The dissertation uses the lens of electricity provision to examine processes of state formation in Somaliland, an unrecognized, self-declared independent state in the northwest of the former Somali Republic. The dissertation focuses on Hargeisa, the capital city at the heart of Somaliland's state-building project. After the collapse of the Somali state in 1991, private companies arose from the ruins of Hargeisa and turned the lights back on, navigating a fragmented post-war landscape by mobilizing local connections and transnational ties. However, being dependent on the political settlement that engendered the peace necessary for business, emerging private power providers were tied into a state-building project. The dissertation analyses the resulting tensions at the heart of this project, by examining the struggle to define the role, extents and limits of an emerging state in an interconnected world. Based on interviews in Somaliland and a survey of news media and grey literature, the dissertation has three aims. First, it provides a view into how social order and service provision persist after the collapse of the state. Secondly, it investigates how patterns of provision emerging in the absence of the state shape subsequent processes of state formation. Finally, it discusses how patterns of provision affect the interaction of state-building and market-making. In order to fulfil these aims, the dissertation examines how people invest in the project of building a state, both materially and discursively. The chapters present a narrative history of the electricity sector, explaining the attempts of both private companies and the government to claim sovereignty over the market and shape statehood in their own interests. The struggles shaping Somaliland's economic order reveal the contemporary significance of transnational connections, interconnected systems of capital flows, and the rise of corporate business actors. At the same time, they underline the abiding power of social structure, local identities, and historical memory.

CAPES / As variações de tensão de curta duração são perturbações típicas nos sistemas de distribuição de energia elétrica que afetam de forma significativa a qualidade da energia. Os equipamentos típicos para a regulação de tensão dispostos nas redes de distribuição em geral não são capazes de mitigar variações de tensão de curta duração. Entretanto, as unidades de geração distribuída conectadas aos sistemas de distribuição, considerando estratégias de controle adequadas, podem ser capazes de mitigar variações de tensão de curta duração nas proximidades do ponto de conexão. Nesse contexto, o presente trabalho propõe a mitigação de variações de tensão de curta duração a partir da utilização de unidades eólicas de geração baseadas em gerador síncrono de imã permanente (GSIP) conectado a rede por um conversor estático de potência. A mitigação das variações de tensão é feita por meio de uma malha de controle suplementar proposta aplicada ao controle tradicional do conversor do lado da rede. A estratégia de controle proposta explora a capacidade de operação em sobrecarga de corrente da unidade eólica e é capaz de mitigar variações de tensão de curta duração em sistemas de distribuição. A malha de controle suplementar proposta limita a geração de potência reativa na capacidade máxima de sobrecarga da unidade geradora, respeitando o limite térmico do conversor estático de energia. Além da malha de controle suplementar, uma metodologia baseada em estudos estáticos de fluxo de potência é proposta com o objetivo de avaliar a capacidade de regulação de tensão da geração eólica associada à malha de controle proposta. A capacidade da malha de controle proposta em mitigar as variações de tensão de curta duração é avaliada por meio de simulações não lineares no domínio do tempo envolvendo uma rede de distribuição com cargas concentradas. Diferentes níveis de inserção da geração eólica na rede de distribuição e outros fatores que impactam diretamente na regulação de tensão são considerados nos testes realizados. Os estudos realizados demonstram que utilização da estratégia de controle proposta aplicada a unidades eólicas de geração pode contribuir significativamente para a manutenção do perfil de tensão durante ocorrências de variações de tensão de curta duração. / The short duration voltage variations are typical disturbances that significantly affect the power quality in distribution systems. The typical devices for voltage support and regulation, distributed along the distribution networks, are generally not capable of mitigating short duration voltage variations. However, distributed generation units connected to the distribution system, when associated with suitable control strategies, can be able to mitigate short duration voltage variations. In this context, this paper proposes the mitigation of short duration voltage variations by using wind power generating units based on permanent magnet synchronous generator (PMSG) connected to the network by static power converter. The voltage variation mitigation is performed by means of a supplementary control loop added to the traditional control of the grid-side converter. The proposed control strategy takes advantage of the overload capability of the wind generation unit and it is able to mitigate short duration voltage variations in distribution systems. The proposed supplementary control loop limits the generated reactive power based on the overload capability of the generation unit, avoiding that the power electronic converter exceeds its thermal limit. Besides the proposed supplementary control loop, a methodology based on power flow studies is proposed in order to evaluate the voltage regulation capability of the wind generation associated with the proposed control loop. The performance and effectiveness of the control strategy proposed to mitigate short duration voltage variations is evaluated by means of time-domain non-linear simulations regarding a distribution network with lumped load. Different levels of integration of wind generation on the distribution network and other factors that directly impact on voltage regulation are considered in the tests. The performed evaluations have demonstrated that the proposed control strategy, applied to wind generation units, can significantly contribute to the maintenance of the voltage profile of distribution systems during the occurrence of short duration voltage variations.

