Dissertations / Theses on the topic 'Distribution of total power consumption'

Магістерська дисертація «Підвищення енергетичної ефективності гімназії новітніх біотехнологій №177» складається з 123 сторінок, 15 рисунків, 57 таблиць, а також містить 20 джерел в переліку посилань. Метою роботи є визначення доцільності проведення термомодернізації та моделювання геліосистеми для гарячого водопостачання у програмному середовищі. Завдання дослідження – розрахунок теплових та електричних навантажень, аналіз енергоспоживання, визначення економічного ефекту впровадження заходів з енергозбереження. Предмет дослідження – вивчення конструктивних і енергетичних характеристик об’єкту при розробці різних сценарних варіативних моделей та географічного розташування. Наукова новизна магістерської дисертації полягає у оцінюванні фінансових показників проекту термомодернізації будівлі двома шляхами: розрахунок ефективності окремо кожного заходу та моделювання геліосистеми у програмному середовищі Tsol. Результати досліджень були апробовані та викладені на 2-й науково-технічній конференції магістрантів ІЕЕ 21 – 22 листопада 2019.
Master's thesis «Improving the energy efficiency of the high school of the latest biotechnology №177» consists of 123 pages, 15 figures, 57 tables, and also contains 20 sources in the list of references. The purpose of the work is to determine the expediency of thermo-modernization and modeling of the solar system for hot water supply in the software environment. Task of the research - calculation of thermal and electrical loads, analysis of energy consumption, determination of the economic effect of the implementation of energy conservation measures, to study the solar energy potential of Ukraine, determining the feasibility of using the solar system for hot water needs. The subject of the study is the study of the constructive and energy characteristics of the object in the development of various scenario variational models and geographic location. Actuality is the effective use of solar energy in solar systems in climates Ukraine for energy purposes. The object of study- a preschool institution №712. The scientific novelty of the master's thesis consists in evaluating the financial indicators of the project of thermo-modernization of a residential building in two ways: the calculation of the efficiency of each measure separately and modeling the solar system in the Tsol software environment.

The objective of this thesis is to estimate, for a distribution network, confidence intervals containing the values of nodal hourly power consumption and nodal maximum power consumption per customer where they are not measured. The values of nodal hourly power consumption are needed in operational as well as in planning stages to carry out load flow studies. As for the values of nodal maximum power consumption per customer, they are used to solve planning problems such as transformer sizing. Confidence interval estimation was preferred to point estimation because it takes into consideration the large variability of the consumption values. A computationally intensive statistical technique, namely the bootstrap method, is utilized to estimate these intervals. It allows us to replace idealized model assumptions for the load distributions by model free analyses.

Two studies have been executed. The first one is based on the original nonparametric bootstrap method to calculate a 95% confidence interval for nodal hourly power consumption. This estimation is carried out for a given node and a given hour of the year. The second one makes use of the parametric bootstrap method in order to infer a 95% confidence interval for nodal maximum power consumption per customer. This estimation is realized for a given node and a given month. Simulation results carried out on a real data set are presented and discussed.
Master of Science

The electric power policies in Nigeria and South Africa are considered the governments’ intention to provide quality and affordable electricity to the people. A comparative study on the electric power policies focuses on the similarities and differences in the policy approaches, the policy issues that affect electrification, and the impact of the policy issues in achieving the goal of universal access to quality and affordable electricity power in both countries. The methodological approach allows for an in depth textual study on the electric power policy documents in both countries. In Nigeria, the government intends to address the massive demand-supply imbalance and achieve the goal of electrification through reforms that focus on private sector-led growth in the sub-sector. In South Africa, the identification of electrification as a public problem by the post apartheid government leads to an integrated policy framework that focuses on balancing economic concerns with social and environmental considerations. The study identifies electricity provision as a social welfare responsibility of the governments in both countries and examines the policy issues in the context of public welfare. In Nigeria, the policy issues are found to be self serving and not in line with sustainable public interest, given the socio-economic challenges. As a result they, exert less impact on achieving the goal of universal access to quality and affordable electricity in the country. In South Africa, good governance in the sub-sector has enabled the identification of policy issues in line with sustainable public interests of social equity, poverty alleviation and environmental sustainability; and government using public administration agencies to play a key role in service delivery. Recommendations of the study mainly derive from the South African experience on electrification, and are intended to offer some policy-lessons to Nigeria in the sub-sector. The study contributes to new knowledge in the discipline of public administration by opening up new vistas for a comparative analysis of electric power policy issues in both countries in the context of public welfare. Besides, a comparative study on electrification in Nigeria and South Africa from a policy angle contributes to the existing knowledge base in the discipline.

CMOS is well known for its ability to scale. This fact is reflected in the aggressive scaling on a continual basis from the invention of CMOS up to date. As devices are scaled, device performance improves due to shorter channel lengths and more densely packed functions for the same amount of area. In recent years, however, the performance gain obtained through scaling has begun to suffer under the degradation of the associate interconnect performance. As devices become smaller, interconnects need to follow. Unlike transistors, the scaling of interconnects results in higher capacitances and resistances, thereby limiting overall system performance. Trying to alleviate the delay effects results in increased power consumption, especially in global structures such as clock distribution networks. A possible solution to this problem is the use of optical interconnects, which are fast and much less lossy than the electrical equivalents. This dissertation describes an investigation on what future technology nodes will entail in terms of power consumption of clock networks, and what is required for an optical alternative to become feasible. A common clock configuration is used as a basis for comparison, where both electrical and optical networks are designed to component level. Optimisation is done on both to ensure a reasonable comparison, and the results of the respective power consumption components are then compared in order to find the criteria for a feasible optical clock distribution scheme. Copyright
Dissertation (MEng)--University of Pretoria, 2009.
Electrical, Electronic and Computer Engineering
unrestricted

