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<p>  </p> <p>  </p> <p>Concentrator photovoltaics have demonstrated greater solar energy production efficiency than previous solar electric technologies.  However, recent research reveals that heat management is a significant difficulty in CPV systems, and if left unaddressed, it can have a severe influence on system efficiency and lifetime. Traditional CPV cooling relies on active methods such as forced air convection, or liquid cooling, which might lead to an extremely large parasitic power use. In addition, the moving parts of a cooling system result in a shorter lifespan and higher maintenance expenses. </p> <p><br></p> <p>CPV systems can boost their efficiency and lifespan by adopting passive cooling solutions. This work employed radiative cooling and natural convection to construct an efficient and cost-effective cooling system. The excess heat of a solar cell can be dispersed into space via electromagnetic waves via radiative cooling. Due to the fact that the radiative cooling power is related to the difference between the fourth powers of the solar cell and the ambient temperature, much greater cooling powers can be obtained at higher temperatures. Heat pipes were installed to act as a heat pump by transferring excessive heat from solar cells within a system to the exterior, where it can be dissipated via natural air cooling and thermal radiation. Experiments conducted in this study demonstrate that a temperature reduction of 21 ◦C was accomplished through radiative cooling and natural convection, resulting in an increase of 64 mV, or 17% in the open-circuit voltage of a GaSb solar cell.</p>

<p>The ongoing and rapidly accelerating integration of inverter-based resources (IBRs), such as solar panels, into power distribution systems has heightened the importance of computational tools that can be used to study the dynamics of such systems. IBRs use power electronics to interface the energy sources to the grid, thereby introducing faster dynamics than their electromechanical counterparts, which could lead to instabilities in distribution systems and microgrids. Hence, there is a need for conducting simulations of distribution systems containing large numbers of single- and three-phase inverters, which could be operating under either grid-following or grid-forming modes.</p> <p>A key objective of this thesis is to derive detailed, high-fidelity models of inverters and their controls in the context of unbalanced distribution networks. In addition, a diesel synchronous generator model is derived, for the sake of completeness. The main contribution of this work is that these models are developed for use in a novel simulation toolbox called Dynamic Simulation Tool using a Sparse Tableau Approach in Python, DynaSTPy (pronounced dynasty). This thesis outlines how the components can be modeled in the sparse tableau framework as electrical networks with topology described using a node-branch incidence matrix. In addition, the thesis explains how controller dynamics and constraints can be handled within this framework. These models are tailored to seamlessly integrate into the DynaSTPy toolbox. The proposed approach can be readily extended to model other such components in the future.</p>

<p dir="ltr">Batteries have become essential for a wide range of applications in the field of energy storage and electrification, from portable gadgets to electric cars and renewable energy systems. But effectiveness, performance, and lifespan of a battery pack are closely related to each of the individual cells of which it is composed. The phenomenon of cell voltage imbalance, which can result in a variety of problems ranging from decreased capacity and efficiency to safety concerns and premature failure, poses a significant challenge in managing battery systems.</p><p dir="ltr">Therefore, battery cell balancing plays a crucial role in improving the overall performance of battery packs. To guarantee uniform charge and discharge characteristics, balancing is the process of equalizing the charge of individual cells inside a battery pack. Battery cell balancing seeks to prolong the operational life of packs, improve the efficiency of its energy use, and ensure the safety of the overall system.</p><p dir="ltr">The methods used for battery cell balancing encompass a wide range of approaches, from passive methods that release extra energy as heat, to active methods that move energy across cells. The particular battery chemistry, application requirements, and required level of balancing precision are only a few examples of the variables that influence the choice of balancing technique.</p><p dir="ltr">Lithium Iron Phosphate (LiFePO4) rechargeable batteries are widely used by electric utility companies in battery storage applications. Battery cells are combined to form a battery module. Each module is constantly monitored with sensors and controlled by a Battery Management System (BMS). The BMS performs balancing of the cells. Each cell in the battery stack is monitored to maintain a healthy battery state of charge (SoC). The motivation for this work is to develop an active balancing system to replace a passive system currently being performed manually on an existing battery storage system consisting of LiFePO4 cells. An active cell balancer was designed using the LT8584 active cell balancer, which is based on a flyback DC-DC converter design. An LTspice simulation of the design was created for a single cell. It demonstrates critical parameters of the flyback converter cycle time. A PCB board, designed using KiCAD, was implemented. It is anticipated that the proposed design could be used to restore the health of SoC of faulty modules in lieu of removing and replacing them with a new module, resulting in potential cost savings. The proposed design is scalable in that it could be used for <i>n</i> number of cells in a battery module consisting of LiFePO4 battery cells.</p>

