931 |
Metodologia para planejamento de ações de alívio de carregamento em sistemas de distribuição de energia elétrica em média tensão / Methodology for planning of load shedding actions in electrical power distribution systems in medium voltageGuilherme Pereira Borges 14 June 2016 (has links)
O objetivo desta tese é desenvolver e implementar em computador uma metodologia para resolver o problema de alívio de carregamento utilizando técnicas de remanejamento ou corte de carga. Tal metodologia, fundamenta-se no Algoritmo Evolutivo Multiobjetivo em Tabelas, que foi desenvolvido inicialmente para o problema de restabelecimento de energia em sistemas de distribuição. Já metodologia desenvolvida nesta tese trata o problema de alívio de carregamento, buscando minimizar o número de consumidores sem fornecimento de energia elétrica e o número de operações de chaveamento. Todavia, é necessário a obtenção de um plano de manobras em chaves adequado de modo que este não inviabilize a implantação na prática e que resulte em soluções que contemplem: a ausência de sobrecarga na rede e nas subestações, a manutenção dos níveis de tensão dentro dos intervalos exigidos pela legislação e a manutenção da radialidade da rede. Para alcançar estes objetivos, utiliza-se técnicas que determinam a sequência de chaveamento necessária para o plano de alívio de carga obtido. Prioriza-se, ainda, o atendimento aos consumidores prioritários e o corte seletivo de cargas em condições de esgotamento das possibilidades de remanejamento entre os alimentadores primários. Ao aplicar a metodologia proposta em um sistema de distribuição real de grande porte da Companhia Energética de Pernambuco - CELPE, constatou-se que, em comparação com a técnica atualmente utilizada, a metologia desenvolvida é confiável e apresenta bons resultados no que se refere a: sequência exequível de manobras, diminuição do número de chaveamentos e redução do número de consumidores e consumidores prioritários sem atendimento. Além disso, a metodologia possui capacidade de aplicação em outros sistemas semelhantes e foi integrada em um sistema computacional com ambiente gráfico permitindo estudos de caso e armazenamento em banco de dados. / The objective of this research is to develop and implement a methodology for the treatment of load shedding problem due to the existence (operation) or the possibility to occur (planning) contingencies in supply system (High Voltage/Subtransmission). The methodology is based on Multiobjective Evolutionary Algorithm in Tables, initially developed for the service restoration problems in distribution systems. It aims to minimize the number of customers without electricity supply; minimizing the number of switching operations, so that it does not impede the implementation in practice; absence of overload in network and substations; maintaining the voltage levels within the ranges required by the laws of radiality and maintenance of the network. To achieve these goals, are used techniques for determining the required switching sequence for the load shedding plan obtained; prioritization of special consumer in service and selective load shedding when exhausted the possibilities of relocating loads between primary feeders. When applies the proposed methodology in a real large distribution system of the Energy Company of Pernambuco - CELPE, it can be seen that, compared with the technique currently used, it is reliable with good results regarding viable sequence of maneuvers; reducing the number of switchings and number of consumers and priority consumers without service in addition to be able to be applied in similar systems. The methodology has been integrated into a computer system in a graphical environment with facilities of case studies and storing information in the database.
