• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 118
  • 109
  • 23
  • 16
  • 5
  • 5
  • 4
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 332
  • 332
  • 101
  • 100
  • 80
  • 79
  • 71
  • 51
  • 50
  • 48
  • 44
  • 43
  • 37
  • 36
  • 34
  • 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.
241

Redução de perdas tecnicas atraves de reconfigurações de redes de distribuição de energia eletrica sob demandas variaveis / Technical loss reduction by reconfiguration of electric distribution networks with variable demands

Bueno, Edilson Aparecido 18 March 2005 (has links)
Orientadores: Christiano Lyra Filho, Celso Cavellucci / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-07T20:13:55Z (GMT). No. of bitstreams: 1 Bueno_EdilsonAparecido_M.pdf: 1593593 bytes, checksum: ff2749c689002cc1c4de48ee0899defc (MD5) Previous issue date: 2005 / Resumo: Este trabalho apresenta uma nova visão para o problema de redução das perdas técnicas em sistemas de distribuição de energia elétrica, através de reconfiguração de redes. A principal inovação consiste em abordar o problema com a consideração explícita das variações de demandas, mas impondo-se a restrição de que as configurações devem permanecer fixas ao longo do período de planejamento. Esta característica abre a perspectiva de que a metodologia venha a ser usada na operação diária dos sistemas de distribuição. No entanto, leva a um problema de otimização bem mais complexo do que o caracterizado pela visão tradicional. Formulações para demandas fixas e variáveis são desenvolvidas. Duas metodologias distintas para abordagem do novo problema são elaboradas. A primeira utiliza a metodologia denominada Busca Menor Energia, inspirada na técnica de Abertura Seqüencial de Chaves. A segunda técnica, denominada Árvore de Aproximação, faz uso das idéias de árvore geradora de custo mínimo. Ambas são combinadas com uma busca local, denominada Troca de Ramos Generalizada, baseada na técnica de Troca de Ramos. Explora-se também uma extensão da metodologia Árvore de Aproximação caracterizada por associação com conceitos do método GRASP (Greedy Randomized Adaptive Search Procedure). Estudos de casos ilustram a aplicação das metodologias em redes de cidades brasileiras / Abstract: This work presents a new point of view for the technical losses reduction problem in electric power distribution systems, through network reconfigurations. The main innovation is the explicit consideration of demand variations and the use of a fixed configuration during the planning period. This last characteristic makes the methodology able to be used in the daily operation of distribution systems. However, it leads to an optimization problem more complex than approaches without demand variations. Formulations for fixed and variable demands are created. Two distinct methodologies for the resolution of the new problem are elaborated. The first one uses the Minimum Energy Losses methodology, inspired by the ¿Sequential Switch Opening¿ technique. The last one, called Approximation Tree, is based on algorithms for the minimum spanning tree problem. Both of them are combined with a local search procedure, called Branch Exchange by Energy, based on the ¿Branch Exchange¿ technique. An extension of the Approximation Tree methodology is proposed by using concepts of the well-known GRASP method (Greedy Randomized Adaptive Search Procedure). Case Studies demonstrate the application of the methodologies in Brazilian cities¿ networks / Mestrado / Automação / Doutor em Engenharia Elétrica
242

Conceitos e aplicações de um sistema gerencial de apoio a decisão aplicados a sistemas de distribuição de energia elétrica via internet. / Executive information system: concepts and application for utilities.