Installation and utilization of residential distribution transformers has not changed substantially over a long period of time. Utilities typically size their transformers based on a formula that takes into account broadly what types and how many dwellings will be connected. Most new residential dwellings feature 200 Amp service per household with an anticipated energy demand of under 20,000 kWh per year. Average electrical energy consumption varies from state to state but averages to 11,280 kWh per year. Energy demand is expected to fall into a typical residential load curve that shows increased demand early in the morning, then decreasing during the day and another peak early to late evening. Distribution transformers are sized at the limit of the combined evening peak with the assumption that the transformer has enough thermal mass to absorb short overloads that may occur when concurrent loading situations among multiple dwellings arise. The assumption that concurrent loading is of short duration and the transformer can cool off during the night time has been validated over the years and has become standard practice. This has worked well when dwelling loads follow an averaging scheme and low level of coincidence. With the arrival of electric vehicles (EV's) this assumption has to be reevaluated. The acquisition of an electric vehicle in a household can drive up energy demand by over 4000 kWh per year. Potentially problematic is the increased capacity of battery packs and the resulting proliferation of Level 2 chargers. The additional load of a single Level 2 charger concurring with the combined evening peak load will push even conservatively sized distribution transformers over their nameplate rating for a substantial amount of time. Additionally, unlike common household appliances of similar power requirements such as ovens or water heaters, a Level 2 battery charger will run at peak power consumption for several hours, and the current drawn by the EVs has very high levels of harmonic distortion. The excessive loading and harmonic profile can potentially result in damaging heat build-up resulting in asset degradation. In this thesis I present a device and method that monitors pole mounted distribution transformers for overheating, collect and wirelessly upload data and initiate commands to chargers to change output levels from Level 2 to Level 1 or shut down EV charging altogether until the transformer returns into safe operational range.

In the new global and local scenario, the advent of intelligent distribution networks or Smart Grids allows real-time collection of data on the operating status of the electricity grid. Based on this availability of data, it is feasible and convenient to predict consumption in the short term, from a few hours to a week. The hypothesis of the study is that the method used to present time variables to a prediction system of electricity consumption affects the results.

The interruption cost for one hour of a petrochemical plant is 33 times higher than that of the average interruption cost for industrial plants across all industries. In addition to the high cost of loss of production, interruptions to the operations of petrochemical and gas-toliquid plants pose safety and environmental hazards. Thus it is necessary to better understand the reliability requirements of petrochemical and gas-to-liquid plants. This study investigated the reliability of electrical distribution networks used in petrochemical and gas-to-liquid plants compared to those used in other industrial plants. A model was developed that can be used to establish the adequacy of the reliability of a distribution network in terms of the components and network topologies used. This model was validated against data that had been collected by the IEEE and applied to an actual petrochemical plant. Over 19 years’ worth of data regarding the trips that have occurred on the distribution network of an existing petrochemical plant was collected and manipulated in order to calculate the reliability indices associated with the equipment used to make up thisRecommended Practice for the Design of Reliable Industrial and Commercial Power Systems. The cost of loss of production and the capital costs associated with increased reliability were calculated for a section of the existing petrochemical plant. The reliability associated with different network topologies that could possibly be used to supply power to this section of the plant were modelled using an appropriate software package. The resulting total cost of ownership over the life of the plant associated with each topology was then calculated in order to establish which network topology is the most appropriate for petrochemical and gas-to-liquid plants. It was concluded the components that affect the reliability of an industrial distribution network are different to those that affect a utility distribution network. These components were listed and compared. It was found that the reliability indices that were calculated for the components that affect the reliability of a petrochemical plant were similar to those provided by the IEEE. 17 out of 20 of the indices that were calculated were within the required factor of deviation. Generally the failure rates of components used in petrochemical plants were very similar to those given in the IEEE Gold Book, while the MTTR’s for the components used in petrochemical plants were found to be slightly better than those given in the IEEE Gold Book. The effect of network topology was found to be significant, with small changes in the topology of a network resulting in large variations in the reliability of the network. It was also found that the most appropriate type of network topology to use in the design of the electrical distribution network of a petrochemical plant is the dual radial network. This is the most conservative of the commonly used network topologies and is the one that is currently used in the existing plant that was studied. Due to the high cost of loss of production in petrochemical plants it was established that any incremental improvement in the reliability of the dual radial network would be beneficial to the total cost of ownership of such a plant. Such incremental improvement of the reliability of the distribution network could be cost effectively achieved by adopting a conservative maintenance strategy and the establishment of a conservative spares inventory. Before this study was undertaken, there was no literature around the reliability of electrical distribution networks that focused specifically on petrochemical and gas-to-liquid plants. This study produced a set of reliability indices and a model that electrical engineers can use in the reliability analysis of petrochemical and gas-to-liquid plants. Furthermore it shows that, because the cost of loss of production in petrochemical plants is so high, the most conservative distribution network design and maintenance philosophies should always be used. distribution network. These reliability indices were compared to those given by the IEEE
Dissertation (MEng)--University of Pretoria, 2013.
gm2014
Electrical, Electronic and Computer Engineering
unrestricted

Останнім часом через ряд причин як технічних, так і економічних, втрати електроенергії в розподільчих мережах є досить істотними і це незважаючи на загальну тенденцію до зниження електроспоживання. Виходячи з цього, з’явилася нагальна потреба в формуванні моделі для розрахунку втрат електроенергії саме в розподільчих мережах.

The world is now in a transition towards a more sustainable future. Actions to reduce the green-house gases (GHG) emissions have been promoted and implemented globally, including switching to electric vehicles (EVs) and renewable energy technologies, such as solar photovoltaics (PV). This has led to a massive increase of EVs and PV adoption worldwide in the recent decade. However, large integration of EVs and PV in buildings and electricity distribution systems pose new challenges such as increased peak loads, power mismatch, component overloading, and voltage violations, etc. Improved synergy between EVs, PV and other building electricity load can overcome these challenges. Coordinated charging of EVs, or so-called EV smart charging, is believed to a promising solution to improve the synergy. This licentiate thesis investigates the synergy between residential EV charging and PV generation with the application of EV smart charging schemes. The investigation in this thesis was carried out on the individual building, community and distribution grid levels. Smart charging models with an objective to reduce the net-load (load - generation) variability in residential buildings were developed and simulated. Reducing the net-load variability implies both reducing the peak loads and increasing the self-consumption of local generation, which will also lead to improved power grid performance. Combined PV-EV grid hosting capacity was also assessed.       Results show that smart charging schemes could improve the PV self-consumption and reduce the peak loads in buildings with EVs and PV systems. The PV self-consumption could be increased up to 8.7% and the peak load could be reduced down to 50%. The limited improvement on self-consumption was due to low EV availability at homes during midday when the solar power peaks. Results also show that EV smart charging could improve the grid performance such as reduce the grid losses and voltage violation occurrences. The smart charging schemes improve the grid hosting capacity for EVs significantly and for PV slightly. It can also be concluded that there was a slight positive correlation between PV and EV hosting capacity in the case of residential electricity distribution grids.

