PCE), which is an obstacle for commercialization. This work explores reliable fabrication processes and new materials for OPV structures. For comparison, we fabricated standard devices having the well studied structure ITO/ PEDOT VpAl/ P3HT:PCBM/ Al which can lead to high fotoconversion efficiencies. Physical and chemical parameters were modified to achieve stable solutions and uniform functional layers. Several modifications in this standard device were introduced in order to increase the original PCE obtained. Firstly, conductive PEDOT and ZnO nanoparticles layers were added in replacement of the PEDOT VpAl as buffer. Afterwards, the liquid-crystalline compound TAPCu-52 was studied as p-type material in the active layer to substitute the P3HT polymer. Liquid crystals were also investigated as functional additives to increase the charge carrier mobility and electron-hole separation. Finally, ITO was changed by a conductive PEDOT layer deposited by handheld and ultrasonic spray as transparent anode in order to have a more flexible device. In general, the electrical and morphological characterizations indicated that all studied modifications had positive effect on the PCE of the manufactured OPV devices / Mestrado / Desenvolvimento de Processos Químicos / Mestra em Engenharia Química

Semiconductor nanocrystals, or quantum dots, have attracted significant interest for use in solid state lighting, biological imaging, photovoltaics, catalysis, and displays such as televisions or tablets. Quantum dots excel in these applications because of their narrow emission profiles, high absorptivity at high energies, and optoelectronic properties that can be easily tuned using colloidal chemistry. The last point in particular has driven the development of new synthetic methods for producing a range of semiconducting materials on the nanoscale. Academically, interest in the synthesis of quantum dots has also extended to the mechanism of their formation and its implications for the growth of nanoscale crystals more generally. This thesis addresses facets of both points above, first by developing several novel syntheses for indium and gallium phosphide nanocrystals, and second by leveraging the synthetic control it allows to study the mechanisms of homogeneous crystal growth. Chapter 1 provides a brief overview of the colloidal syntheses, optoelectronic properties, and formation mechanisms of quantum dots. Emphasis is placed on the development of new chemical syntheses for nanoscale materials and how the size, size distribution, and morphology can be carefully controlled by thoughtful reaction design. The progression of quantum dot synthesis is presented and specific innovations to the precursor and surfactant design are highlighted. Next, a brief discussion about nanocrystal surface chemistry and its impact on the photophysical properties of the inorganic core is described along with its proposed influence on the kinetics of nanocrystal growth. Finally, classical theories of homogeneous crystal growth are presented and used to explain the origin of the exceptionally narrow size distributions accessible in a wide range of materials. Chapter 2 introduces two novel synthetic pathways to InP nanocrystals. The first describes a small library of substituted aminophosphines that can control the precursor conversion reactivity by over an order of magnitude. Leveraging the collection of aminophosphines, it is demonstrated that at sufficiently high temperatures, the rate of precursor conversion can be used to vary the final nanocrystal size—disputing previous findings for InP nanocrystals. We show that the reactivity of the phosphine is governed by a pre-equilibrium between the precursor and an intermediate (P(NHR)3) that goes on to form InP. Variations to the initial aminophosphine substitution pattern change the position of the pre-equilibrium, thereby allowing the rate of [InP]i deposition to be controlled. The second synthetic method leverages metal phosphonate salts as a surfactant to synthesize large samples of InP. We find that the nanocrystals grow via a ripening mechanism and display excellent crystallinity as determined by powder X-ray diffraction and pair distribution function analysis. Finally, we demonstrate that the final nanocrystals are bound by both phosphonates and phosphines through the use of 31P nuclear magnetic resonance spectroscopy. Chapter 3 expands on the syntheses of InP in the previous chapter by developing methods to form GaP, InxGa1-xP, and InP-based core-shell structures. At the onset, two distinct syntheses of GaP are introduced, one similar to the metal phosphonate route used to form InP, and one that used a mixture of amines to stabilize GaP colloidally. The phosphonate method results in small GaP with somewhat indistinct scattering patterns, while the amine method results in large GaP whose morphology can be varied depending on the solvent selected. Leveraging the newly developed InP and GaP syntheses we demonstrate that InxGa1-xP alloys could be directly synthesized from mixtures of In3+ and Ga3+ salts. We also show that InxGa1-xP can be accessed indirectly via cation exchange of Zn3P2 or Cd3P2, however attempts at synthesizing alloys via cation exchange with phosphonate bound GaP were found to be largely unsuccessful. Finally, the chapter contains initial attempts at synthesizing GaP/InP core-shells with the intention of producing GaP/InP/GaP spherical quantum well architectures. Preliminary data show that InP can be deposited using several different methods, though it remains unclear whether the optical properties will be suitable for integration in solid state lighting applications. Chapter 4 examines the crystal growth processes that precede the formation of monodisperse ensembles of InP, PbS, and PbSe nanocrystals. Surprisingly, we find that nucleation persists for a substantial portion of the total reaction time—a stark departure from the canonical “burst” of nucleation proposed originally by Victor LaMer. We go on to measure the nucleation period for a variety of different reaction conditions and find that the fraction of reaction time nucleation extends over is sensitive to both the material and reaction temperature. This is consistent with a mechanism where faster kinetics of monomer attachment reduce the duration of crystal nucleation—a conclusion that can be surmised by nucleation mass balance models that show a clear material and temperature dependence on the rate of nanocrystal growth. We also interrogate the claim that solute molecules accumulate prior to the formation of mature nanostructures. In situ X-ray experiments clearly corroborate the appearance of solute-like species at early reaction times that build up prior to the appearance of crystals with extended structure. Finally, we propose a novel size-focusing mechanism predicated on a size dependent growth rate. Using population mass balance modeling we show that the measurements of size and size distribution are qualitatively consistent with a growth rate inversely proportional to nanocrystal size.

