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Energy use in buildings and design requirements. The energy costs and financial costs of building materials, structures and space heating, the detailed patterns of use of heating systems in dwellings, and their interactions: their implications for design.Sansam, Robert Verdon January 1981 (has links)
The primary energy costs of building materials and structures
are discussed and comparisons are made between typical dwelling
types.
The economics of alternative wall, roof and floor constructions,
providing various levels of insulationy are examined. Costs are
assessed for a number of periods from 1970 to early 1980 for
heating by gas and night rate electricity. The effect of price
changes-on the economic attractiveness of insulation is
investigated and the likely effects of future price rises are
considered. It is concluded that, in certain circumstances,
higher levels of insulation than those normally used in the UK
have been economically attractive for the last few years and may
possibly become more so.
A survey of over fifty local authority houses with central
heating, carried out by the author in Spring 1978, is described.
Three types of houses of similar size were involved, having
gas-fired 'wet' systems, and ducted warm air heating from
electric storage and gas-fired units respectively. The survey
was designed to determine certain aspects of occupant behaviour
relevant to fuel consumption. Using regression techniques,
relationships are obtained which explain more than two thirds of
the variance of mean useful energy input rate between the houses
of a given type in cold weather in terms of hours of use of central
heating window opening habits, and for warm air heating, the
closing of outlet registers. It was also revealed that for the
house types with gas-fired heating the number of hours of use of
the central heating was strongly influenced by household size
and occupancy patterns.
The implications for building design of the effects of occupant
behaviour and of financial and energy costs are discussed.
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Inferential Latent Variable Models for Combustion ProcessesCardin, Marlene 01 1900 (has links)
This thesis investigates the application of latent variable methods to three combustion
processes. Multivariate analysis of flame images and process data is performed to predict
important quality parameters and monitor flame stability. The motivation behind this work is to decrease operational costs and greenhouse gases in these energy intensive processes. The three combustion processes studied are a lime kiln, a basic oxygen furnace and a coal-fired boiler. In lime kiln operation, the main goal is to stabilize final product temperature in order to reduce fouling and energy costs. Due to long process dynamics, prediction of product temperature is required at least one hour in advance for potential use in a control scheme. Several methods for extracting features from flame images were investigated for the prediction of the temperature. The best method is then combined with process data in a PLS
model that also incorporates dynamic information. The analysis revealed that prediction one hour into the future is successful using latent variable methods. In the basic oxygen furnace analysis, the main goal is to predict end-point carbon of the batch process. Termination of the batch as soon as the desired carbon is attained reduces oxygen consumption and thus operational cost. Traditional image analysis is used to identify a constant field of view in the flame images. Multivariate image feature extraction methods were then used in combination with process data to successfully predict the final carbon
content of the heat. The coal-fired boiler analysis focuses on monitoring of flame stability at different production and air to fuel levels of the boiler. Prediction of energy efficiency and off-gas chemistry from flame images is also investigated. An unexpected result was the ability to use the installed cameras for localized fouling monitoring. This thesis showed that the use of multivariate analysis of flame images and process data in combustion process is very promising. / Thesis / Master of Applied Science (MASc)
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The energy system of Greece : A Techno-economic and Environmental ApproachKastis, Stelios, Kitsios, Vaggelis January 2017 (has links)