Orientador: Moacyr Trindade de Oliveria Andrade
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-05T19:49:11Z (GMT). No. of bitstreams: 1 Vieiralves_EduardodeXerez_M.pdf: 1874956 bytes, checksum: 4f79bc70e42ae0c47e0a35cde1327ad1 (MD5) Previous issue date: 2005
Resumo: O equilíbrio econômico-financeiro garantido pelo contrato de concessão firmado pelas concessionárias junto ao poder concedente, tem como prerrogativa uma gestão atuante por parte do agente prestador do serviço, o que evidencia o seu controle técnico e comercial, bem como a promoção do desenvolvimento tecnológico dos serviços concedidos. Neste contexto, é de suma importância que a receita da concessionária, fruto de sua gestão na aquisição da energia a ser utilizada, bem como sua efetiva disponibilidade, seja dirigida ao mercado e aos consumidores com a qualidade requerida, a preços compatíveis com a renda média da população regional e com um percentual de perdas compatível com a tecnologia disponível. O controle das perdas técnicas e comerciais, em empresas do setor elétrico é fundamental para a consecução dos objetivos das concessionárias e da população a ser atendida. A falta de efetivo controle das perdas gera desperdício, ineficiência e redunda em custos elevados. Na região amazônica, as fontes energéticas são suportadas por parques térmicos que queimam material fóssil. Nessas condições o desperdício energético provoca, adicionalmente, danos desnecessários à natureza. As emissões de material particulado e de gases do efeito estufa, na condição de grandes perdas comerciais das empresas do setor elétrico, são mais elevadas, o que fatalmente vai agravar as condições ambientais da vida das gerações futuras. Na região Norte do Brasil, os sistemas elétricos isolados, em função do tipo das fontes energéticas e das grandes distâncias envolvidas, apresentam altos custos de operação e manutenção. As empresas apresentam índices de perdas elevadíssimos, que inviabilizam totalmente o negócio, razão pela qual, até hoje, vários são os mecanismos de subsídios associados ao mesmo, visando a viabilização do serviço de energia elétrica. O presente trabalho visa analisar a situação das perdas comerciais na região, dando ênfase ao ¿Caso Manaus¿, procurando identificar as suas causas e efeitos, tanto para a sociedade em geral como para os empresários do setor. Mais especificamente, se abordará o estudo de caso da empresa Manaus Energia S/A, por ser a maior dos sistemas isolados e por apresentar índices de perdas muito acima do admissível e da média das concessionárias do Setor Elétrico Nacional
Abstract: The financial-economical equilibrium guaranteed by the concession contract made by the concessionaries before the granting power, has as a prerogative an acting management by the service agent owner. That evidences its technical and commercial control, as well as the promotion of the technological development of the granted services. In such a context, it is of great importance that the concessionary receipt, product of its management in the acquisition of the energy to be used, as well as in its effective availability, be driven towards the market and the consumers with the quality requested with compatible prices at the middle income of the local population and with a loss percentage balanced to the technology available. The control of such technical and commercial loss in the companies of the electric field is fundamental to the accomplishment of the concessionary objectives and to the population attending.The lack of an effective control about the loss generates waste, non-efficiency and leads to elevated costs. In the Amazon area, the energetic sources are supported by thermic park which burn fossil matter. Besides, in such conditions the energetic waste provokes unnecessary waste to the nature. The emissions of particled material and gases from the greenhouse effect, in the condition of great commercial losses of the electric field companies are higher what will worsen the environmental conditions of the future generations life. In Brazil north region, the isolated electric systems due to the kind of the energetic sources and the great distances involved, lead to high costs of operation and maintenance. The companies show very high losses rates which make the business completely unfeasible, that is the reason, nowadays, due to many are the resources of subsidies associated attempting the availability of the electric energy service. The present work aims to analyze the state of the commercial losses in the region, emphasizing ¿Manaus case¿, searching the causes and effects identification, to the society in general, as to the sector entrepreneurs. More specifically, there will be approached the case study of Manaus Energia S/A company, for being the biggest of the isolated systems and for presenting a loss rate much higher from the admissible and the average of the National Electric Sector concessionaries
Mestrado
Energia Eletrica
Mestre em Engenharia Mecânica

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.14.02 – електричні станції, мережі і системи – Національний технічний університет України "Київський політехнічний інститут імені Ігоря Сікорського", Київ, 2018. Дисертація присвячена науково-прикладній проблемі – пошуку винуватців гармонічних спотворень в електричних мережах та підвищенню якості електроенергії шляхом створення системи діагностики і контролю на базі АСКОЕ. Обґрунтовано використання технології розподілених вимірювань для пошуку винуватців спотворень. Розроблено модифікацію методу гармонічного аналізу для підвищення достовірності визначення джерел спотворення. На підставі результатів досліджень запропоновано методи розподілу компенсаційних виплат між елементами електричної мережі та абонентами, що споживають потужність вищих гармонік. Розроблено ряд рекомендацій щодо практичного застосування результатів дисертаційної роботи. Запропоновано метод непрямого контролю температури кабельних ліній.
Thesis for the PhD degree in technical sciences, Specialty 05.14.02 – power plants and electric power complexes. National technical university of Ukraine "Kyiv polytechnic institute", Kyiv, 2019. The thesis is oriented to the scientific and applied problem - harmonic distortion sources detection in distribution systems (DS), improving the electromagnetic compatibility of electrical equipment, increasing the reliability of electric power supply by creating a diagnostic and control system. The use of distributed measurements to distortions source detection is justified. A modification of the method of harmonic analysis is developed to increase the reliability of distortions sources detection. Based on the study’s results, methods for distributing compensation payments between DS`s subjects that consume harmonics power are proposed. A number of recommendations on the practical application of the results of the thesis work have been developed. A method for indirect monitoring of the temperature of cable lines is proposed.