Thesis (MTech (Quality)--Cape Peninsula University of Technology, 2009 / There is a South African Government initiative to use State-owned Enterprises (SOE’s) to roll out a programme for the development and stimulation of local small businesses in South Africa. The state has requested SOE’s to set targets on a voluntary basis to increase trade with small businesses, with the purpose of developing small enterprises to eventually enhance skills transfer, training and employment. However, when large customers such as Eskom Nuclear Generation require ISO certification as a prerequisite for a supplier to provide goods and/or services to them, most small businesses are unable to comply. The requirement of ISO9000 compliance inhibits the ability of most small businesses to compete with their larger counterparts. Small businesses constitute as much as 90% of most world economies. They have many advantages to offer customers, such as a high level of flexibility, innovation and responsiveness to customer needs. These attributes can introduce healthy competition to the supply chain. Small businesses, by their very nature experience more risks, such as a higher vulnerability to volatile market forces and skills loss. In addition, they are generally less specialised. They are under continuous competitive pressure, and are generally not able to provide assurance of a sustainable product over a longer period. Although there is an imperative to develop and use small suppliers, they introduce higher risk to the supply chain. The primary research objective of this dissertation is to develop a robust model to identify risks inherent to small businesses, and to propose measures to mitigate such risks. A classification of problems with small suppliers that have occurred at Koeberg Nuclear Power Station over a period of 3 years (from June 2005 to May 2008), will form the basis of the research methodology. The anticipated findings of the research include the following. _ Several common critical issues of failure will be identified in the internal processes of small suppliers, with variations between types of suppliers, which will indicate which elements within the context of ISO9000 can be applied to address shortcoming in the suppliers’ processes. _ A matrix will be compiled from this by which the customer can identify the type of supplier, the types of risks inherent to that supplier, and which elements of ISO9000 the customer should insist upon to be adopted into an elementary quality management system of that small supplier. This should be executed as part of a larger supplier development programme.

Wind generation is one of the most successful sources of renewable energy for the production of electrical energy. Wind power offers relatively high capacities, with generation costs that are becoming competitive with conventional energy sources. However, a major problem to its effective use as a power source is the fact that it is both intermittent and diffuse as wind speed is highly variable and site-specific. This is translated in large voltage and frequency excursions and dynamically unstable situations when fast wind power changes. Very high wind speeds will result in sudden loss of wind generator production. The requirement to ensure that sufficient spinning reserve capacity exists within the system to compensate for sudden loss of generation becomes crucial. From the utilities operators’point of view, the primary objective is the security of the system, followed by the quality of the supplied power.<p>In order to guard the system security and quality of supply and retain acceptable levels, a maximum allowed wind power penetration (wind margin) is normally assumed by the operators. Very conservative methods are used to assess the impact of wind power and the consequences turn to under-exploitation of the wind power potential in a given region. This thesis presents the study of actual methods of wind power assessment, divided into three parts:<p>1. Part I: Impact on the Security of Power Systems<p>2. Part II: Impact on the Power Quality<p>3. Part III: Impact on the Dynamic Security of Power Systems / Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished

This diploma thesis is concerned with the design of the machinery with an extraction steam condensing turbine in Precheza corp. The theoretical part of this thesis describes the energetical situation in the company and the primary consideration about recovery of the heat, released at sulphuric acid production, for electrical power production. There is also presented brief description of the sulphuric acid production and the fundamental principles of the steam production at this process. In the practical part of this thesis there is performed the calculation of the heat-flow diagram of the steam turbine and the calculation of heat and producted electrical power at the basic operational states. There is presented the source code for the calculation of the heat-flow diagram using Matlab software. In the end there is mentioned the economical evaluation of the whole project, using the fundamental economical methods, such as net present value method, or profitability index, including the calculation of the pay-back period.