The human effort to continuously improve their standard of living in conjunction with the rapid growth of world‟s population, the reckless and the wasteful misuse of energy reserves threaten to lead mankind in an energy deadlock. In an effort to realize the size of the waste of our planet‟s available energy resources, we only need to point out that people have spent the last century stocks of raw materials and energy, which were saved and produced during the lifetime of our planet. The management of the energy systems in a proper and best way is considered to be essential worldwide. In this project the energy system of Greece is studied. The power production systems used in different sectors of life were analyzed. The study emphasized in the electricity production from different sources. Lignite electricity power plants were first introduced in the country followed by the gas power plants and Renewable Energy Sources (RES) installations. The deregulation of electricity market formed the new energy scenery of the country. Electricity grid reinforcements with smart metering and energy storage proved to be necessary in order the RES to be fully penetrated to the national grid, so as Greenhouse Gas (GHG) emissions to be reduced as much as possible. The further expansion of RES could help to cope with the barriers of the country‟s electrification due to singularity of hundred islands that are not yet interconnected to the mainland. Analytical theory methods and numerical skills used to derive the appropriate data and results. Installed capacity of the power sources was verified as well as costs and polluted emissions per unit and type of sources involved. Weaknesses and abnormalities of the electric system were pointed out. Proved gains from the RES use were verified for ensuring the sustainability of the country‟s energy system
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Coping mechanisms of low-income urban households to escalating energy costs in South AfricaDlamini, Khetsiwe Thandeka Hazel January 2016 (has links)
A research report submitted to the Faculty of Engineering and the Built Environment at the University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Architecture (Sustainable Energy Efficient Cities) / Whereas the escalation of energy costs in South Africa over the past 5-years has been systematically reported, the extent to which low-income urban households are coping with the escalation has not been studied. Based on ethnographic data from Etwatwa in Ekurhuleni and secondary data from the Department of Energy and Statistics South Africa, the study evaluates the extent to which ongoing energy poverty mitigation programmes under FBE (Free Basic Electricity) and FBAE (Free Basic Alternative Energy) are facilitating how such households cope with the escalating costs. One of the key findings of the study is that FBE is not only inadequate for beneficiary household needs but also fails to accommodate large family sizes whose consumption goes beyond the set threshold of 450kWh/month. Since FBAE is only available for households not yet connected to the grid, the programme would not serve as a complementary intervention for households not benefiting from FBE due to consumption beyond the threshold.
Based on the key finding of inadequacy of existing mitigation interventions (declining affordability of electricity, unresponsiveness of FBE to large-family size and the barrier to accessing FBAE while connected to grid) the study finds that energy poverty among low-income households and communities is deepening. As coping strategies, households resort to switching to alternative combustible fuels like paraffin, wood, coal, and solid waste which leads to indoor and outdoor air-pollution with related respiratory illnesses and under severe situations they resort to suppressing demand through options such foregoing cooked meals, irregular bathing/cleaning and space-heating in winter.
The findings also allowed the study to critique the energy ladder model on its assumptions on linear energy carrier transitions in line with improved incomes of low-income households. In particular, the study finds that even as incomes of affected households improve, an ever increasing share of the income goes towards covering the escalating energy costs but still never managing to close the affordability gap for clean energy thus reinforcing a vicious cascade in energy poverty In order to systematically mitigate these escalating patterns of energy poverty,
the study recommends the distribution of renewable technology through a more innovative FBAE policy which would allow municipalities, national government and other stakeholders to commit to more equitable long-term investments in energy efficiency and renewable energy interventions for such households.
Key words: escalating energy costs, coping mechanism, energy poverty, Free Basic Electricity, Free Basic Alternative Energy
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Análise econômica financeira comparativa da autoprodução direta ou conectada no SIN - um estudo de caso. / The comparative economic financial analysis of the direct self production or connected to SIN (National Interconnected System) case analysis.Midea, Leonardo Granada 26 May 2009 (has links)
