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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Potential benefits of load flexibility: A focus on the future Belgian distribution system

Mattlet, Benoit 25 May 2018 (has links) (PDF)
Since the last United Nations Climate Change Conference in 2015 in Paris (the COP 21), world leaders acknowledged climate change. There is no need any more to justify the switch from fossil fuel-based to renewable energy sources. Nevertheless, this transition is far from being straightforward. Besides technologies that are not yet mature -- or at least not always financially viable in today's economy -- the power grid is currently not ready for a rapid and massive integration of renewable energy sources. A main challenge for the power grid is the inadequacy between electric production and consumption that will rise along with the integration of such sources. Indeed, due to their dependence on weather, renewable energy sources are intermittent and difficult to forecast with today's tools. As a commodity, electricity is a quite distinct good for which there must be perfect adequacy of production and consumption at all time and characterized by a very inelastic demand. High shares of renewable energy sources lead to high price volatility and a higher risk to jeopardize the security of supply. Additionally, the switch to renewable energy sources will lead to an electrification of loads and transportation, and thus the emergence of new higher-consumption loads such as electric vehicles and heat pumps. These new and higher-consumption loads, combined with the population growth, will cause over-rated power load increases with less predictable load patterns in the future.This work focuses on issues specific to the distribution power grid in the context of the current energy transition. Traditional low-voltage grids are perhaps the most passive circuits in power grids. Indeed, they are designed primarily using a fit and forget approach where power flows go from the distribution transformer to the consumers and no element has to be operated or regularly managed. In fact, low-voltage networks completely lack observability due to very low monitoring. The distribution grid will especially undergo drastic changes from this energy transition. Distributed sources and new high-consumption -- and uncoordinated -- loads result in new power flow patterns, as well as exacerbated evening peaks for which it is not designed. The consequences are power overloads and voltage imbalances that deteriorate grid components, such as a main asset like the medium-to-low voltage transformer. Additionally, the distribution grid is characterized by end-users that pay a price for electricity that does not reflect the grid situation -- that is, mostly constant over a year -- and allow little to no actions on their consumption.These issues have motivated authorities to propose a global approach to ensure security of electricity supply at short and medium-term. The latter requires, among others, the development of demand response programs that encourage users to take advantage of load flexibility. First, we propose adequate electricity pricing structures that will allow users to unlock the potential of such demand response programs; namely, dynamic pricings combined with a prosumer structure. Second, we propose a fast and robust two-level optimization, formulated as a mixed-integer linear program, that coordinates flexible loads. We focus on two types of loads; electric vehicles and heat pumps, in an environment with solar PV panels. The lower level aims at minimizing individual electricity bills while, at the second level, we optimize the power load curve, either to maximize self-consumption, or to smoothen the total power load of the transformer. We propose a parametric study on the trade-off between only minimizing the individual bills versus only optimizing power load curves, which have proven to be antagonist objectives. Additionally, we assess the impact of the rising share of flexible loads and renewable energy sources for scenarios from today until 2050. A macro-analysis of the results allows us to assess the benefits of load flexibility for every actor of the distribution grid, and depending on the choice of a pricing structure. Our optimization has proved to prevent evening peaks, which increases the lifetime of the distribution transformer by up to 200%, while individual earnings up to 25% can be made using adequate pricings. Consequently, the optimization significantly increases the power demand elasticity and increases the overall welfare by 10%, allowing the high shares of renewable energy sources that are foreseen. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished
12

Essays on nursery labor, sales contracts, and price discovery

Li, Cheng 18 March 2013 (has links)
Oregon's nursery and greenhouse industry has ranked the first in the State's agricultural for 18 years. The majority of nursery sales from the Pacific Northwest come from Oregon. Due to data limitations, empirical study of the Oregon nursery industry is rare. The present dissertation consists of three essays that analyze the demand and supply of inputs and outputs and the relationship between producers and retailers in the Oregon nursery industry. Chapter 2 identifies the major factors affecting farm labor supply and demand and evaluates their relative importance in the Oregon nursery industry from 1991 to 2008. Empirical results show that border control effort doesn't have an influential role in labor supply, while the Oregon and Mexican minimum wage do. It is because of the substantial gap between the U.S. and Mexican economies, reflected for an example in the minimum wage gap, which attracts a continual flow of immigrants. Risk of border apprehension is not great enough to prevent the flow. Increases in Oregon minimum wage is more effective than border apprehension policies in boosting the average wage and in reducing the number of hours that illegal immigrants work in the nursery sector. Chapter 3 investigates producers' and retailers' choices of, and reactions to, various contract types in the Oregon nursery industry from 2005 to 2010. As new and fast-growing retailers in the industry, big-box stores are less likely than independent retailers to make pre-order contracts with the producer. However, once a pre-order contract is chosen, big-box stores demand more days of pre-order interval than independent retailers do. Transactions with independent retailers exhibit – on average over the sample range – scale economies and scope diseconomies. Boosting per-transaction revenue scale and the number of species sold to big-box stores enhances transaction efficiency. Chapter 4 examines the interaction between supply and demand in Oregon nursery products. The result indicates that the production and transaction costs are major drivers on the supply side, while transportation costs and consumer demand for nursery products play important roles on the demand side. At the genus level, the supply elasticities of coniferous plants are larger than those of deciduous plants, which in turn are higher than those of flowering plants. The demand elasticities are the lowest in coniferous trees followed by deciduous plants, then flowering plants. Price discounts on plants with high demand elasticities would significantly boost sales and enlarge the market, while those on plants with low demand elasticities would have less sales impact. Empirically, patenting seems to bring no direct signs of greater profitability. The wholesale nursery may wish to reconsider the pricing and marketing policies of its patented plants to differentiate them more effectively from its non-patented plants. / Graduation date: 2013
13