|
932 |
Consumo desagregado de energia: técnicas de monitoramento não intrusivo. / Disaggregated energy consumption: nonintrusive load monitoring techniques.Eduardo Kanashiro 19 November 2015 (has links)
As Ações de Eficiência Energética encontram grandes barreiras para sua implantação. Um dos motivos pode estar na falta de conhecimento do tomador de decisão que, para evitar o custo inicial mais elevado de um equipamento eficiente, opta por instalar um equipamento mais barato, mas que consequentemente consome mais energia e aumenta os dispêndios com a eletricidade. Os sistemas de gestão de energia visam demonstrar a origem das despesas relacionadas ao consumo de energia elétrica, conscientizando os usuários acerca de tais custos. Muitos usuários não enxergam a possibilidade de economia de energia e de dinheiro, ao investir em equipamentos mais eficientes. Muitos consideram as faturas de energia como despesas fixas, logo, sem exigência de acompanhamento. Fato não compatível com os dias atuais. Ao identificar o consumo desagregado de energia da instalação, os usuários poderão avaliar os impactos de suas atividades em relação ao consumo de energia, assim com seu custo nas faturas de energia. A medição direta dos equipamentos reproduz o valor mais preciso do consumo desagregado. Entretanto, para muitas instalações esta prática é inviável, pois seus circuitos são compartilhados por diversos tipos de equipamentos e os custos de aquisição, implantação e leitura dos medidores podem se tornar proibitivos. É possível obter o valor do consumo desagregado por inspeção da instalação, que consiste no levantamento das características elétricas dos equipamentos, suas respectivas potências e períodos de utilização. Esse método, no entanto não é tão preciso na análise do consumo desagregado, pois envolve uma série de estimativas acerca da utilização dos equipamentos, que nem sempre são acertadas. Visando contornar estas situações, as técnicas de monitoramento não intrusivo de carga passaram a buscar na curva de carga as assinaturas elétricas dos equipamentos, para identificar seus períodos de funcionamento e assim obter o consumo desagregado. / The energy efficiency programs face huge difficulties to be deployed. The reason may be the lack of knowledge about total costs in acquires less efficient devices, which is cheaper, though the increases in energy bills eliminate this initial economy. Thereby, the Energy Management Systems aims to demonstrate the relation between the user\"s behavior and the electric power consumption. Many managers consider the electric bill as a fixed cost, without require tracking its origin. This means waste of energy and money. Analyzing the facility by sectors may improve the understanding about the costs in electricity and the knowledge about the disaggregated energy consumption, though is not always an easy issue to be obtained. Monitoring each equipment provides the exactly amount of energy is used in that system. However the costs of acquirement, implementation and monitoring these meters may become prohibitively. This way, the researches about nonintrusive load monitoring aim to demonstrate where the energy is being used and how it can be minimized.
|
933 |
Proračuni tokova snaga neuravnoteženih distributivnih mreža / Load Flow calculations for unbalanced distribution networksVidović Predrag 12 February 2015 (has links)
<p>U disertaciji je predstavljen postupak GSSKN (generalizovani postupak sumiranja<br />struja i korekcija napona) integrisan u DMS. Integracija postupka GSSKN u DMS se<br />sastoji od sledećeg: 1) postupak GSSKN se naslanja na jedinstvenu bazu podataka DMS i<br />2) rezultati dobijeni proračunom tokova snaga korišćenjem postupka GSSKN koriste<br />se u velikom broju ostalih funkcija DMS. Standardni postupak BFS (čišćenje<br />unaprjed/unazad), koji je razvijen za proračun tokva snaga uravnoteženih<br />distributivnih mreža u simetričnim režimima, u ovoj disertaciji je generalizovan na<br />uravnotežene mreže u nesimetričnim režimima, neuravnotežene distributivne mreže<br />(u nesimetričnim režimima), sa obuhvaćenim miksovanim mrežama, a da su pri tome u<br />potpunosti zapaženi robustnost, efikasnost i brzina u odnosu na ostale postupke.