Este trabalho tem como objetivo principal verificar a viabilidade econômica financeira da autoprodução direta e interligada, isto é, elaborar uma comparação entre uma usina hidrelétrica ligada diretamente à unidade de consumo, e uma usina ligada ao Sistema Interligado Nacional, com potência e energia asseguradas. Para isso, foram utilizados, como premissas, uma indústria de alumínio que, como parte integrante dos grandes consumidores de energia brasileira, é um tipo de indústria eletro-intensiva, e emprega milhares de pessoas direta e indiretamente; também uma usina hidrelétrica, que neste trabalho foi a UHE Piraju, usina de concessão da CIA BRASILEIRA DE ALUMÍNIO, que gentilmente cedeu os dados de geração física real. Foram adotadas as seguintes metodologias para comparação da viabilidade, utilizando um cenário de geração e preços SPOT dos anos de 2006 e 2007: (i) Autoprodução Direta: Geração física real, comercializando excedentes e comprando energia do mercado ao preço SPOT quando necessário, e considerando todos os encargos e benefícios deste tipo de ligação; (ii) Autoprodução Conectada no SIN: Energia Assegurada Sazonalizada em 3 cenários distintos, Flat, com sazonalização moderada e sazonalização otimizada, considerando também os custos de conexão e encargos pertinentes para cada cenário. Os resultados apresentados mostram que, por pouca margem de diferença, foi mais vantajoso o cenário com a energia assegurada otimizada, porém, é possível verificar que, ponderando os resultados apresentados nos diversos cenários, verificamos que é mais viável a usina ligada diretamente à carga, pois a previsibilidade do mercado de preços de curto prazo é pequena, e dificilmente se acertaria com precisão os PLD´s registrados no ano seguinte ao da sazonalização. Contudo, o Decreto no 5.163, de 30 de Julho de 2004, através do Artigo 71, somente permite que usinas sejam ligadas diretamente à carga se estiverem dentro do mesmo sítio. O proposto é a inclusão de um novo parágrafo no Artigo 71 com condições de economicidade para a permissão da ligação da usina diretamente ao consumo. / The main goal of this study is to verify the economic financial feasibility of the direct self production, it means, of a hydropower unit directly connected to a consumption unit and to a hydropower unit connected to the SIN, with guaranteed power and energy. For this purpose, the study used as pattern an aluminum industry, which, as part of the Brazilian hall of the major energy users, a type of electric-intensive industry, and that involves thousands of employees directly and indirectly, as well as an hydroelectric power unit, which in this study was the UHE Piraju, the energy authorized supplier unit of the CIA BRASILEIRA DE ALUMÍNIO, who gently provided the real generation data. The following methodology were adopted to compare the feasibility, using a generation scenario and SPOT values of 2006 and 2007: (i) Direct Self Production: Real generation, trading leftovers and acquiring market energy at SPOT values, when required, and considering all costs and benefits of this type of connection; (ii) SIN Connected Self production: guaranteed seasoned energy in different scenarios, Flat, with seasonalization moderated and seasonalization optimized, also considering the connection and applicable costs for each scenario. The presented results indicated that, for a small difference, the most advantageous scenario was the one with optimized guaranteed energy, however, it is possible to verify that evaluating the presented results in the different cases, it was verified that is more feasible the unit directed connected to a demand, since the forecast of short term values market is small, and it would hardly precise ascertain with the registered PLD (Settlement Price for the Differences) in the following year of the seasonalization. However, the Act n. 5.163, July 30, 2004, through the Article 71 only allows power units to be connected to the demand if they are in the same site. The proposal is the inclusion of a new paragraph in the Article 71 with economic conditions in order to allow the connection between the power unit to the consumption.
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Análise econômica financeira comparativa da autoprodução direta ou conectada no SIN - um estudo de caso. / The comparative economic financial analysis of the direct self production or connected to SIN (National Interconnected System) case analysis.Leonardo Granada Midea 26 May 2009 (has links)