Abstract The objective of this thesis was to obtain new information about mechanisms of thermomechanical pulp refining in the inner area of a refiner disc gap by studying inter-fibre refining and by calculating the distribution of energy consumption in the refiner disc gap. The energy consumption of thermomechanical pulping process is very high although theoretically a small amount of energy is needed to create new fibre surfaces. Mechanisms of refining have been widely studied in order to understand the high energy consumption of the process, however, phenomena in the inner area of disc gap has had less attention. It is likely that this important position is causing high energy consumption due to the high residence time of pulp located there. The power distribution as a function of the refiner disc gap was calculated in this work. The calculation was based on mass and energy balances, as well as temperature and consistency profiles determined by mill trials. The power distribution was found to be dependent on segment geometry and the refining stage. However, in the first stage refiner with standard refiner segments, a notable amount of power was consumed in the inner area of the disc gap. Fibre-to-fibre refining is likely to be the most important mechanism in the inner area of disc gap from the point of view of energy consumption. In this work the inter-fibre refining was studied using equipment for shear and compression. Fibre-to-fibre refining was found to be an effective way to refine fibres from coarse pulp to separated, fibrillated and peeled fibres if frictional forces inside the compressed pulp were high enough. It was proposed that high energy of today’s thermomechanical pulping process could derive from too low frictional forces that heated pulp and evaporated water without any changes in fibre structure. The method to calculate power distribution and results of fibre-to-fibre refining experiments may give ideas for developing today’s thermomechanical pulp refiners’ or for developing totally new energy saving mechanical pulping processes.

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.14.02 – електричні станції, мережі і системи – Національний технічний університет України "Київський політехнічний інститут імені Ігоря Сікорського", Київ, 2018. Дисертація присвячена науково-прикладній проблемі – пошуку винуватців гармонічних спотворень в електричних мережах та підвищенню якості електроенергії шляхом створення системи діагностики і контролю на базі АСКОЕ. Обґрунтовано використання технології розподілених вимірювань для пошуку винуватців спотворень. Розроблено модифікацію методу гармонічного аналізу для підвищення достовірності визначення джерел спотворення. На підставі результатів досліджень запропоновано методи розподілу компенсаційних виплат між елементами електричної мережі та абонентами, що споживають потужність вищих гармонік. Розроблено ряд рекомендацій щодо практичного застосування результатів дисертаційної роботи. Запропоновано метод непрямого контролю температури кабельних ліній.
Thesis for the PhD degree in technical sciences, Specialty 05.14.02 – power plants and electric power complexes. National technical university of Ukraine "Kyiv polytechnic institute", Kyiv, 2019. The thesis is oriented to the scientific and applied problem - harmonic distortion sources detection in distribution systems (DS), improving the electromagnetic compatibility of electrical equipment, increasing the reliability of electric power supply by creating a diagnostic and control system. The use of distributed measurements to distortions source detection is justified. A modification of the method of harmonic analysis is developed to increase the reliability of distortions sources detection. Based on the study’s results, methods for distributing compensation payments between DS`s subjects that consume harmonics power are proposed. A number of recommendations on the practical application of the results of the thesis work have been developed. A method for indirect monitoring of the temperature of cable lines is proposed.