[en] COMPETITION IN ELECTRIC ENERGY SYSTEMS - COMMERCIALIZATION AND STRATEGIES TO THE MARKETS / [pt] COMPETIÇÃO EM SISTEMAS DE ENERGIA ELÉTRICA COMERCIALIZAÇÃO E ESTRATÉGIAS PARA O MERCADO

JOAO CARLOS DE OLIVEIRA AIRES 05 December 2001 (has links)
[pt] No mundo inteiro o Setor Elétrico têm passado por mudanças radicais. A principal meta desse processo de restruturação foi promover a competição nos segmentos de geração, distribuição e comercialização energia elétrica e a participação de agentes privados no processo de produção. Essa reestruturação está baseada em uma otimização centralizada e nas seguintes premissas: Geradores ofertam sua produção em um Mercado Atacadista de Energia - MAE . Os agentes privados são livres para decidir sobre a construção de novas usinas e para competir por contratos de energia vendas com empresas distribuidoras e clientes individuais.O novo ambiente competitivo permite, no entanto, que em cenários de preços spots elevados as empresas Distribuidoras de energia elétrica possam vender as diferenças entre os valores de demanda contratados e consumidos. A possibilidade de retração de carga por meio de negociações com clientes pode resultar em sobras de energia que poderão ser vendidas diretamente no Mercado Spot. Por outro lado, a reação dos Geradores através de instrumentos financeiros adequados (como contratos bilaterais, contratos futuros e de opção) ou de políticas operacionais (via Operador do Sistema) podem resultar em um -jogo- de estratégias no MAE. Esta tese investiga alguns conceitos, metodologias e ferramentas computacionais desenvolvidas para a operação e comercialização da energia elétrica envolvendo análise de riscos e instrumentos financeiros. O problema de gerenciamento e retração forçada da demanda (elasticidade forçada) é decomposto em dois subproblemas:Subproblema de operação: usando programação dinâmica dual estocástica . Subproblema de análise de riscos: usando a teoria da utilidade O modelo proposto é avaliado através de um estudo de caso considerando os dados do sistema interligado Sul-Sudeste, para o qual são simuladas ações de retração da demanda. / [en] Electricity utilities all over the world have been undergoing radical changes in their market and its regulatory structure. A basic trend in this restructuring process has been to promote competition in generation, distribution/retailing segments and participation of private agents in the energy production process. This restructuring is based on centralized optimization, by market-oriented approaches: Generators bid prices for their energy in a Wholesale Energy Market - WEM. Instead of following an expansion schedule produced by a central planning agency, private agents are free to decide about the construction of generator units and to compete for energy sales contracts with utilities and individual customers.The competitive environment permits, however, which in high spot prices scenarios the electric utilities sell some differences between bilateral contract and real consumption. The possibility of load retraction by means of negotiations with clients would result in surplus generation which could be sold directly to the spot market. On the other hand, the reaction of the Generators via financial means (such as bilateral contracts, forward contracts and option prices) or operational policies from System Operator can result in a WEM -gaming-. This thesis investigates some conceptual issues, methodologies and computational tools developed to operation and commercialization of the electrical energy considering risk analysis and financial instruments. The demand side and retraction management problem is decomposed in two sub-problems: Operation sub-problem: uses stochastic dual dynamic programming (SDDP)tools Risk analysis sub-problem: uses utility theoryThe approach will be illustrated with a case study with data taken from the Brazilian system, where the demand side management is simulated and the numerical results are presented.
14

Measuring the Transition toward Less Energy Intensive Economies : modeling Solutions for the Demand-Side / Mesurer la transition vers des économies moins intensives en énergie : enjeux méthodologiques et modélisation de la demande

Atallah, Tarek 26 October 2016 (has links)
Le monde est actuellement confronté à une transition du marché de l'énergie qui est influencée notamment par la dynamique de la croissance économique globale, les négociations relatives aux changements climatiques et des prix de plus en plus volatils. Cette évolution rapide des réglementations et de la macro-économie transformera les conditions de la demande d'énergie, obligeant les gouvernements à acquérir un ensemble croissant d'outils quantitatifs pour mieux évaluer les résultats de leurs politiques fiscales. Cette thèse aborde cette problématique en analysant, par une approche basée sur les élasticités, les différentes facettes de la demande d'énergie dans le but d'achever une consommation énergétique durable. Cette approche est complémentée par l'analyse par grappes, la décomposition structurelle ainsi que par diverses outils économétriques appliques conjointement à l'échelle mondiale et nationale. Une attention particulière est faite sur la modélisation de la demande des marchés subsidiés notamment des pays du Conseil de Coopération du Golfe Arabique / The world is currently witnessing a transition in the energy scene that is significantly characterized by global economic growth dynamics, climate change negotiations and volatile energy prices. Rapidly evolving regulatory and macro-economic environments heavily impact on the demand-side of energy, forcing governments to acquire an ever-increasing set of quantitative tools to better assess the results of their taxation policies.This thesis addresses some of these issues by analyzing various facets of energy demand in order to generate sensible demand and price elasticities with real-life applications in sustainable energy management. For that purpose, a combination of cluster, decomposition and multiple econometric analysis is undertaken at global, regional and country-specific levels for households complemented by a policy analysis. A special focus is made on modeling consumer demand behavior for resource-rich economies of the Gulf Cooperation Countries, and the potential impact of removing residential electricity subsidies on the net societal welfare of Saudi Arabia.

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