Este trabalho tem como objetivo principal verificar a viabilidade econômica financeira da autoprodução direta e interligada, isto é, elaborar uma comparação entre uma usina hidrelétrica ligada diretamente à unidade de consumo, e uma usina ligada ao Sistema Interligado Nacional, com potência e energia asseguradas. Para isso, foram utilizados, como premissas, uma indústria de alumínio que, como parte integrante dos grandes consumidores de energia brasileira, é um tipo de indústria eletro-intensiva, e emprega milhares de pessoas direta e indiretamente; também uma usina hidrelétrica, que neste trabalho foi a UHE Piraju, usina de concessão da CIA BRASILEIRA DE ALUMÍNIO, que gentilmente cedeu os dados de geração física real. Foram adotadas as seguintes metodologias para comparação da viabilidade, utilizando um cenário de geração e preços SPOT dos anos de 2006 e 2007: (i) Autoprodução Direta: Geração física real, comercializando excedentes e comprando energia do mercado ao preço SPOT quando necessário, e considerando todos os encargos e benefícios deste tipo de ligação; (ii) Autoprodução Conectada no SIN: Energia Assegurada Sazonalizada em 3 cenários distintos, Flat, com sazonalização moderada e sazonalização otimizada, considerando também os custos de conexão e encargos pertinentes para cada cenário. Os resultados apresentados mostram que, por pouca margem de diferença, foi mais vantajoso o cenário com a energia assegurada otimizada, porém, é possível verificar que, ponderando os resultados apresentados nos diversos cenários, verificamos que é mais viável a usina ligada diretamente à carga, pois a previsibilidade do mercado de preços de curto prazo é pequena, e dificilmente se acertaria com precisão os PLD´s registrados no ano seguinte ao da sazonalização. Contudo, o Decreto no 5.163, de 30 de Julho de 2004, através do Artigo 71, somente permite que usinas sejam ligadas diretamente à carga se estiverem dentro do mesmo sítio. O proposto é a inclusão de um novo parágrafo no Artigo 71 com condições de economicidade para a permissão da ligação da usina diretamente ao consumo. / The main goal of this study is to verify the economic financial feasibility of the direct self production, it means, of a hydropower unit directly connected to a consumption unit and to a hydropower unit connected to the SIN, with guaranteed power and energy. For this purpose, the study used as pattern an aluminum industry, which, as part of the Brazilian hall of the major energy users, a type of electric-intensive industry, and that involves thousands of employees directly and indirectly, as well as an hydroelectric power unit, which in this study was the UHE Piraju, the energy authorized supplier unit of the CIA BRASILEIRA DE ALUMÍNIO, who gently provided the real generation data. The following methodology were adopted to compare the feasibility, using a generation scenario and SPOT values of 2006 and 2007: (i) Direct Self Production: Real generation, trading leftovers and acquiring market energy at SPOT values, when required, and considering all costs and benefits of this type of connection; (ii) SIN Connected Self production: guaranteed seasoned energy in different scenarios, Flat, with seasonalization moderated and seasonalization optimized, also considering the connection and applicable costs for each scenario. The presented results indicated that, for a small difference, the most advantageous scenario was the one with optimized guaranteed energy, however, it is possible to verify that evaluating the presented results in the different cases, it was verified that is more feasible the unit directed connected to a demand, since the forecast of short term values market is small, and it would hardly precise ascertain with the registered PLD (Settlement Price for the Differences) in the following year of the seasonalization. However, the Act n. 5.163, July 30, 2004, through the Article 71 only allows power units to be connected to the demand if they are in the same site. The proposal is the inclusion of a new paragraph in the Article 71 with economic conditions in order to allow the connection between the power unit to the consumption.
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The Word Problem Factor: Assessing the Ability of Utah High School Career and Technical Education Students to Do the Math Involved in Formulating and Calculating Energy Cost FactorsBentley, Kristen 01 December 2014 (has links) (PDF)
Much research has been done showing the difficulty people have with word problems. This has been shown to be true for many types of word problems and for different demographics. Questions have remained unanswered regarding the reasons for this difficulty. It has been unclear if the word problems were hard because the people had forgotten or had not yet learned how to do the math calculations involved or for some other reason. This study deals with high school students who are currently in a high school level math class. They were given an assessment involving word problems and number-only problems. The results demonstrate that these students can do the math calculations needed for the problems but that the difficulty lies in their ability to formulate the word problems into correct mathematical expressions. Among the students in math classes higher than Secondary 2, it cannot be shown that those who have passed Financial Literacy demonstrate a significantly higher ability to do word problems with p > 0.05.