Submitted by Maria Aparecida (cidazen@gmail.com) on 2017-04-17T13:14:17Z No. of bitstreams: 1 Elson Moreira.pdf: 7883984 bytes, checksum: cf59b3b0b24a249a7fd9e2390b7f16de (MD5)
Made available in DSpace on 2017-04-17T13:14:17Z (GMT). No. of bitstreams: 1 Elson Moreira.pdf: 7883984 bytes, checksum: cf59b3b0b24a249a7fd9e2390b7f16de (MD5) Previous issue date: 2017-02-10
CNPQ
A problem of electric power quality that always affects the consumers of the distribution network are the harmonic distortions. Harmonic distortions arise from the presence of socalled harmonic sources, which are nonlinear equipment, i.e., equipment in which the voltage waveform differs from the current. Such equipment injects harmonic currents in the network generating distortions in the voltage waveform. Nowadays, the number of these equipment in the electrical network has increased considerably. However, the increasing use of such equipment over the network makes systems more vulnerable and prone to quality problems in the supply of electricity to consumers. In addition, it is important to note that in the current scenario, the generation of electricity from renewable sources, connected in the secondary distribution network, is increasing rapidly. This is mainly due to shortage and high costs of fossil fuels. In this context, the Photovoltaic Distributed Generation (PVDG), that uses the sun as a primary source for electric energy generation, is the main technology of renewable generation installed in distribution network. However, the PVDG is a potential source of harmonics, because the interface of the PVDG with the CA network is carried out by a CC/CA inverter, that is a highly nonlinear equipment. Thus, the electrical power quality problems associated with harmonic distortion in distribution networks tend to increase and be very frequent. One of the main indicators of harmonic distortion is the total harmonic distortion of voltage ( ) used by distribution utilities to limit the levels of harmonic distortion present in the electrical network. In the literature there are several deterministic techniques to estimate . These techniques have the disadvantage of not considering the uncertainties present in the electric network, such as: change in the network configuration, load variation, intermittence of the power injected by renewable distributed generation. Therefore, in order to provide a more accurate assessment of the harmonic distortions, this dissertation has as main objective to develop a probabilistic methodology to estimate the level of in secondary distribution networks considering the uncertainties present in the network and PVDG connected along the network. The methodology proposed in this dissertation is based on the combination of the following techniques: three-phase harmonic power flow in phase coordinate via method sum of admittance, point estimate method and series expansion of Gram-Charlier. The validation of the methodology was performed using the Monte Carlo Simulation. The methodology was tested in European secondary distribution network with 906 nodes of 416 V. The results were obtained by performing two case studies: without the presence of PVDG and with the PVDG connection. For the case studies, the following statistics for nodal were estimated: mean value, standard deviation and the 95% percentile. The results showed that the probabilistic estimation of is more complete, since it shows the variation of due to the uncertainties associated with harmonic sources and electric network. In addition, they show that the connection of PV-DG in the electric network significantly affects the levels of of the electric network.
Um problema de qualidade de energia elétrica que afeta os consumidores da rede de distribuição secundária são as distorções harmônicas. As distorções harmônicas são provenientes da presença das chamadas fontes de harmônicas que são equipamentos de características não-lineares, ou seja, equipamentos em que a forma de onda da tensão difere da de corrente. Tais equipamentos injetam correntes harmônicas na rede produzindo, portanto distorções na forma de onda da tensão. Nos dias atuais, a quantidade desses equipamentos na rede elétrica tem aumentado consideravelmente. Porém, o uso crescente desse tipo de equipamento ao longo da rede torna os sistemas mais vulneráveis e propensos a apresentarem problemas de qualidade no fornecimento de energia elétrica aos consumidores. Além disso, é importante destacar que no cenário atual, a geração de energia elétrica a partir de fontes renováveis, conectada na rede de distribuição secundária, está aumentando rapidamente. Isso se deve principalmente devido a escassez e altos custos dos combustíveis fosseis. Neste contexto, a Geração Distribuída Fotovoltaica (GDFV), que utiliza o sol como fonte primária para geração de energia elétrica, é a principal tecnologia de geração renovável instalada na rede de distribuição no Brasil. Contudo, a GDFV é uma potencial fonte de harmônica, pois a interface da GDFV com a rede CA é realizada por um inversor CC/CA, que é um equipamento altamente não-linear. Desde modo, os problemas de qualidade de energia elétrica associados à distorção harmônica nas redes de distribuição tendem a aumentar e a serem bem frequentes nos consumidores da rede de distribuição secundárias. Um dos principais indicadores de distorção harmônica é a distorção harmônica total de tensão ( do inglês “Total Harmonic Distortion of Voltage”) utilizada pelas concessionárias de energia elétrica para quantificar os níveis de distorção harmônica presentes na rede elétrica. Na literatura técnica existem várias técnicas determinísticas para estimar a . Essas técnicas possuem a desvantagem de não considerar as incertezas presentes na rede elétrica, tais como: mudança na configuração da rede, variação de carga e intermitência da potência injetada pela geração distribuída renovável. Portanto, a fim de fornecer uma avaliação mais precisa das distorções harmônicas, este trabalho tem como principal objetivo desenvolver uma metodologia probabilística para estimar o nível de em redes de distribuição secundária considerando as incertezas presentes na rede e na GDFV conectada ao longo da rede. A metodologia proposta nesta dissertação se baseia na combinação das seguintes técnicas: fluxo de potência harmônico trifásico em coordenadas de fase via método de soma de admitância, método de estimação por pontos e expansão em série de Gram-Charlier. Além disso, a validação da metodologia foi realizada utilizando a Simulação Monte Carlo. A metodologia desenvolvida foi testada na rede de distribuição secundária europeia com 906 nós de 416 V. Os resultados foram obtidos realizando dois casos de estudos: sem a presença de GDFV e com a conexão de GDFV. Para ambos os casos de estudo as seguintes estatísticas do nodal foram estimadas: valor médio, desvio padrão e o percentil de 95%. Os resultados demonstraram que a estimação probabilística da é mais completa, pois mostra a variação da devido às incertezas associadas com as fontes de harmônicas e as da rede elétrica. Os resultados também mostram que a conexão da GDFV afeta significativamente os níveis de da rede elétrica

Le discours publicitaire d’aujourd’hui ne se limite plus seulement à une description technique des produits, mais participe aussi à la construction de systèmes de valeurs selon une logique de calage qui consiste à se mettre au diapason des courants sociaux et des aspirations des individus. L’apparition de comportements de consommation inédits oblige les marques à renouveler leurs stratégies de communication, quitte à faire évoluer le rôle social de la publicité. Au milieu des années quatre-vingt, la marque Benetton s’illustre en proposant une vision politique de la consommation soutenue par un discours publicitaire qui ne vante plus les qualités du produit ni ne fait appel à la dimension hédonique de la consommation. Au contraire, il se réfère à des événements d’actualité traités ordinairement par le discours médiatique et s’adresse à des citoyens-consommateurs. D’autres acteurs économiques s’inscrivent depuis dans cette tendance. À partir d’une analyse sémiotique des publicités de l’enseigne E. Leclerc, l’objectif de cette recherche est de mettre en évidence l’existence d’un discours publicitaire particulier qui n’est plus conventionnel à partir du moment où il convoque une dimension politique. Affichant une posture militante sur la question écologique ou celle du pouvoir d’achat, l’enseigne transgresse les codes du discours publicitaire pour revendiquer un engagement citoyen. Les résultats d’analyse montrent par ailleurs que l’installation d’un champ discursif relativement éloigné de la fonction commerciale de l’enseigne témoigne de l’évolution de la société postmoderne à laisser la gestion de l’intérêt général aux entreprises privées, au détriment de l’action publique
Advertising discourse today is no longer limited to only a technical description of products, but also participates in the construction of values. In that way it is attuned to social currents and aspirations of individuals. The emergence of new consumer behaviors requires brands to renew their communication strategies, even to change the social role of advertising. In the mid-eighties, the Benetton brand proposed a political vision of consumption supported by advertising discourse that no longer boasts the qualities of the product or does not use the hedonic dimension of consumption. Rather, it refers to current events usually treated by the media discourse, and is intended for citizens and consumers. Since then other economic actors follow this approach. From a semiotic analysis of advertisements of E. Leclerc, the objective of this research is to demonstrate the existence of a particular advertising discourse which is no longer conventional since it carries a political dimension. Featuring a militant stance on ecological matters or purchasing power, the brand transgresses the codes of advertising discourse to claim a civic engagement. The analysis results also show that the emergence of a field which is relatively distant from the commercial function of the brand reflects the evolution of postmodern society to leave the management of the general interest to private companies, to detriment of public action

Este trabalho estuda o impacto energético da otimização do tamanho do payload de códigos convolucionais em um enlace sem fio ponto-a-ponto dentro de uma rede de sensores. Consideram-se dois modelos de canal, AWGN e Rayleigh, visando representar cenários com diferentes características quanto à severidade de enlace. Nesse contexto, faz-se o estudo da otimização da relação sinal-ruído, da taxa de código empregada, bem como a otimização do tamanho do payload para diferentes condições de transmissão. Os dados numéricos obtidos através de simulação demonstram que existe um ponto ótimo para o tamanho do payload, que varia com a distância de transmissão e que proporciona ganhos em termos de eficiência energética, especialmente em enlaces de curta distância.
This paper studies the impact of the payload size in the energy efficiency in a point-to-point link in a wireless sensor network using convolutional codes. Two channel models are considered, AWGN and Rayleigh, representing distinct conditions with respect to the severity of the link. In this context, signal-to-noise ratio, code rate and payload size are optimized. The numeric results obtained through simulations show that there is an optimal point for the payload size, which depends on the transmission distance, and which provides gains in the overall energy efficiency, especially in short range links.