<br />Odnosno, u ovoj disertaciji je predložen GSSKN za proračun bilo kako složenih<br />slaboupetljanih distributivnih mreža s distributivnim generatorima, koji ima sve<br />osobine i prednosti u odnosu na ostale postupke, kao što su ih imali standardni<br />postupci BFS za proračun tokova snaga uravnoteženih slaboupetljanih<br />distributivnih mreža sa distributivnim generatorima u simetričnim režimima.<br />Dakle, osnovni cilj ove disertacije glasi: pokazati da standardne postupke BFS ne<br />samo da ne treba napuštati prilikom proračuna tokova snaga neuravnoteženih<br />slaboupetljanih aktivnih mreža (uključene miksovane), već da je to napuštanje<br />kontraproduktivno, bar sa aspekta postupaka koji su do sada objavljeni u literaturi.</p> / <p>The dissertation presents GBFS (General Backward/Forward Sweeping) procedure<br />which is integrated in DMS. The integration of the GBFS procedure in DMS<br />consists of the following: 1) the GBFS procedure is based on the unique DMS<br />database and 2) the results obtained from load flow calculation by application of<br />GBFS procedure are used in many other DMS applications. The standard BFS<br />procedure (Backward/Forward Sweeping), developed for the load flow calculation<br />of balanced distribution networks in symmetrical states, in this dissertation is<br />generalized to balanced networks in asymmetrical states, unbalanced distribution<br />networks (in asymmetrical states), including mixed networks. In addition, the<br />robustness, efficiency and speed comparing to other procedures, have been saved.<br />In other words, this dissertation proposes the GBFS procedure for calculation of<br />any composite weakly meshed distribution networks with distribution generators. It<br />has all the properties and advantages as compared to other procedures, like<br />standard BFS procedures applied for load flow calculation of balanced weakly<br />meshed distribution networks with distribution generators in symmetrical states.<br />Therefore, the basic objective of this dissertation is as follows: to show that the<br />standard BFS procedures should not be abandoned when performing the load flow<br />calculation of unbalanced weakly meshed active networks (mixed included), and<br />that, on the contrary, abandoning them would be counterproductive, at least from<br />the aspect of procedures published so far.</p>
|
934 |
Influência do clima no desempenho energético de condicionador de ar com tecnologia VRF em condição de carga parcial para hotéisXavier, Ademilson dos Santos 13 October 2016 (has links)
Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2017-02-08T12:58:24Z
No. of bitstreams: 1
Ademilson dos Santos Xavier_.pdf: 9916385 bytes, checksum: 8bcbfe8f2b36b5a58781ce2518c1bb83 (MD5) / Made available in DSpace on 2017-02-08T12:58:24Z (GMT). No. of bitstreams: 1
Ademilson dos Santos Xavier_.pdf: 9916385 bytes, checksum: 8bcbfe8f2b36b5a58781ce2518c1bb83 (MD5)
Previous issue date: 2016-10-13 / Nenhuma / Estudos recentes mostraram que uma grande parte da energia elétrica consumida no Brasil destina-se a edificações do setor Comercial e Público. Observando-se que o sistema de HVAC (Heating, Ventilation, and Air Conditioning) apresenta relevante papel no quadro final do consumo energético em edificações, a determinação de seus requisitos mínimos de eficiência energética torna-se o fator chave para o sucesso de qualquer programa de certificação energética em construções. Esse trabalho tem como objetivo avaliar de que forma as condições climatológicas brasileiras podem influenciar o desempenho de um sistema condicionador de ar com tecnologia VRF (Variable Refrigerant Flow) em Condições de Carga Parcial (Part Load Conditions), para uma edificação comercial. Para isso, foi desenvolvida uma metodologia capaz de identificar as localidades que foram objetos desse estudo. As cidades selecionadas foram: São Paulo (SP), Rio de Janeiro (RJ), Fortaleza (CE) e Brasília (DF). Após esta etapa, a caracterização do edifício modelo de referência (hotel) foi concretizada. Características físicas, valores de carga térmica externa e interna, e o perfil de uso (taxa de ocupação) da edificação, foram tópicos abordados. O software de simulação utilizado foi o EnergyPlus e as suas respectivas curvas e equações de desempenho foram ajustadas com base nos dados de performance dos aparelhos condicionadores de ar que