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Rekommenderad framledningstemperatur i fjärrvärmenät baserat på rökgaskondensering : En beräkningsundersökning av rökgaskondensering och fjärrvärme i en medelstor svensk stadHwit, Emil January 2019 (has links)
Fjärrvärme är den vanligaste uppvärmningsformen i Sverige och mer än hälften av alla lokaler och bostäder får sin uppvärmning från gemensamma fjärrvärmeanläggningar. Rökgaskondensering producerar 11 % av all fjärrvärme vilket gör den till den tredje största fjärrvärmeproducenten i Sverige. Det är därför är det viktig att den är så effektiv som möjligt. För att öka effektiviteten i förbränningsanläggningar i fjärrvärmesystem kan rökgaskondensering installeras i sammanband med de flesta bränslen som avger fuktig ånga. Rökgaskondenseringen har en viktig roll i samhället då den tar vara på energi som annars skulle gå förlorad samtidigt som den kan rena avgaserna från förorenade utsläpp. Borlänge‑Energi äger ett rökgaskondenseringssystem på Stora Enso Kvarnsvedens Pappersbruk. De vill nu utreda om deras rökgaskondenseringssystem körs så effektivt som den skulle kunna göra. Den här rapporten undersöker därför hur driften påverkas av förändrade fram- och returledningstemperaturer samt vad produktionskostnadsförändringarna på den producerade värme blir. Beräkningar har genomförts med hjälp av fjärrvärmevattnets densitet, specifikvärmekapacitet, flödes- och temperaturskillnad i Excel. Alla beräkningar har utgått från medianvärdet för månaden och sedan jämförts med vad som händer vid förändrad fram‑ och returledningstemperatur. Som underlag för beräkningarna har data insamlad under perioden januari 2015 och december 2018 använts. Resultatet visar att öka framledningstemperaturen till 95 °C från medianframledningstemperaturerna för respektive månad, det vill säga från temperaturintervall på 79 – 88 °C till 95 °C, ökar energikostnaderna med cirka 2,5 miljoner SEK per år. Kostnaden kan minskas med 400 000 SEK/år genom att sänka returledningstemperaturen till 40 °C. Minskas istället framledningstemperaturen till 75 °C när utomhustemperaturen är varmare än ‑1 °C, minskar de nuvarande energikostnaderna. En minskad framledningstemperatur ger även minskade förluster i ledningarna, minskat slitage, minskad bränsleförbrukning och minskade utsläpp. Temperatursänkning till 75 °C från temperaturintervallet 79 – 88 °C kan minska kostnaderna med 620 000 SEK per år. Skulle returledningstemperaturen sänkas men framledningstemperaturen bibehållas som den är idag kan en kostnadsminskning på över 400 000 SEK nås. Genom att sänka både fram- och returledningstemperaturerna kan en kostnadssparning på över 1 miljon SEK per år ske. Den framledningstemperatur som rekommenderas att Borlänge‑Energi strävar efter är: 75 °C när utomhustemperaturen är varmare än -1 °C 80 °C mellan -2 och -4 °C 85 °C vid -5 °C 90 °C mellan -6 och ‑7 °C 95 °C mellan -8 och -11 °C / The most common way of heating buildings in Sweden is by district heating, more than half of all the locales and homes is heated this way. Flue gas condensation is the third largest contributor of energy in district heating at 11 %. The importance of its efficiency is thereby big. Flue gas condensation can be installed at combustion boilers to increase the efficiency, it can be used in combination with most fuels that exhaust steam. The flue gas condensation has an important role by harnessing the energy in flue gases and cleansing it from environmental hazards. The flue gas condensation unit on Stora Enso Kvarnsveden Mill is owned by Borlänge‑Energi. They want to know if the condenser is operating as effective as it could be. This report investigates how the condenser and external heater at Stora Enso Kvarnsveden Mill is affected by different supply and return temperatures as well as what the production costs of the energy is. The calculations have been accomplished by using the density, specific heat capacity, flow- and temperature differences in Excel. All the calculations have originated from the median value for each month and used in comparison. The basis of the calculations is data that has been collected in the period of January 2015 to December 2018. The results indicate that increasing the supply temperature to 95 °C increases the energy costs by about 2 500 000 SEK per year. These costs can be reduced by 400 000 SEK per year by decreasing the return temperature to 40 °C. If the supply temperature is instead decreased to 75 °C when the temperature outside is higher than -1 °C, the costs decreases. A low supply temperature leads to less wear on the pipes, less heat losses, less fuel consumption and less emissions. This temperature reduction can decrease the costs by 620 000 SEK per year. If the return temperature is reduced but the supply temperature retained as it is today the costs could decrease by over 400 000 SEK per year. And by reducing both the supply and return temperature a cost saving of over 1 000 000 SEK per year could be achieved. The recommendation is therefore a lowering of the supply temperature to 75 °C when the temperature outside is warmer than -1 °C. The recommended supply temperature is: 75 °C when the temperature outside is warmer than -1 °C 80 °C between -2 and -4 °C 85 °C at -5 °C, 90 °C between -6 and ‑7 °C 95 °C between -8 and -11 °C