The rapid growth of population and climate change has subjected our civil infrastructures to high load demands and fast aging or degradation over time. Temperature plays a key role in the performance of the aging infrastructure in form of thermal stress and cracking, temperature-induced material aging and degradation, temperature-dependent deformation, and softening. Thus, the importance of predicting the consequent behavior of the infrastructures under environmental conditions becomes imperative. This research characterizes three infrastructure surface materials, namely asphalt pavement, solar panels, and phase change materials (PCM), models the efficacy of modifiers and novel methods to improve their performance and uses these materials in the design and testing of thermal management systems for different applications. The connection between these materials is the thermal management in pavement overlays, which can be extended to other infrastructure surfaces. Asphalt pavement modified with recycled crumb rubber (CR) is a sustainable way to reuse the millions of tires that used to end in landfills. However, the ultraviolet (UV) rays from the sun have been shown to adversely affect the asphalt’s performance in the long run. The severe photo-oxidation can cause changes in the volatile components of the asphalt and result in hardening, aging, and thermal cracks in it. The effect of UV rays on the rubber-modified asphalt may be even more complex due to the presence of crumb rubber particles and their chemical/physical incompatibility and changes in the glass transition. In order to examine these effects, a PG 64-22 is modified with two percentages of 16.6 wt.% and 20.0 wt.% crumb rubber. Results show the specific heat capacities increase with UV aging with 16.6% having the highest value. The addition of the rubber particles does not change the chemical composition of the binder as confirmed by the elemental analysis. However, after UV exposure, peaks associated with carbonyl and sulfoxide are observed, proving that the rubber-modified binder is subject to photo-oxidation as well. The 16.6. wt.% shows the best performance against aging with the lowest sulfoxide index and the highest aliphatic index. Another advantage of adding crumb rubber particles is the formation of a matrix due to the crosslinking of the rubber particles with the binder after being heated, as approved by microscopic images. The carbon nanotubes (CNT) are used to modify the asphalt binder to improve its rheological characteristics while also enhancing the thermal conductivity of the mixture to facilitate the transfer of heat to the surface. In this study, two samples of 3% and 6% multi walled carbon nanotubes (MWCNTs) are prepared using a foaming technology. Foaming the asphalt via water lowers its viscosity and temperature resulting in the saving of the base material and consumed energy while increasing the coating of the aggregates. The results show the CNTs can improve the thermal conductivity of the foamed binder by almost 2X while not negatively affect its rheology. For the other end of the thermal management system, a new hydronic system is introduced for the building integrated photovoltaics and thermal (BIPVT) silicon module that acts for the dual objectives of collecting heat to be used for the thermal management of the pavement and controlling the surface temperature of the solar module itself for the optimal efficiency under different operating conditions. The BIPVT panel with different flow rates of 100 to 600 ml/min were tested for the effectiveness of the cooling design. The results from experiments and simulations show that at 200 ml/min, an optimal balance for the performance of the panel is achieved to not only reduce the temperature of the panel from 88°C to 65°C, but also generate a partially heated water outlet of 37°C (compared with the 23°C inlet) that can be used for the hot water system of the building, or as the inlet feed to the hydronic cooling/heating pavement system. In addition, the BIPVT design proves to restore the power of the solar module by 24.6% at a 200 ml/min flow rate, as confirmed from the I-V curves. Finally, the feasibility study of converting the waste animal fat to a phase change material (PCM) is explored. In PCMs, the high latent heat characteristics are used to store or release energy during the phase change. The use of PCMs can significantly lower the temperature variation of buildings and the consequent energy use. While most common PCMs are paraffin-based and too expensive for large scale applications, a bio-based and more economic alternative could be the key to its vast use in infrastructure systems. However, more research is needed to achieve an animal fat PCM with high latent heat values. In this study, characterizing the raw fat shows a ~20% saturated content. After hydrolysis, the saturated portion has been increased to 65%, but the improvement in the latent is not significant. However, after separation of the fatty acids by use of crystallization, the resulting fully saturated fatty acids (palmitic and stearic acids) show a 3.5X increase in the value of the latent heat, increasing it from ~55 J/g for free fatty acids to ~195 J/g for saturated fatty acids. The promising results of the high latent heat values make the current bio-based PCM a good alternative that needs to be further explored in the future to be used for applications in buildings and BIPVT panels. Overall, the results of this PhD study provide a comprehensive understanding of materials and systems for thermal management of asphalt pavements and enable the design and development of durable self-heated pavements, which can be immediately extended to other infrastructure applications such as wall panels, net-zero buildings, and solar panels.