This study of contemporary jazz discourse and gender applies the techniques of critical discourse analysis, inspired by M.A.K. Halliday's systemic functional linguistics and Norman Fairclough's qualitative critical discourse analysis, to explicate the unequal distribution of power in society as represented by the institutions of jazz and mass media, in discourse about jazz vocal artists. Specifically, the study focuses on the way the genres of jazz CD review, jazz performance review, and interviews with jazz artists – disseminated via the institutions JazzTimes and Live New Orleans – represent the artists' identities, roles, achievements and skills. Following Norman Fairclough and the feminist scholar Mary Talbot, the study assumes that institutions of mass media not only discursively construct the gender of jazz vocal artists, but also represent the performers' achievement and skills from a hegemonic standpoint, reflecting the commonsense assumptions about women and men and their roles in patriarchal society.

Este trabalho estuda as potenciais melhorias na eficiência energética e vazão do método híbrido de requisição automática de retransmissão (Hybrid Automatic Retransmission Request, HARQ). A análise inclui as camadas física (PHY) e de acesso ao meio (MAC). É investigada a relação de compromisso gerada pelo HARQ, o qual demanda uma menor potência de transmissão para uma certa probabilidade de falha alvo ao custo de mais acessos ao canal. Uma vez que a competição para acesso ao canal na camada MAC é bastante custosa em termos de energia e atraso, os resultados mostram que a utilização do HARQ leva a uma grande melhoria de performance devido ao menor número de nós competidores – uma consequência da redução na potência de transmissão necessária. Contra-intuitivamente, esta análise leva à conclusão que retransmissões podem diminuir o atraso, melhorando a performance do sistema. Finalmente, são também investigados valores ótimos para o número de retransmissões permitidas, visando maximizar vazão ou/e eficiência energética.
This work studies the potential improvements in terms of energy efficiency and throughput of a hybrid automatic retransmission request (HARQ) mechanism. The analysis includes both the physical (PHY) and medium access (MAC) layers. We investigate the trade-off provided by HARQ, which demands reduced transmit power for a given target outage probability at the cost of more accesses to the channel. Since the competition for channel access at the MAC layer is very expensive in terms of energy and delay, our results show that HARQ leads to great performance improvements due to the decrease in the number of contending nodes – a consequence of the reduced required transmit power. Counter-intuitively, our analysis leads to the conclusion that retransmissions may decrease the delay, improving the system performance. Finally, we investigate the optimum values for the number of allowed retransmissions in order to maximize either the throughput or the energy efficiency.

L'économie d'énergie dans les réseaux de télécommunication est un objectif majeur pour réduire la consommation globale. La part du domaine IT est déjà très élevée et tend à augmenter. En effet, de nombreuses techniques pour réduire la consommation dans d'autres industries ou services se traduit par plus de traitements informatiques et de télécommunications (l'approche ”Green by IT”) et donc par une augmentation de la consommation dans les domaines IT. Il est donc important d'un point de vue économique d'arriver à réduire la consommation énergétique par bit transmis ou calculé (l'approche ”Green IT” qui est au centre de notre approche). Dans le domaine des réseaux, l'optimisation énergétique repose principalement sur une adaptation de l'architecture et des ressources employées en fonction des flux à transporter et de la qualité de service promise. On cherche donc à adapter les ressources à la demande, ce qui se traduit par un dimensionnement dynamique et adapté à la charge. Ceci est par nature différent d'un dimensionnement au pire cas que l'on utilise généralement. Sur le plan technologique, cela nécessite que les équipements de réseaux disposent de modes ”sleep”,”deep sleep” ou ”hibernate” (terminologie variant selon les fournisseurs)mais qui sont tous associés au même concept: mettre en sommeil l'équipement pour réduire sa consommation d'énergie. Pour que le compromis performance/énergie soit pertinent, il parait important d'utiliser des formules de consommation énergétiques obtenues à partir de l'utilisation des ressources du réseau. Les méthodes que nous proposons relèvent de la théorie des réseaux de files d'attente, l'analyse des chaines de Markov (analytiquement en proposant de nouvelles formes produitet numériquement en suggérant de nouveaux algorithmes de résolution) et la théorie de la comparaison stochastique. Au niveau applicatif nous avons traité différentes problématiques: les mécanismes de DVFS avec un changement de vitesse des processeurs, la migration de tâche entre serveurs physique dans un centre de données (équilibre de charge, consolidation), les réseaux optique avec un remplissage efficace des conteneurs optiques, la distribution d'énergie intermittente dans un réseau de capteurs (et réseau LORA) notamment en proposant un nouveau modèle des réseaux à paquet d'énergie (EPNs)
Energy saving in telecommunication networks is a major objective to reduce overall consumption. The IT sector already has a very high contribution to this increase. Indeed, many techniques to reduce consumption in other industries or services results in more IT and telecommunications (the "Green by IT" approach) and therefore in an increase of consumption in IT domains. It is therefore important from an economical point of view to reduce the energy consumption per transmitted or calculated bit (the "Green IT" concept). In the networks domain, energy optimization is mainly based on an adaptation of the architecture and the resources employed according to the traffic flows to be transported and the promised quality of service. We therefore seek to adapt resources to demand, which results in a dynamic dimensioning adapted to the load. This is by nature different from the worst-case dimensioning commonly used. In terms of technology, this requires network equipment to have "sleep", "deep sleep" or "hibernate" modes (terminology varies among suppliers), but all of these modes are associated with the same concept: putting the equipment to sleep to reduce its energy consumption. For the performance/energy trade-off to be relevant, it seems important to use energy consumption formulas obtained from the network resource utilization. The approaches we propose are based on the theory of queuing networks, Markov chain analysis (analytically by proposing new product forms and numerically by suggesting new resolution algorithms) and the theory of stochastic comparison.At the application level we have addressed various issues: DVFS mechanisms with a change of processors speed, task migration between physical servers in a data center (load balancing, consolidation), optical networks with efficient filling of optical containers, intermittent power distribution in a sensor network (and LoRa network) including a new model of Energy Packet Networks (EPNs)