<p dir="ltr">The urgent global shift towards decarbonization necessitates the development of robust frameworks to navigate the complex technological, financial, and regulatory challenges emerging in the clean energy transition. Furthermore, the increased adoption of renewable energy sources (RES) is correlated to the exponential growth in weather data research over the last few years. This circular relationship, where big data drives renewable growth, which feeds back the data pipeline, serves as the primary focus of this study: the development of computational tools across diverse spatial and temporal scales for the optimal design and operation of renewable energy-based systems. Two scales are considered, differentiated by their primary objectives and techniques used. </p><p dir="ltr"> In the first one, the integration of probabilistic forecasts into the operations of RES microgrids (MGs) is studied in detail. It is revealed that longer scheduling horizons can reduce dispatch costs but at the expense of forecast accuracy due to increased prediction accuracy decay (PAD). To address this, a novel method that determines how to split the time horizon into timeblocks to minimize dispatch costs and maximize forecast accuracy is proposed. This forms the basis of an optimal rolling horizon strategy (ORoHS) which schedules distributed energy resources over varying prediction/execution horizons. Results offer Pareto-optimal fronts, showing the trade-offs between cost and accuracy at varying confidence levels. Solar power proved more cost-effective than wind power due to lower variability, despite wind’s higher energy output. The ORoHS strategy outperformed common scheduling methods. In the case study, it achieved a cost of \$4.68 compared to \$9.89 (greedy policy) and \$9.37 (two-hour RoHS). The second study proposes the Caribbean Energy Corridor (CEC) project, a novel, ambitious initiative that aims to achieve total grid connectivity between the Caribbean islands. The analysis makes use of thorough data procedures and optimization methods for the resource assessment and design tasks needed to build such an infrastructure. Renewable energy potentials are quantified under different temporal and spatial coverages to maximize usage. Prioritizing offshore wind development, the CEC’s could significantly surpass anticipated growth in energy demand, with an estimated installed capacity of 34 GW of clean energy upon completion. The corridor is modeled as an HVDC grid with 32 nodes and 31 links. Underwater transmission is optimized with a Submarine-Cable-Dynamic-Programming (SCDP) algorithm that determines the best routes across the bathymetry of the region. It is found that the levelized cost of electricity remains on the low end at \$0.11/kWh, despite high initial capital investments. Projected savings reach \$ 100 billion when compared with ”business-as-usual” scenarios and the current social cost of carbon. Furthermore, this infrastructure has the potential to create around 50,000 jobs in construction, policy, and research within the coming decades, while simultaneously establishing a robust and sustainable energy-water nexus in the region. Finally, the broader implications of these works are explored, highlighting their potential to address global challenges such as energy accessibility, prosperity in conflict zones, and sharing these discoveries with the upcoming generations.</p>

Thesis (MBA (Business Management))--University of Stellenbosch, 2008. / AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse Heropbouings Program (HOP) asook die Groei Indiensnemings- en Herverdelingsprogram(GEAR) het ‘n geweldige hoë standaard gestel vir die verskaffing van basiese dienste soos behuising en elektrifisëring vir almal. Die meer effektiewe gebruik van elektriese energie het die sosiale en politieke potensiaal om by te dra tot die sukses van GEAR ten opsigte van die geteikende lae inkomste gemeenskappe waar daar nie tans voldoende elektriese energie beskikbaar is nie. Hierdie studie dek ook die inisiatiewe ten opsigte van effektiewe elektriese energie waaroor die Suid-Afrikaanse regering in vennootskap met Eskom tans navorsing doen om te bepaal of daar enige ekonomiese waarde is, en/of die lae inkomste gemeenskappe deur die sogenoemde inisiatiewe bevoordeel kan word. Die studie sluit ook navorsing in om die bewustheid van die lae inkomste gemeenskappe ten opsigte van effektiewe elektriese energie te bepaal. Die studie kyk verder na verskeie ander voltooide studies ten opsigte van effektiewe energie in lae inkomste gemeenskappe. Alhoewel verskeie ander effektiewe energie programme wel hoë ekonomiese en omgewings voordele uit 'n sosiale oogpunt inhou, is dieselfde programme glad nie aantreklik vir die verbruikers nie. Vir hierdie feit is die regering se bemiddeling wel belangrik. Die uitslag van die studie ondersoek ook die verskillende beleidsopsies (nie in diepte nie) om die struikelblokke van effektiewe energie te oorkom, asook moontlike oplossings vir die regering om die verskille tussen wat goed is vir die gemeenskap, en wat goed is vir die elektriese industrie te oorbrug. Die studie toets ook die bewustheid van effektiewe energie onder die lae inkomste gemeenskappe en hul huidige deelname aan effektiewe energie programme. / ENGLISH ABSTRACT: South Africa’s Reconstruction and Development Programme (RDP) as well as Growth Employment and Redistribution (GEAR) set ambitious goals for providing basic services to all, including housing and electrification. More efficient use of electrical energy has the potential to socially and politically support the goals of GEAR, particularly when it is targeted at low-income communities lacking adequate energy services. This study looks at electrical energy efficiency initiatives that the South African government has under taken on its own as well as in partnership with Eskom and to check if there is any economic value that the poor communities may benefit from these initiatives. The study will also check the awareness of poor communities of electrical energy efficiency. Various studies in the subject of energy efficiency in relation to the poor communities that have been done in the past will also be looked at in this study. While many energy efficiency programmes may have significant economic and environmental benefits from a social perspective, they may not be as attractive to utilities and consumers. That is why government intervention is important. As a result this study also examine (not in great depth) the policy options for overcoming the significant barriers to energy efficiency, and ways government can bridge the gap between what is good for society and what is good for the electricity industry. This study extends further on checking the awareness of energy efficiency by the poor communities and their current participation in the energy efficiency programmes.