This thesis comprehensively analyses photovoltaic power plants on facades both from economic and technical point of view. It also devotes to a broader view upon a photovoltaic power plants regarding their placement, its accessories and legislative. The thesis describes a calculation of energetic gains in details including evaluation of five solar radiation sources in order to assess energetic effectivity of the photovoltaic equipment. Furthermore, the thesis describes a means of determination of photovoltaic revenues which is closely related to its ability to sustain the energetic demand of the building. These calculations are presented in the conclusion of thesis where they are applied to four selected buildings. The thesis also contains a processed graph due to which it is possible to specify optimal size of photovoltaic facade. The size is depending on selected facade cardinal point orientation and also on floor area of the building, which serves to estimate future electricity consumption.

The master‘s thesis deals with the issue of weak points of the distribution network in a municipality with high numbers of photovoltaic sources. Photovoltaic power plants are gradually being added to the current state of the electric power distribution network of a specific municipality, while changes in the network are being monitored. Due to the output of the highest possible power from the sources into the distribution system in compliance with the established rules, the thesis also describes network modifications. These established rules of connection and operation of resources in the distribution network and effects of injecting disturbances in the low voltage network are discussed in the theoretical part of the thesis.

This diploma thesis is focused on the issue of connecting new sources to the distribution system and their subsequent operation in the network. The theoretical part describes the conditions of connection and operation of resources in the network according to the established rules. In the practical part, a number of photovoltaic sources and battery vehicles are implemented into the current system according to selected scenarios. Subsequently, the daily course of power flow and voltage conditions in the network is calculated.

This thesis deals with the optimization of power consumption in an intelligent digital home, where the appliances are powered either from a distribution network and also from the photovoltaic source owner. The optimization of consumption we will see both economically and in terms of load distribution network. Renewable power supply operates in a green bonus. Optimization is done using the backup system and the unit Home Manager by SMA. Backup system in collaboration with the batteries will store power from photovoltaic sources, if you're not consumed by appliances in the home. Since it may be a smart home, which is performed by means of inteligent wiring components and accessories (Inels system from the company ELKO EP), is possible thanks to intelligent multimedia extensions and appliances also optimizme consumption.