Made available in DSpace on 2017-07-10T16:41:32Z (GMT). No. of bitstreams: 1 Dissertacao Altamira Queiroz2.pdf: 2299194 bytes, checksum: 07ecb127ebc11ad21a0cb551e23c2f1b (MD5) Previous issue date: 2016-02-19
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
One of the main problems currently faced by electric utilities is the occurrence of energy losses in the distribution network caused by fraud and electricity theft. Because of the financial losses and risks to public safety, the development of solutions to detect and combat fraud in the distribution networks is of the utmost importance. This work presents an analysis of computational intelligence algorithms to extract knowledge in databases with information from monthly energy consumption to identify consumption patterns with anomalies which could represent fraud. The algorithms Artificial Neural Networks and Support Vector Machines were tested to see which one perform better on the identification consumption patterns with abnormalities. Tests have shown that the algorithms used are able to detect patterns in electricity consumption curves, including special situations of fraud that manual techniques did not detect.
Um dos principais problemas que enfrentam atualmente as empresas concessionárias de energia elétrica é a ocorrência de perdas de energia na rede de distribuição, causadas por fraudes e furtos de energia elétrica. Sendo que tais problemas provocam prejuízos financeiros e também colocam em risco a segurança pública, é de grande interesse das concessionárias encontrar soluções para detectar e combater fraudes nas redes de distribuição de energia elétrica. Neste conceito, o presente trabalho apresenta uma análise dos algoritmos de Inteligência Computacional para extrair conhecimento de bases de dados de informações de consumo mensal de energia elétricas de usuários de uma determinada concessionária, a fim de identificar padrões de consumo com anomalias que representem possíveis fraudes nas redes de distribuição de energia elétrica. Para detectar padrões nas curvas de consumo, foram utilizados algoritmos de Redes Neurais Artificiais e Máquinas de Vetores de Suporte. Após a criação dos modelos, estes foram testados para verificar qual seria o melhor algoritmo para a detecção de padrões de consumo com anomalias, e os resultados obtidos, foram então, comparados com uma base de dados fornecida pela concessionária com a verificação manual dos usuários. Os testes demonstraram que os algoritmos utilizados são capazes de detectar padrões nas curvas de consumo de energia elétrica, inclusive detectando situações especiais de fraudes que técnicas manuais não detectaram.

博士
國立交通大學
電子工程系所
92
As the semiconductor technology getting advances, the density of the devices and the metal lines are growing too large to keep the heat conduction problem unnoticed. Furthermore, the heat generated by the circuits is boosted with the ramping of the operating speed. Improperly heat conduction can lead to the smoking of the chip, torturing or breaking of the metal lines, or shifting of the performance. All these problems can be prevented by the power consumption estimation and optimization before taping out the chip. There are many ways of estimating power corresponding to different purposes. For example, we need to estimate energy consumption for battery endurance, we need the power consumption for temperature analysis, and we need the average current for wire width design, and the current density for reliability analysis. Although these measurements are all clearly defined, but they have a common problem that they are input signal dependent. To do the power analysis without lost of generality, we propose an automatic power profiler which is integrated into the most accurate circuit simulator - SPICE. With the power profiler, users can get a visual figure of the power consumption distribution instead of numbers with uncertainties. In this dissertation, we first analyze the relation between input statistics and the power consumption of the integrated circuits. The power sensitivities of inputs are proven to be effective provided the nominal points are selected properly. With this acknowledge, the power sensitivity sum of each input can be used to indicate the power consumption tendency of the input vectors, and to stratify the input vectors with. After the stratification, the sample variance can be reduced when simulating the input vectors selective. In addition, we found that stratification with power sensitivity can prevent the pre-matured estimation when estimating the average power consumption with Monte Carlo method. We also proposed a new way of stratification that is suitable for stratifying infinite length input sequences based on POST and POSTIV. By putting these findings together, we have modified the SPICE circuit simulator to be a tool that can visualize the distribution of the power consumption according to the user specified input statistics or input sequences.

碩士
國立臺灣科技大學
電子工程系
100
With the explosive growth of data processing capacity demand, the multi-core processor architecture has been applied to increase the efficiency and capability of computing. Consequently, it results a considerable difference on the average power consumption and temperature curve comparing to single core processor. However, while emphasizing on enhancing the efficiency of processor and meeting the consumer electronics trend of lighter weight and slim size, how to lower power consumption with temperature control and increasing the processor computing capability becomes the key technology. In a computer system, the processor usually consumes the largest proportion of power among the whole system. It draws the researchers and product developers’ attention to the processors’ power consumption under different operation modes. In this paper, we proposed a multi-core processor power measurement system; two topics have been studied: (1) the comparison of power consumption under the same test programs (Benchmark) between different number of executing cores, and the relationship of executing core numbers and total power consumption; (2) the effect of Intel Turbo Boost technology on power consumption and CPU performance. Two important findings are derived from the experiments. First, according to the results of executing the same program with different number of cores, the multi-core systems can save 10% power consumption with 10% performance improvement compared to the single core system in the light-loading mode. Moreover, when the system is in the heavy-loading mode, multi-core processors can save 75% power consumption and have a 95% performance improvement in comparing to single core processor. Second, when Intel Turbo Boost technology is activated, the power consumption increases about 10% with the efficiency increased more than 9%. However, when the system is in the heavy-loading state, Turbo Boost increases the power consumption about 1% without significant improvement in performance. In addition, the experiments indicate that the temperature on each processor core also decreases with the increment of active core numbers. This study demonstrated that increasing the number of processor cores can effectively reduce the total power consumption of the system and improve the performance. Therefore, system designers may have further studies on multi-core processing architecture to explore how to improve system performance and save more power consumption in the light-loading condition.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in ful lment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 2015
The work presented extends and contributes to research in Non-Intrusive Load Monitoring (NILM), focussing on steady-state and transient power measurement disaggregation techniques for circuits containing household ap- pliances. Although previous work in this area has produced and evaluated a wide range of NILM approaches, much of it has involved the use of datasets captured from real-world household implementations. In such cases, the lack of accurate ground truth data makes it di cult to assess disaggregation tech- niques. In the research presented, three NILM techniques are comparatively evaluated using measurements from typical household appliances assembled within a laboratory environment, where accurate ground truth data could be compiled to complement the measurements. This allows for the accu- racy of the various disaggregation approaches to be precisely evaluated. It is demonstrated that the correlation of transient event edges in aggregated power measurements to individual appliance transient exemplars performs better than the matching of steady-state power levels against individual ap- pliance state combinations. Furthermore, the transient approach is shown to be the most appropriate technique for further development.
MT2017