Der vorliegende Beitrag entstand im Rahmen der Arbeiten von Teilprojekt C2 „Betreibungs- und Koordinierungsstrukturen“ im Sonderforschungsbereich 457. Die Forschungsarbeit des SFB 457 “Hierarchielose regionale Produktionsnetze“ fokussiert den visionären Ansatz einer kundenorientierten Vernetzung von Klein- und Kleinstunternehmen einer Region. Diese als Kompetenzzellen (KPZ) bezeichneten kleinsten nicht mehr sinnvoll teilbaren Leistungseinheiten kooperieren in hierarchielosen Produktionsnetzen und stellen sich auf diese Art und Weise dem globalen Wettbewerb.

This thesis estimates the impacts of rooftop photovoltaic (PV) capacity on electricity generation and CO2 emissions in America's Pacific Northwest. The region's demand for electricity is increasing at the same time that it is attempting to reduce its greenhouse gas emissions. The electricity generated by rooftop PV capacity is expected to displace electricity from fossil fueled electricity generators and reduce CO2 emissions, but when and how much? And how can this region maximize and focus the impacts of additional rooftop PV capacity on CO2 emissions? To answer these questions, an hourly urban rooftop PV generation profile for 2009 was created from estimates of regional rooftop PV capacity and solar resource data. That profile was compared with the region's hourly fossil fuel generation profile for 2009 to determine how much urban rooftop PV generation reduced annual fossil fuel electricity generation and CO2 emissions. Those reductions were then projected for a range of additional multiples of rooftop PV capacity. The conclusions indicate that additional rooftop PV capacity in the region primarily displaces electricity from natural gas generators, and shows that the timing of rooftop PV generation corresponds with the use of fossil fuel generators. Each additional Wp/ capita of rooftop PV capacity reduces CO2 emissions by 9,600 to 7,300 tons/ year. The final discussion proposes some methods to maximize and focus rooftop PV impacts on CO2 emissions, and also suggests some questions for further research.

[pt] Problemas de emissão de gases de efeito estufa vem sido amplamente discutidos nos últimos anos, uma vez que mais de 70 países já se comprometeram a uma economia neutra em carbono até 2050. A eletrificação dos modais de transporte tem sido ampliadas seguindo essas metas, onde os Veículos Elétricos (VEs) começam a ganhar participação sobre o mercado de Veículos com Motor de Combustão Interna (VMCI) por todo o mundo. Além da particular complexidade na comparação entre VEs e VMCIs, desafios envolvendo a natureza dos VEs e sua integração com as cidades, como a falta de locais públicos para recarga, também são críticos e interferem no seu desenvolvimento. Nesse contexto, este trabalho visa estudar o problema de uma Estação de Troca de Baterias (ETB), uma estrutura onde os usuários de VEs trocam suas baterias descarregadas por outras totalmente ou parcialmente carregadas. No intuito de simular as operações diárias do ETB e o cronograma de carregamento das baterias, um novo modelo de Programação Linear Inteira Mista (PLIM) é proposto, levando em consideração a heterogeneidade da bateria, o uso de geração fotovoltaica (PV) local e a degradação da bateria com base no perfil de carregamento. Uma coleção de métricas de operação do ETB é projetada para avaliar a qualidade da solução do modelo de cronograma proposto. É apresentado um experimento numérico que compreende quatro estudos de caso baseados em dados reais dos sistemas de energia e transporte dos EUA, contendo insights e análises sobre o uso da energia fotovoltaica e da rede, bem como uma comparação financeira do ETB com abordagens de cronograma de benchmarks relacionados, juntamente de sensibilidades no plano de dimensionamento do ETB e atendimento a clientes. / [en] Greenhouse gas emissions-related issues have been extensively discussed in the past years, with over 70 countries already committed to a carbon-neutral economy by 2050. The electrification of transportation modals has increased following these goals, where Electric Vehicles (EVs) are starting to take Internal Combustion Engine Vehicles (ICEV) market share all over the globe. Besides the particular complexity in comparing EVs and ICEVs, challenges involving the nature of EVs and their integration with cities, such as the lack of public locals for charging, are also critical and interfere with their development. In this context, this work aims at studying the problem of a Battery Swapping Station (BSS), a structure where the EVs users swap their depleted batteries for fully or partially charged ones. In order to simulate the BSS daily operations and batteries charging schedule, a novel Mixed Integer Linear Programming (MILP) model is proposed, taking into account battery heterogeneity, the use of local photovoltaic (PV) production and battery degradation based on charging profile. A collection of BSS operation metrics are designed to evaluate the solution quality of the proposed scheduling model. A numerical experiment comprising four case studies based on real data from the US power and transportation systems is presented, with insights and analyses on the PV and grid power use, as well as a BSS financial comparison against close-related benchmark scheduling approaches, together with sensitivities on BSS sizing plan and costumers attendance.