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Otimização energética em tempo real da operação de sistemas de abastecimento de água / Real-time optimization of water supply system operationCunha, Alice Araújo Rodrigues da 12 May 2009 (has links)
Este trabalho apresenta um modelo computacional para otimização energética de sistemas de abastecimento em tempo real. Tal modelo é composto por três módulos principais: (1) um módulo de simulação hidráulica que descreve o comportamento do sistema - EPANET; (2) um módulo de previsão de demandas que realiza a previsão das demandas futuras aplicável à utilização no tempo real (curto prazo), desenvolvido por Odan (2008); e, por fim, (3) um módulo otimizador estruturado em linguagem C++ que implementa a biblioteca de algoritmos genéticos do MIT - Massachusetts Institute of Technology and Matthew Wall, a GAlib, que permite determinar as rotinas operacionais (acionamento de válvulas e bombas) de forma à minimizar o custo de energia elétrica no sistema. O processo de otimização é divido em duas rotinas, nível estratégico e tempo real. Na otimização em nível estratégico, a partir das curvas típicas de demanda para cada nó de demanda do macro-sistema considerado, determina-se o conjunto de controles que minimizam os custos de energia elétrica, respeitando as restrições hidráulicas do sistema. Para cada conjunto de controles otimizados têm-se os níveis que os reservatórios irão atingir ao final de cada hora durante o horizonte de planejamento considerado, denominados níveis metas. Tais níveis servem de guia para a segunda etapa de otimização. A operação em tempo real se inicia com o recebimento dos dados sobre as condições atuais do sistema: níveis dos reservatórios e demandas da última hora. A partir das demandas informadas, o módulo de previsão de demandas gera todas as demandas para o horizonte de planejamento. Alimenta-se então o otimizador em tempo real com os níveis atuais dos reservatórios, os níveis metas e a previsão de demandas, obtêm-se o conjunto de regras operacionais ótimas para o horizonte de planejamento, sendo que são implementadas apenas as regras para a hora atual. E repete-se todo o processo a cada hora. Este modelo foi aplicado a um sistema de abastecimento de água. Os resultados obtidos demonstraram a eficiência do modelo em achar soluções factíveis de serem implementadas e com redução dos custos com energia elétrica. / This work presents a computational model for real-time optimization of water-distribution networks operation. An integrated software tool has been developed which is composed of three main modules: (i) a hydraulic simulator that performs the extended period simulation of the system (EPANET); (ii) a short-term demand-forecasting model, based on the moving Fourier series; and (iii) an optimization module, using genetic algorithm, to minimize pumping costs. The optimization process is divided in two routines, the off-line optimization and the on-line optimization. The aim of the first routine is to find the ideal operation levels for the reservoirs which are used as guidance for the on-line optimization. The schedules to be implemented in the network are determined, however, by an on-line optimization which runs a new optimization processes at each SCADA (Supervisory Control and Data Acquisition) update. In the off-line optimization, near-optimal pump and valve settings for a selected operating horizon are found on the basis of the typical 24-hour water demand cycle in which each reservoir must also start and end with the same water level. The levels of the reservoirs at the end of each hour in this optimization process, called ideal levels, are considered in the on-line optimization as a constraint that represents a penalty added to the objective function whenever a reservoir level is below the ideal level at the end of each hourly operation. The on-line optimization starts updating the state of the network transmitted from the SCADA system and the demand forecast for the next 24-hour period. Near-optimal pump and valve settings for a selected operating horizon are then determined but only the control settings for the next hourly time step are used to implement the operation. At the next SCADA update (next-time step), the whole process is repeated on a continuous basis and a new operating strategy is computed. In this way, the control process moves forward in time, correcting any discrepancies as it progresses. This integrated software tool has been applied to a small example network. The results obtained from this application have shown that the proposed model offers a practical tool for finding feasible operation strategies for a water pipeline system, obtaining reductions in pumping energy costs.