foram selecionados. O fabricante Toshiba foi escolhido. A performance dos equipamentos VRF foi analisada através de resultados como Carga Térmica global, Condição de Carga Plena, Condições de Carga Parcial, PLR (Part Load Ratio), COP (Coefficient of Performance) e ICOP (Coeficiente Integrado de Performance). Os resultados mostraram que apesar da Condição de Carga Plena (Full Load Condition) ser recomendada para dimensionar o sistema de HVAC, quando o objetivo principal for avaliar o desempenho energético desse sistema (HVAC) para um período mais longo de operação essa análise deve ser realizada através das Condições de Carga Parcial (Part Load Conditions). Para as quatro localidades estudadas os valores de desempenho obtidos através das simulações mostram que os equipamentos de ar condicionado VRF utilizados atingiram o seu coeficiente máximo de performance (COPmáx) na condição de 50% de PLR e um ICOP de 6,8, contra um COP de 3,4 na condição nominal e um ICOP de 3,7 de acordo com o Regulamento Técnico da Qualidade do Nível de Eficiência Energética de Edifícios Comerciais, de Serviço e Públicos, RTQ-C. / Currently studies have been shown that a large part of the electricity consumed in Brazil is intended to buildings Commercial and Public Sector. The HVAC system (Heating, Ventilation, and Air Conditioning) shows a significant role in the final frame of the energy consumption in buildings, determining its minimum requirements for energy efficiency becomes the key factor for the success of any program energy certification of buildings. This work aims to analyze how the Brazilian climatic conditions can influence the performance of air conditioner systems with VRF technology (Variable Refrigerant Flow) in the Part-Load Condition for a commercial building. Therefore a methodology was developed to identify the locations that were the subject of this study. The cities selected are: São Paulo (SP), Rio de Janeiro (RJ), Fortaleza (CE) and Brasília (DF). In addition the building characteristics have completed, external and internal thermal load values with their use profile have been analyzed. The software applied was EnergyPlus and their performance curves and equations have been adjusted according with the performance data of air conditioning units selected. The manufacturer Toshiba has been chosen. The VRF equipment performance was analyzed through results as Full-Load Condition, Part-Load Conditions, Part Load Ratio (PLR), COP and COP (Integrated Coefficient of Performance). The main results have showed that despite the Full-Load Condition is recommended to dimension the HVAC system, when the objective is the evaluation of the energy performance for a longer operation period this analysis should be carried out through Part-Load Conditions. For all of the four cities have studied the performance values obtained from the simulations show that the air-conditioning equipment VRF used reached their maximum performance coefficient (COPmáx) at 50% of PLR and ICOP 6.8, against a COP 3.4 in nominal condition and ICOP of 3.72 according to the Quality Technical Regulation of the Energy Efficiency Level Commercial Buildings, and Public Service, RTQ-C.
|
935 |
Proposed New Military Live Load for Highway Bridges in the United StatesParker, Walter P. 23 May 2019 (has links)
This thesis presents the results of a mathematical analysis of various live load combinations on highway bridge spans up to 304.8 meters (1,000 feet) total lengths. The analysis included continuous beams, but only the results for simple beams is presented. The analysis was performed using an independently developed Microsoft EXCEL spreadsheet computation, based on superposition and classical mechanics.
In this thesis, several actual bridge live loadings and several hypothetical live loadings were analyzed and compared to the American Association of State Highway and Transportation Officials Load and Resistance Factor Design method. Also considered was the new bridge design method adopted by the Louisiana Department of Transportation in March 2015. The evolution of bridge design loads is discussed, and the concept of the Military Load Classification is introduced and adapted to the bridge design analysis. The results of the analysis are presented, compared and interpreted for use in future bridge design.