[pt] Nos últimos anos, o custo com energia elétrica tem aumentado de forma significativa para os consumidores no Brasil. Grandes consumidores, como indústrias e comércios, atualmente dispõem de alternativas para mitigar estes custos, como a otimização do contrato de demanda, a correção do baixo fator de potência, a utilização de geração própria, renovável ou não renovável, além da possibilidade de migrar para o mercado livre de energia elétrica, com diversas modalidades de contratos, preços e prazos. Já os consumidores residenciais, em função dos custos menores com as faturas de energia e da limitação técnica dos medidores, até agora dispunham de poucos mecanismos para atenuar seus custos. Entretanto, nos últimos anos tem sido cada vez mais comum a utilização de geração distribuída, principalmente com o uso de painéis fotovoltaicos por parte destes consumidores. Além disto, com a redução dos custos dos medidores inteligentes de energia elétrica, estes consumidores também podem monitorar seu consumo em tempo real, promovendo ações de aumento de eficiência energética para reduzir custos. Mais recentemente, foram criadas as bandeiras tarifárias, que propõem identificar as condições sistêmicas por cores verde, amarela e vermelha. As cores amarela e vermelha sinalizam aumentos de custos na produção de energia elétrica e, consequentemente, são repassados para o consumidor na forma de aumento de tarifa, promovendo resposta da demanda. Assim, há uma razão adicional para os consumidores monitorarem seu consumo. Não obstante, em 2018 foi adotada uma nova modalidade tarifária voltada para esta classe de consumidor chamada tarifa branca. Nesta modalidade, o consumidor possui diferentes valores de tarifas para diferentes períodos do dia. Assim, o consumidor que optar por esta modalidade pode reduzir o custo da sua fatura deslocando o consumo de horários de maior valor de tarifa para horários de menor valor de tarifa. Esta dissertação busca analisar em detalhes a viabilidade de um consumidor residencial migrar seu contrato para a chamada tarifa branca. Para isto, é proposto um modelo de otimização linear inteiro misto que busca desagregar o consumo de energia elétrica, medido de forma não invasiva, do consumidor para os diferentes eletrodomésticos da casa. Logo, o consumidor poderá decidir pela mudança contratual avaliando a perda de conforto que terá em mudar seus hábitos de consumo. A aplicação do modelo proposto é interessante não só por apresentar um diagnóstico mais detalhado do consumo de energia elétrica, mas também por identificar o funcionamento de eletrodomésticos como geladeira, ar condicionado e frigobar, que possuem diferentes estados de operação que dificilmente seriam capturados por uma simples inspeção destes eletrodomésticos. Para ilustrar o modelo proposto, nesta dissertação, dados de um consumidor real foram utilizados e a acurácia do modelo pôde ser comprovada com medições diretas de alguns eletrodomésticos. Desta forma, o consumidor tem a sua disposição uma ferramenta de apoio à decisão importante para monitorar o funcionamento dos eletrodomésticos e definir se deve migrar para a nova modalidade tarifária. / [en] In the last years, energy consumption has increased significantly for consumers in Brazil. Large consumers, such as industrial and commercial customers, are currently subject to cost-mitigation alternatives such as demand contract optimization, power factor reduction, self-generation, renewable or non-renewable generation, and the possibility of migrating to the free market of electric energy, with various modes of purchase, prices and deadlines. The consumer, in which the means of the upper costs with the fat means of the data of the meters, is in function of minor engines to reduce their costs. However, on a constant basis, with the use of photovoltaic panels, by these consumers. In addition, with the help of the costs of smart electric power meters, these profits are potentially higher, in real time, the ability to generate weaker sound profits for the cost image. More recently, they were created as tariff plates, which identify the systemic conditions by the green, yellow and red nuclei. The yellow and red samples are generated from the temperature of electric energy production and, consequently, are passed on to the consumer in the form of temperature increase. Thus, there is a large difference in consumption levels of your consumption. Nevertheless, in 2015 a new tariff modality was implemented for this class of energy consumption called the white tariff. In this mode, the buyer has different rate values for different periods of the day. Thus, consumers who have this option can reduce the cost of their invoice in relation to the consumption of schedules of higher tariff value for the hours of lower tariff value. This dissertation looks at the