Adriano Galindo Leal 13 July 1999 (has links)
Nesta dissertação, são discutidas as vantagens e dificuldades de um Sistema Gerencial de Apoio a Decisão em um ambiente Intranet/Internet, sua execução, bem como a utilização de aplicações de bancos de dados na web. Um sistema dessa natureza, denominado SAG (Sistema de Apoio Gerencial), foi concebido para dar suporte às atividades de gerência, supervisão e controle da rede de distribuição de energia elétrica da Eletropaulo Metropolitana (São Paulo, Brasil). O SAG possibilita o estabelecimento de uma sistemática de supervisão, visando, a partir da análise das condições atuais da rede de distribuição e em função dos recursos disponíveis, permitir o acompanhamento da evolução da qualidade do fornecimento de energia elétrica. Disponibilizando informações que irão orientar ações para corrigir os possíveis desvios inadequados e fixar políticas e diretrizes a serem seguidas nos níveis gerenciais. Como resultado, é esperado tornar mais ágil o processo decisório, bem como o acesso a dados técnicos e de carregamento dos equipamentos da rede de distribuição. / In this dissertation are discussed the advantages and difficulties of an Executive Information System (EIS) implementation on an Intranet or Internet environment, as well as the use of Database applications on the web. An Executive Information System named SAG was implemented at Eletropaulo Metropolitana (São Paulo, Brazil); it was conceived to address maintenance, operational and engineering departments\' needs. The System allows the establishment of a systematic supervision to attend the quality of the electric energy supplied. The analysis of the actual distribution network conditions, the available resources and the electric energy supplied quality will guide the actions to correct possible inadequacies as well as set and fix policies and guidelines to be followed on a manager\'s level. As a result it\'s expected faster decision-making process and access on distribution network equipment\'s technical data and load.
243

Compactação e elevação da vida útil de transformadores de distribuição empregando óleo vegetal isolante. / Reduction and extension life of distribution transformers using insulating vegetable oil.

Vagner Vasconcellos 14 April 2016 (has links)
A busca no aumento da vida útil dos transformadores de distribuição, redução dos custos de manutenção e mitigação de falhas, leva ao desenvolvimento de novos materiais e critérios de exploração diferenciados desses ativos. Esta pesquisa apresenta o desenvolvimento de um novo transformador de distribuição compacto e mais eficiente utilizando óleo vegetal isolante totalmente biodegradável. Além de biodegradável, o óleo vegetal utilizado possui menor agressividade ambiental e maior capacidade térmica aumentando, a capacidade de carregamento do transformador sem comprometer a sua vida útil. A fim de atestar essa menor agressividade em relação ao óleo mineral, ensaios foram efetuados em um equipamento que permaneceu 12 anos em operação. O equipamento foi totalmente desmontado para análise e coleta de amostras de papel e óleo vegetal isolante. As análises visam comprovar a menor agressividade em relação ao óleo mineral, apresentadas na revisão bibliográfica. A menor agressividade torna possível a proposição de uma nova filosofia de planejamento de redes de distribuição utilizando uma quantidade menor dos novos transformadores para uma mesma carga, tornando-a mais compacta e eficiente. / The search of increase on the life expectancy of distribution transformers, reducing maintenance costs and mitigation failures, leads to the development of new materials and different operating criteria of these assets. This research presents the development of a new distribution transformer compact and more efficient with insulating in vegetable oil totally biodegradable. In addition to biodegradable, the vegetable oil used has less environmental aggressiveness and greater thermal capacity, increasing the loading capacity of the transformer without compromising its life expectancy. To prove that the vegetable oil is less aggressive than mineral oil, tests were done out in a transformer that worked for 12 years. The equipment was disassembled for analysis and collection of samples of vegetable oil and paper insulation. The analyses aim to prove the lesser aggressiveness compared to mineral oil, presented in the literature review. This situation makes it possible the proposition of a new philosophy of planning of distribution networks using a smaller amount of new transformers for the same load, making it more compact and efficient.
244

Smart Resistor: Control and Stabilization of DC Distribution Networks Utilizing Energy Storage with High Bandwidth Power Converters

Potty, Karun Arjun January 2020 (has links)
No description available.
245

Studie propojení skupinových vodovodů Lanškroun a Letohrad / Study of Interconnection of Lanškroun and Letohrad Water Distribution Systems

Kubešová, Kateřina January 2020 (has links)
This diploma thesis describes study of interconnection of Letohrad and Lanškroun water distribution systems. The thesis contains an overview of legislative regulations and technical standards related to the construction, design and directional solution of water supply systems. Following that, there is the description of the current state of the affected water mains. Next part is the design of interconnection including hydraulic analysis in using Epanet 2.0 software. The study contains several variants of the solution. The economic assessment is included.
246