|
936 |
Nya krav på livbåtskrokar : En studie om hur MSC.320(89) har påverkat säkerheten vid hantering av livbåtar / New requirements for lifeboat hooks : A study on how MSC.320(89) has influenced safety concerning the handling of lifeboatsNilsson, John, Berg, Daniel January 2019 (has links)
Sedan implementeringen av on-load release funktionen på samtliga livbåtskrokar har det skett många olyckor som följd av introduktionen med detta system. Detta problem diskuterades under Internationella Maritima Organisationens Maritime Safety Committee, 89:e sammanträde 2011. Under detta sammanträde utvecklades ändringar och tillägg till koden för International Life-Saving Appliances med syfte att bemöta detta problem. Fokus för denna studien är resolution MSC.320(89) vilket formulerades under det sistnämnda mötet. Resolutionen lade fram nya krav rörande on-load release livbåtskrokar. Syftet med denna studie är att förstå hur MSC.320(89) har påverkat säkerheten vid hantering av livbåtar. Studien har utförts genom en kvalitativ litteraturstudie med komplementerande intervju. Genom att jämföra orsakande faktorer vid livbåtsolyckor med det nya kraven så har man kunnat spekulera fram positiva effekter gällande säkerheten. Implementeringsprocessen består av godkännande för utformning och funktion, rigorösa tester iland, samt granskningskrav för samtliga ombordvarande system. Minskning i antalet rapporter om olyckor vilket sker till följd av on-load release krokar efter implementeringsprocessen av MSC.320(89) tyder på att det sker ett färre antal olyckor relaterade till on-load release system. Denna minskning kan möjligtvis påverkas av implementeringen med fallprevention devices vilket kan ha som effekt att maskera svikt av on-load release system. Det övergripande resultatet från studien tyder på att MSC.320(89) har haft en positiv inverkan vad gäller säkerheten vid hantering av livbåtar. / There have occured many accidents as a result of the mandatory implementation of on-load release mechanisms on all lifeboats. In order to combat the problem amendments to the International Convention for the Safety of Life at Sea and the International Life-Saving Appliances Code were put forth during the Maritime Safety Committee, 89th session, 2011. The focus of this study lies on a product of this meeting: resolution MSC.320(89). The resolution presents new requirements for the design and function of on-load release systems. The purpose of this study is to understand how MSC.320(89) has influenced safety concerning the handling of lifeboats. A qualitative literature study with a complementary interview was used to conduct this study. By comparing causal factors of accidents involving on-load release systems with the new requirements stated in MSC.320(89) speculations could be made pertaining to improved safety conditions. The implementation process for the new requirements included a design review and performance test of existing and new on-load release and recovery systems. Moreover all systems onboard merchant vessels were either inspected, modified or replaced in order to be made compliant with the amended Life-Saving Appliance code. A decline in the number of accident reports concerning on-load release systems following implementation was observed during the data collection phase of this study. This decline may imply a reduction in the number of accidents caused by on-load release systems however the use of fall-prevention devices may have stopped failing on-load release systems from ending in catastrophe. The overriding conclusion of this study infers that resolution MSC.320(89) has effected safety concerning the handling of lifeboats in a positive manner.
|
937 |
Performance of Polyurea Retrofitted Unreinforced Concrete Masonry Walls Under Blast LoadingCiornei, Laura 22 August 2012 (has links)
Unreinforced masonry walls subjected to blast loading are vulnerable to collapse and fragmentation. The objective of this thesis is to conduct experimental and analytical research for developing a blast retrofit methodology that utilizes polyurea. A total of four unreinforced masonry walls were constructed and tested under various shock tube induced blast pressures at the University of Ottawa Shock Tube Testing Facility. Two of the retrofitted walls had surface-sprayed polyurea. The results indicate that the use of polyurea effectively controlled fragmentation while significantly increased the load capacity and stiffness of masonry walls. Polyurea proved to be an excellent retrofit material for dissipating blast induced energy by providing ductility to the system and changing the failure mode from brittle to ductile. Single degree of freedom (SDOF) dynamic analyses were conducted as part of the analytical investigation. The results show that the analytical model provides reasonably accurate predictions of the specimen response.
|
938 |
Load balancing solution and evaluation of F5 content switch equipmentAhmed, Toqeer January 2006 (has links)
The Thesis focused on hardware based Load balancing solution of web traffic through a load balancer F5 content switch. In this project, the implemented scenario for distributing HTTPtraffic load is based on different CPU usages (processing speed) of multiple member servers.Two widely used load balancing algorithms Round Robin (RR) and Ratio model (weighted Round Robin) are implemented through F5 load balancer. For evaluating the performance of F5 content switch, some experimental tests has been taken on implemented scenarios using RR and Ratio model load balancing algorithms. The performance is examined in terms of throughput (bits/sec) and Response time of member servers in a load balancing pool. From these experiments we have observed that Ratio Model load balancing algorithm is most suitable in the environment of load balancing servers with different CPU usages as it allows assigning the weight according to CPU usage both in static and dynamic load balancing of servers.