Cette thèse s’intéresse à la problématique de la prédiction dans le cadre du design de systèmes énergétiques et des problèmes d’opération, et en particulier, à l’évaluation de l’adéquation de systèmes de production d’énergie renouvelables. L’objectif général est de développer une approche empirique pour générer des prédictions avec les incertitudes associées. En ce qui concerne cette direction de la recherche, une approche non paramétrique et empirique pour estimer les intervalles de prédiction (PIs) basés sur les réseaux de neurones (NNs) a été développée, quantifiant l’incertitude dans les prédictions due à la variabilité des données d’entrée et du comportement du système (i.e. due au comportement stochastique des sources renouvelables et de la demande d'énergie électrique), et des erreurs liées aux approximations faites pour établir le modèle de prédiction. Une nouvelle méthode basée sur l'optimisation multi-objectif pour estimer les PIs basée sur les réseaux de neurones et optimale à la fois en termes de précision (probabilité de couverture) et d’information (largeur d’intervalle) est proposée. L’ensemble de NN individuels par deux nouvelles approches est enfin présenté comme un moyen d’augmenter la performance des modèles. Des applications sur des études de cas réels démontrent la puissance de la méthode développée. / This Ph.D. work addresses the problem of prediction within energy systems design and operation problems, and particularly the adequacy assessment of renewable power generation systems. The general aim is to develop an empirical modeling framework for providing predictions with the associated uncertainties. Along this research direction, a non-parametric, empirical approach to estimate neural network (NN)-based prediction intervals (PIs) has been developed, accounting for the uncertainty in the predictions due to the variability in the input data and the system behavior (e.g. due to the stochastic behavior of the renewable sources and of the energy demand by the loads), and to model approximation errors. A novel multi-objective framework for estimating NN-based PIs, optimal in terms of both accuracy (coverage probability) and informativeness (interval width) is proposed. Ensembling of individual NNs via two novel approaches is proposed as a way to increase the performance of the models. Applications on real case studies demonstrate the power of the proposed framework.

From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / An examination of potential water sources for power plant cooling in Arizona is presented along with information pertinent to Arizona's future water needs relative to electrical usage growth. It has been projected that Arizona's peak electrical power demands in 1980 and 1990 will exceed that of 1970 by some 5000 megawatts and 16000 megawatts of electricity respectively. At present, the bulk of the electrical energy generated in the western states originates at hydroelectric installations. Utilization of nuclear reactors for power generation requires a larger amount of cooling water than is required for a comparable fossil-fueled plant. It is suggested that the utilization of reclaimed wastewater for cooling purposes is a viable and attractive alternative to groundwater pumpage from both economic and ecological standpoints. Savings arise from conservation of fuel normally required for well pumps, costs of well construction are not required, quantities of fresh water should be released for consumption by alternate users, and a previously unused resource would be effectively recycled.