analysis on a feasibility of a residential ad migrating its contract to a so-called white tariff. To this end, it is necessary a linear model that makes the difference in consumption of electric energy, measured non-invasively, from consumer to the different units of household appliances of the house. Therefore, the consumer is also evaluated by contracting a service that improves their consumption capacity. The application of the model is more interesting, but no longer presents the power of electric power, but also has the same standard of electricity as the refrigerator, air conditioning and minibar, which have different states of operation that are hardly captured by a simple inspection of each appliance. To illustrate the proposed model, this dissertation, data from a real consumer were used and an accuracy of the model can be proven with the direct measurements of some home appliances. The way in which the consumer has a migration support tool for the operation of the equipment and defines whether to migrate to a new tariff modality.

Made available in DSpace on 2016-04-04T18:32:43Z (GMT). No. of bitstreams: 1 Maria Lucinda A de Lucena.pdf: 2279192 bytes, checksum: 1a8bc7775f597640549f110da92f81e6 (MD5) Previous issue date: 2008-02-22 / The present moment in history is characterized by the incessant search for new models that can answer the recent human and social demands of growing complexity that emerge in our society marked by constant transformations. This work analyzes and reflects on the managerial formation of Engineers who eventually arrive at managerial positions in companies of the electrical energy sector during their careers. Besides bringing to light the historical and social importance of the sector, the study surveys and examines questions related to knowledge in the contemporary world and its implications in the productive sector and consequently in corporative education too. It questions the integral development of the human being in this process by emphasizing contradictions between theory and practice, intentions and objectives, technical and humanistic formation and objectives and results. To develop the study, semi-structured interviews, inventories and questionnaires were applied in order to collect data and information about the managerial formation of Engineering Managers in private or public enterprises. It is hoped that the result of the study will be contributions for the growth of knowledge of the actual reality, increasing values for the formation of future Engineers and Engineering Managers and the creation of scientific, social and cultural support for them. It is also hoped that creation of new proposals for academic as well as organizational education will be possible, promoting a systematic relationship between universities and companies. This would stimulate the transformation of managerial programs developed in the corporations, promoting a formation of Engineers and Engineering Managers that is complete and directed to forming Integral Human Beings. / O momento hist?rico atual tem se caracterizado pela forte busca de novos modelos que possam dar conta das recentes demandas humanas e sociais, cada vez mais complexas que emergem em nossa sociedade marcada por constantes transforma??es. Este trabalho visa analisar e refletir sobre a forma??o gerencial dos Engenheiros que no decorrer de sua carreira profissional rumaram para o exerc?cio da fun??o gerencial em empresas do Setor de Energia El?trica. Al?m do resgate da import?ncia hist?rica e social do Setor, procura levantar e examinar as quest?es relativas ao conhecimento no mundo contempor?neo e suas implica??es no setor de produ??o e conseq?entemente na educa??o corporativa. Problematiza a quest?o do desenvolvimento do Ser Humano Integral nesse processo, procurando salientar as contradi??es entre teoria e pr?tica; inten??es e objetivos, forma??o t?cnica e forma??o human?stica; objetivos e resultados. Para dar conta do trabalho foram realizadas entrevistas semi-estruturadas, aplica??o de invent?rios, e question?rios, com a finalidade de coletar dados e informa??es sobre a forma??o gerencial dos Engenheiros-Gestores tanto nas empresas privadas ou n?o. Como resultado do estudo s?o esperadas contribui??es para a amplia??o do conhecimento da realidade atual, agregando valores para a forma??o das futuras gera??es de Engenheiros e Engenheiros Gestores, criando um aporte cient?fico, social e cultural. ? esperada tamb?m a possibilidade de gera??o de novas propostas para a educa??o tanto na academia como nas organiza??es, incitando o relacionamento sistem?tico entre universidades e empresas, estimulando a transforma??o dos programas gerenciais desenvolvidos nas corpora??es, fomentando a forma??o de Engenheiros e Engenheiros-Gestores orientados para uma forma??o plena como Ser Humano Integral.