|
939 |
WCDMA Cell Load Control in a High-speed Train Scenario : Development of Proactive Load Control Strategies / Belastningsreglering av WCDMA celler i ett tågscenario : Utvecklings av strategier för proaktiv belastningsregleringJoshi, Raoul, Sundström, Per January 2012 (has links)
Load control design is one of the major cornerstones of radio resource management in today's UMTS networks. A WCDMA cell's ability to utilize available spectrum efficiently, maintain system stability and deliver minimum quality of service (QoS) requirements to in-cell users builds on the algorithms employed to manage the load. Admission control (AC) and congestion control (CC) are the two foremost techniques used for regulating the load, and differing environments will place varying requirements on the AC and CC schemes to optimize the QoS for the entire radio network. This thesis studies a real-life situation where cells are put under strenuous conditions, investigates the degrading effects a high-speed train has on the cell's ability to maintain acceptable levels of QoS, and proposes methods for mitigating these effects. The scenario is studied with regard to voice traffic where the limiting radio resource is downlink power. CC schemes that take levels of fairness into account between on-board train users and outdoor users are proposed and evaluated through simulation. Methods to anticipatorily adapt radio resource management (RRM) in a cell to prepare for a train is proposed and evaluated through simulation. A method to detect a high-speed train in a cell, and the users on it, is outlined and motivated but not simulated. Simulation results are promising but not conclusive. The suggested CC schemes show a surprising tendency towards an increase in congestion avoidance performance. Proactive RRM shows a significant increase in QoS for on-board users. No negative effects to users in the macro environment is noticed, with regard to the studied metrics.
|
940 |
Customer Load Profiling and AggregationChang, Rung-Fang 28 June 2002 (has links)
Power industry restructuring has created many opportunities for customers to reduce their electricity bills. In order to facilitate the retail choice in a competitive power market, the knowledge of hourly load shape by customer class is necessary. Requiring a meter as a prerequisite for lower voltage customers to choose a power supplier is not considered practical at the present time. In order to be used by Energy Service Provider (ESP) to assign customers to specific load profiles with certainty factors, a technique which bases on load research and customers¡¦ monthly energy usage data for a preliminary screening of customer load profiles is required.
Distribution systems supply electricity to different mixtures of customers, due to lack of field measurements, load point data used in distribution network studies have various degrees of uncertainties. In order to take the expected uncertainties in the demand into account, many previous methods have used fuzzy load models in their studies. However, the issue of deriving these models has not been discussed. To address this issue, an approach for building these fuzzy load models is needed.
Load aggregation allows customers to purchase electricity at a lower price. In some contracts, load factor is considered as one critical aspect of aggregation. To facilitate a better load aggregation in distribution networks, feeder reconfiguration could be used to improve the load factor in a distribution subsystem.
To solve the aforementioned problems, two data mining techniques, namely, the fuzzy c-means (FCM) method and an Artificial Neural Network (ANN) based pattern recognition technique, are proposed for load profiling and customer class assignment. A variant to the previous load profiling technique, customer hourly load distributions obtained from load research can be converted to fuzzy membership functions based on a possibility¡Vprobability consistency principle. With the customer class fuzzy load profiles, customer monthly power consumption and feeder load measurements, hourly loads of each distribution transformer on the feeder can be estimated and used in distribution network analysis. After feeder models are established, feeder reconfiguration based on binary particle swarm optimization (BPSO) technique is used to improve feeder load factors. Test results based on several simple sample networks have shown that the proposed feeder reconfiguration method could improve customers¡¦ position for a good bargain in electricity service.
|
Page generated in 0.1442 seconds