碩士
國立臺北商業技術學院
商學研究所
101
Product quality plays the key role of the market dominance of an enterprise. All enterprises put great amount of resources into quality control activities to enhance their competitiveness. As the product quality of Taiwan Power Company , the electricity, is greatly related to the product quality of all enterprises, we explored in this study the qualitative determinants of Taiwan Power Company distribution lines by Total Quality Management methods. According to the study, the determinants include the support of policymakers, the soundness of the management system of contractors, the soundness of the management system of customer relationships, the soundness of the quality feedback system, and the soundness of the management system of service processes. Taipower are suggested to invest their limited resources on these 5 determinants to enhance their total service quality and meet customers’ needs. This study covers the distribution line maintenance departments of Taipower’s district offices across the country. We sent totally 210 questionnaires, and among the 175 responses, 153 were valid. We ran the confirmatory factor analysis to recognize the scale with reliability and validity, then we used regression analysis to verify the hypothesis. Our research results confirmed that the qualitative determinants of Taipower’s distribution line are the support of policymakers, the soundness of the management system of contractors, the soundness of the management system of customer relationships, the soundness of the quality feedback system, and the soundness of the management system of service processes; all these determinants have significant positive effects to the quality of Taipower’s distribution system. Accordingly, we proposed the management implications and specific recommendations as references for practical applications and follow-up studies.

M.Ing.
In a country that ranks forty seventh on a list of fifty countries in a world competitive survey economic growth should be a high priority in South Africa. The main player in South Africa's energy industry took up the gauntlet and is moving to economic growth with the vision 'to provide the world's cheapest electricity for growth and prosperity." Competition was introduced among the electricity producers by a process called trading and brokering. Majuba power station, the most expensive electricity producer on the South African grid, was left out in the cold. Management of Majuba is challenged to derive resourceful strategies to ensure sustained profitability. These strategies will require a study into world trends to enable them to be more competitive. Crystal ball gazing is not needed to know that major restrictions on pollution of the atmosphere by industry will be curbed by stringent legislation. The current electrification programme in South Africa is bound to impact the shape of the daily load curve. Labour cost and the rate of inflation have been increasing and can be expected to keep on rising in the foreseeable future. It is important to know what macro effect these factors will have on the South African power industry. Majuba must be able to identify the changes lurking on the horizon and have contingency plans in place to meet these challenges. In this work different types of plant needed to meet the daily load demand are researched from literature. It is then compared to the types of plant installed in South Africa. This leads to the conclusion that the installed plant in South Africa is not sufficient to meet the daily demand effectively. A case study is done on Majuba Power Station that has been operating in a two shifting mode since December 1996. This means that the units is started every day to be on full load in time for morning peak and then shut down after evening peak. It is also shown that this mode of operation is proffitable for a relatively expensive power generator.

MSc (Statistics)
Department of Statistics
Short-term load forecasting in South Africa using machine learning and statistical models is discussed in this study. The research is focused on carrying out a comparative analysis in forecasting hourly electricity demand. This study was carried out using South Africa’s aggregated hourly load data from Eskom. The comparison is carried out in this study using support vector regression (SVR), stochastic gradient boosting (SGB), artificial neural networks (NN) with generalized additive model (GAM) as a benchmark model in forecasting hourly electricity demand. In both modelling frameworks, variable selection is done using least absolute shrinkage and selection operator (Lasso). The SGB model yielded the least root mean square error (RMSE), mean absolute error (MAE) and mean absolute percentage error (MAPE) on testing data. SGB model also yielded the least RMSE, MAE and MAPE on training data. Forecast combination of the models’ forecasts is done using convex combination and quantile regres- sion averaging (QRA). The QRA was found to be the best forecast combination model ibased on the RMSE, MAE and MAPE.
NRF

MSc (Statistics)
Department of Statistics
Forecasting of electricity peak demand levels is important for decision makers in Eskom. The overall objective of this study was to develop medium term load forecasting models which will help decision makers in Eskom for planning of the operations of the utility company. The frequency table of hourly daily demands was carried out and the results show that most peak loads occur at hours 19:00 and 20:00, over the period 2009 to 2013. The study used generalised additive models with and without tensor product interactions to forecast electricity demand at 19:00 and 20:00 including daily peak electricity demand. Least absolute shrinkage and selection operator (Lasso) and Lasso via hierarchical interactions were used for variable selection to increase the model interpretability by eliminating irrelevant variables that are not associated with the response variable, this way also over tting is reduced. The parameters of the developed models were estimated using restricted maximum likelihood and penalized regression. The best models were selected based on smallest values of the Akaike information criterion (AIC), Bayesian information criterion (BIC) and Generalized cross validation (GCV) along with the highest Adjusted R2. Forecasts from best models with and without tensor product interactions were evaluated using mean absolute percentage error (MAPE), mean absolute error (MAE) and root mean square error (RMSE). Operational forecasting was proposed to forecast the demand at hour 19:00 with unknown predictor variables. Empirical results from this study show that modelling hours individually during the peak period results in more accurate peak forecasts compared to forecasting daily peak electricity demand. The performance of the proposed models for hour 19:00 were compared and the generalized additive model with tensor product interactions was found to be the best tting model.
NRF