Este trabalho tem por objetivo desenvolver uma abordagem fuzzy focando na estimação de curto prazo da demanda de potência ativa de um alimentador de sistema de distribuição de energia elétrica. A motivação para este trabalho encontra-se na redução do erro de estimação para que o sistema de distribuição como um todo seja corretamente operado. O destaque da abordagem desenvolvida é a metodologia de seleção de entradas para o sistema de estimação, que o treina fornecendo-lhe informações não redundantes e não desnecessárias sobre o comportamento da série temporal. Os resultados, obtidos com treinamento e teste de um sistema de inferência fuzzy multicamadas, mostram que as estimações realizadas selecionando as entradas do sistema de forma criteriosa apresentam menor erro que quando não há critério de seleção. Conclui-se então que a metodologia foi funcional e eficiente para o caso estudado, o que faz com que este trabalho resulte em válidas contribuições nas áreas de sistemas inteligentes, de sistemas dinâmicos e inclusive na forma metodológica de especificação de modelos de estimação de séries temporais. / This work aims to develop a fuzzy approach focusing on the short-term active power demand forecast in a feeder of an electrical energy distribution system. This work motivation lies on the reduction of the forecast error so that the whole distribution system can be correctly operated. The highlight of the developed approach is the methodology to select the inputs for the estimation system, which trains it giving to it non-redundant and non-unnecessary information about the time series behavior. The results, obtained by training and testing a multilayer fuzzy inference system, show that the estimations made by following a criterion to select the inputs have smaller error than when there is no selection criterion at all. It is therefore concluded that the methodology was functional and efficient for the case under study, what makes this work result in valid contributions for the fields of intelligent systems, dynamic systems and in the methodological way to specify models to estimate time series.

Zur Verminderung der Kosten und zur Erhöhung der Zuverlässigkeit ist es zukünftig erforderlich, den Verkabelungsaufwand bei Sensoren im Kraftfahrzeug zu senken. Ein Ansatz ist der so genannte autarke Sensor, der seine Hilfsenergie drahtlos aus dem Umfeld gewinnt und seine gewonnen Messdaten ebenfalls drahtlos an einen Kommunikationspunkt überträgt. In der vorliegenden Dissertation wurde die autarke Energiegewinnung für Sensoren anhand mechanisch / elektrischer Energiewandlersysteme untersucht, die eine von Kabelverbindungen unabhängige Energieversorgung des Sensors ermöglichen sollen. Für ein System, welches aus einem translatorischen Schwinger mit magnetischer Federung und einer Anordnung von Induktionsspulen ohne Eisenkreis besteht, wurden theoretische und praktische Untersuchungen durchgeführt. Ausgehend von der, die Bewegung des Systems beschreibenden Differentialgleichung wurden die Einflüsse verschiedener Federungs- und Dämpfungskräfte untersucht. Daraus wurde eine effektive Schwingungsgleichung abgeleitet und hinsichtlich der Amplitude und der Phase gelöst. Die umgesetzte elektrische Leistung des Wandlers wurde aus dem Realteil des Stromflusses abgeleitet. Mit einem realen Fahrzeug wurden Testfahrten durchgeführt, um verschiedene signifikante Fahrbahndaten zu erhalten. Mit diesen Prozessparametern erfolgten später Messungen im Labor. Dafür wurde ein Schwingprüfstand aufgebaut und mehrere Funktionsmuster von Energiewandlersystemen untersucht. / In the future a decrease in sensor cabling inside vehicles becomes of greater importance to reduce cost and increase reliability. One approach is the so called autarkic sensor that generates energy wireless from the sensor's environment and transmits the derived measuring data also wireless to a communication node. Purpose of this dissertation is to discuss the autarkic energy recovery sensors based on a mechanical to electrical conversion which should allow a cable less energy supply. Theoretical and practical tests where made for a system which consists out of a translatory vibration with magnetic suspension and coreless coils. Starting from the differential equations describing the movement of the system, the influence of different ways of suspension and damping forces where investigated. As a result, the actual equation of oscillation was derived and solved with respect to amplitude and phase. The gained electrical power was derived from the real part of the current. Multiple test runs inside a car where performed to obtain some realistic measurement values. Based on those measurements, a test stand was set up inside the laboratory which should simulate normal road conditions. Using this test stand, multiple functional models of energy converting systems were investigated.