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Otimização energética em tempo real da operação de sistemas de abastecimento de água / Real-time optimization of water supply system operationAlice Araújo Rodrigues da Cunha 12 May 2009 (has links)
Este trabalho apresenta um modelo computacional para otimização energética de sistemas de abastecimento em tempo real. Tal modelo é composto por três módulos principais: (1) um módulo de simulação hidráulica que descreve o comportamento do sistema - EPANET; (2) um módulo de previsão de demandas que realiza a previsão das demandas futuras aplicável à utilização no tempo real (curto prazo), desenvolvido por Odan (2008); e, por fim, (3) um módulo otimizador estruturado em linguagem C++ que implementa a biblioteca de algoritmos genéticos do MIT - Massachusetts Institute of Technology and Matthew Wall, a GAlib, que permite determinar as rotinas operacionais (acionamento de válvulas e bombas) de forma à minimizar o custo de energia elétrica no sistema. O processo de otimização é divido em duas rotinas, nível estratégico e tempo real. Na otimização em nível estratégico, a partir das curvas típicas de demanda para cada nó de demanda do macro-sistema considerado, determina-se o conjunto de controles que minimizam os custos de energia elétrica, respeitando as restrições hidráulicas do sistema. Para cada conjunto de controles otimizados têm-se os níveis que os reservatórios irão atingir ao final de cada hora durante o horizonte de planejamento considerado, denominados níveis metas. Tais níveis servem de guia para a segunda etapa de otimização. A operação em tempo real se inicia com o recebimento dos dados sobre as condições atuais do sistema: níveis dos reservatórios e demandas da última hora. A partir das demandas informadas, o módulo de previsão de demandas gera todas as demandas para o horizonte de planejamento. Alimenta-se então o otimizador em tempo real com os níveis atuais dos reservatórios, os níveis metas e a previsão de demandas, obtêm-se o conjunto de regras operacionais ótimas para o horizonte de planejamento, sendo que são implementadas apenas as regras para a hora atual. E repete-se todo o processo a cada hora. Este modelo foi aplicado a um sistema de abastecimento de água. Os resultados obtidos demonstraram a eficiência do modelo em achar soluções factíveis de serem implementadas e com redução dos custos com energia elétrica. / This work presents a computational model for real-time optimization of water-distribution networks operation. An integrated software tool has been developed which is composed of three main modules: (i) a hydraulic simulator that performs the extended period simulation of the system (EPANET); (ii) a short-term demand-forecasting model, based on the moving Fourier series; and (iii) an optimization module, using genetic algorithm, to minimize pumping costs. The optimization process is divided in two routines, the off-line optimization and the on-line optimization. The aim of the first routine is to find the ideal operation levels for the reservoirs which are used as guidance for the on-line optimization. The schedules to be implemented in the network are determined, however, by an on-line optimization which runs a new optimization processes at each SCADA (Supervisory Control and Data Acquisition) update. In the off-line optimization, near-optimal pump and valve settings for a selected operating horizon are found on the basis of the typical 24-hour water demand cycle in which each reservoir must also start and end with the same water level. The levels of the reservoirs at the end of each hour in this optimization process, called ideal levels, are considered in the on-line optimization as a constraint that represents a penalty added to the objective function whenever a reservoir level is below the ideal level at the end of each hourly operation. The on-line optimization starts updating the state of the network transmitted from the SCADA system and the demand forecast for the next 24-hour period. Near-optimal pump and valve settings for a selected operating horizon are then determined but only the control settings for the next hourly time step are used to implement the operation. At the next SCADA update (next-time step), the whole process is repeated on a continuous basis and a new operating strategy is computed. In this way, the control process moves forward in time, correcting any discrepancies as it progresses. This integrated software tool has been applied to a small example network. The results obtained from this application have shown that the proposed model offers a practical tool for finding feasible operation strategies for a water pipeline system, obtaining reductions in pumping energy costs.
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