Potenciál nefrekvenčních podpůrných služeb pro provozovatele distribuční sítě / Potential of non-frequency ancillary services for a distribution system operator

Reiskup, Filip January 2020 (has links)
This thesis provides a basic overview of the ancillary services in a transmission system. It summarizes changes regarding the implementation of European directives SOGL and EBGL. It describes in detail a portfolio of non-frequency ancillary services used in the distribution systems. It evaluates the demand of E.ON distribution system potential for those services in particular locations. Practical part is focused on a potential of reactive power management in this distribution area. It evaluates reactive power flow into transmission system and indicates the most critical substations. This thesis also covers analysis of existing resources in this distribution area and assign their possible potential in reactive power management.
247

Stochastické modelování spotřeby vody ve vodovodní síti / Stochastic modeling of water consumption in the water supply network

Kopecký, Josef January 2021 (has links)
This thesis deals with stochastic water demand modellling in the water supply network. In the opening section, a research is created, where two different approaches to stochastic modelling of water consumption are presented. The practical part describes the creation of a deterministic hydraulic model and its calibration. Generated stochastic water demand patterns with a small time step of 1 minute, are then inserted into this model. Each household is assigned with a unique water demand pattern. Then a hydraulic analysis was done. A comparison of deterministic and stochastic approaches is presented at the end of the thesis. The comparison shows, that small-time step modelling does not have a big impact on the pressure ratios in the water supply network, but has a huge impact on the maximum flows and speeds occurring in links of the hydraulic model.
248

Komplexní analýza funkce distribučního systému typu U / Complex analysis of the performance of a U-type distribution system

Sýs, Tomáš January 2021 (has links)
Fluid flow maldistribution plays a key role in equipment used in process and energy industries, although its evaluation is often underestimated or fully neglected. Uneven flow distribution may cause thermal or mechanical load on the tube bundle, and in extreme scenarios, it can also have an adverse effect on the process efficiency. This thesis aims to find the optimal computational tools for flow distribution prediction suitable for the initial stage of the equipment design process and to identify suitable settings of these tools for their subsequent industrial deployment. The results of simplified analytical models, detailed numerical simulations, and experimental measurements were compared for the dividing header and the U-type distribution system. It was found that the results provided by simplified mathematical models, the solution of which is also significantly less time-consuming compared to detailed CFD simulations, best correspond to the measured experimental values in all modeled configurations. For arrangements with higher lateral resistance coefficient, both computational approaches provide approximately equally accurate results. However, for arrangements with lower lateral resistance coefficient, the deviation of the results obtained by CFD calculations from the experimental data is significantly larger.
249

Rozptýlená výroba a jej vplyv na kvalitu dodávok elektrickej energie / Distributed Generation and its Influence on Power Quality

Bernáth, František January 2014 (has links)
This work deals with the deployment of distributed power sources into the electric power grid. The nature of these sources causes that the massive integration may experience problems with power quality in the local context, and also overall reliability of supply in the range of interconnected power systems may be endangered. Work is focused on local voltage quality problems with special emphasis on analysis and design of tools (e.g. reactive power compensation units of power plants or dynamic voltage control by transformers 110/22kV) for voltage control in power distribution systems. These tools should be used as a part of uniform concept of voltage control. The proposed concept is involved.
250

Hodnocení minimálních noční průtoků ve vodárenských systémech / Assessment of minimal night-flows in the water supply systems

Zvejška, Tomáš January 2016 (has links)
This Diploma thesis deals with minimum night flows issue. Basic findings about minimum night flows were summarized in the introductory part of thesis. Findings like the minimum night flow components, affecting parameters and used methodologies for assessment of minimal night flows. In the practical part of this thesis was this knowledge applied to real water distribution system in the municipality Hrádek u Sušice. The part of this thesis was also determinate the measurement accuracy of used water meter, which was formerly installed at the outlet in the Hrádek water tank. Measurement errors was determinate for the flow values, that are close to the real measured minimum night flow data in the water distribution system in municipality Hrádek u Sušice.

Page generated in 0.0327 seconds