Diseño de un aerogenerador de muy baja potencia para la alimentación de sistemas eléctricos aislados

[ES]En este Proyecto se desarrolla el diseño y la optimización de un aerogenerador de muy pequeña potencia enfocado a alimentar sistemas eléctricos aislados; concretamente, un sistema de iluminación. Se analizan todos los componentes del sistema aerogenerador, comparando las diversas alternativas posibles y eligiendo soluciones sencillas, baratas y eficientes para cada uno de ellos. Asimismo, se lleva a cabo un primer dimensionamiento de los mismos. El esfuerzo de diseño se ha centrado en las palas, por considerarse el componente más crítico y menos normalizado. Se han estudiado herramientas para su análisis detallado y su optimización desde el punto de vista aerodinámico, y éstas han sido implementadas en Matlab. Esto ha permitido generar un diseño óptimo ajustado a las necesidades del sistema. Asimismo, se han realizado las correspondientes tareas de planificación, analizado los múltiples beneficios de tipo técnico, económico, social y ambiental que la ejecución del presente Proyecto reportará, haciendo una programación completa del mismo y un análisis de los costes que supondrá.

Compensación del factor de potencia en instalaciones eléctricas industriales de baja tensión.

[ES]En las últimas décadas, la optimización de las instalaciones eléctricas se ha convertido en una de las prioridades más importantes de las empresas. En este sentido, la corrección del factor de potencia supone un importante tema a analizar y resolver. Hoy en día, se dispone de muchos métodos de compensación, pero en la mayoría de los casos, la implementación de baterías de condensadores resulta la mejor opción. Por otra parte, dependiendo de la distribución elegida en la instalación de los condensadores, se consiguen ciertas ventajas y desventajas en cuanto a componentes reactivas en el sistema eléctrico y costes finales de la compensación se refiere. Además del desarrollo teórico, se dispondrá de simulaciones realizadas en herramientas de cálculo que ayudarán a la comprobación de estas ideas.

Gestión Energética. Estimación de necesidades de potencia eólica.

[ES]Este trabajo de fin de grado (TFG) pretende analizar la evolución de la demanda en el sistema eléctrico peninsular y la potencia disponible para decidir si, en el medio plazo, será necesario incorporar nueva potencia o prescindir de alguna de las centrales existentes. El estudio considerará tanto fuentes de energía renovables como no renovables, centrándose en la necesidad, o no, de incorporar nueva potencia eólica. El TFG considerará los siguientes aspectos: el contexto energético de la península española, el análisis de la situación actual y previsiones. Este TFG responde a la necesidad de realizar una buena gestión energética con el objetivo reducir las emisiones de CO2 mejorando el uso de la energía eólica y optimizando el mix energético.

A novel measurement of dynamic friction

A tribometer, based on a pin-on-disc machine, uses a PZT drive to produce small sinusoidal fluctuations of sliding speed. The frequency and amplitude of these fluctuations can be controlled, and the dynamic response measured. Preliminary test results show that the dynamic friction variation is influenced by the contact materials, normal force, oscillation frequency and steady sliding speed. The variation of friction force amplitude and phase with frequency gives clues about the underlying state variables determining the friction. Modelling studies illustrate the expected behaviour for idealized friction laws governed by, for example, sliding speed, contact temperature, and "rate-state" laws. © 2008 SAE International.

Thermo-optical characterization of fluorescent rhodamine B based temperature-sensitive nanosensors using a CMOS MEMS micro-hotplate

A custom designed microelectromechanical systems (MEMS) micro-hotplate, capable of operating at high temperatures (up to 700 C), was used to thermo-optically characterize fluorescent temperature-sensitive nanosensors. The nanosensors, 550 nm in diameter, are composed of temperature-sensitive rhodamine B (RhB) fluorophore which was conjugated to an inert silica sol-gel matrix. Temperature-sensitive nanosensors were dispersed and dried across the surface of the MEMS micro-hotplate, which was mounted in the slide holder of a fluorescence confocal microscope. Through electrical control of the MEMS micro-hotplate, temperature induced changes in fluorescence intensity of the nanosensors was measured over a wide temperature range. The fluorescence response of all nanosensors dispersed across the surface of the MEMS device was found to decrease in an exponential manner by 94%, when the temperature was increased from 25 C to 145 C. The fluorescence response of all dispersed nanosensors across the whole surface of the MEMS device and individual nanosensors, using line profile analysis, were not statistically different (p < 0.05). The MEMS device used for this study could prove to be a reliable, low cost, low power and high temperature micro-hotplate for the thermo-optical characterisation of sub-micron sized particles. The temperature-sensitive nanosensors could find potential application in the measurement of temperature in biological and micro-electrical systems. The Authors. © 2013 Published by Elsevier B.V. All rights reserved.

Ambiguities and Deviations in Qualitative Circuit Analysis

Lee M.H., Bell J. and Coghill G.M., Ambiguities and Deviations in Qualitative Circuit Analysis, in Proc. QR?2001, 15th Int. Workshop on Qualitative Reasoning, San Antonio, Texas, May 2001, pp51-58.

An Autonomous Sailing Robot for Ocean Observation

Sauze, C. and Neal, M. 'An Autonomous Sailing Robot for Ocean Observation', in proceedings of TAROS 2006, Guildford, UK, Sept 4-6th 2006, pages 190-197.

Fast Response Exhaust Gas Temperature Measurement in IC Engines

The harsh environment presented by engines, particularly in the exhaust systems, often necessitates the use of robust and therefore low bandwidth temperature sensors. Consequently, high frequencies are attenuated in the output. One technique for addressing this problem involves measuring the gas temperature using two sensors with different time-constants and mathematically reconstructing the true gas temperature from the resulting signals. Such a technique has been applied in gas turbine, rocket motor and combustion research. A new reconstruction technique based on difference equations has been developed and its effectiveness proven theoretically. The algorithms have been successfully tested and proven on experimental data from a rig that produces cyclic temperature variations. These tests highlighted that the separation of the thermocouple junctions must be very small to ensure that both sensors are subjected to the same gas temperatures. Exhaust gas temperatures were recorded by an array of thermocouples during transient operation of a high performance two-stroke engine. The results show that the increase in bandwidth arising from the dual sensor technique allowed accurate measurement of exhaust gas temperature with relatively robust thermocouples. Finally, an array of very fine thermocouples (12.5 - 50 microns) was used to measure the in-cycle temperature variation in the exhaust.

Fault Diagnostics for Internal Combustion Engines – Current and Future Techniques

The adoption of each new level of automotive emissions legislation often requires the introduction of additional emissions reduction techniques or the development of existing emissions control systems. This, in turn, usually requires the implementation of new sensors and hardware which must subsequently be monitored by the on-board fault detection systems. The reliable detection and diagnosis of faults in these systems or sensors, which result in the tailpipe emissions rising above the progressively lower failure thresholds, provides enormous challenges for OBD engineers. This paper gives a review of the field of fault detection and diagnostics as used in the automotive industry. Previous work is discussed and particular emphasis is placed on the various strategies and techniques employed. Methodologies such as state estimation, parity equations and parameter estimation are explained with their application within a physical model diagnostic structure. The utilization of symptoms and residuals in the diagnostic process is also discussed. These traditional physical model based diagnostics are investigated in terms of their limitations. The requirements from the OBD legislation are also addressed. Additionally, novel diagnostic techniques, such as principal component analysis (PCA) are also presented as a potential method of achieving the monitoring requirements of current and future OBD legislation.

Implementation of fractional-order electromagnetic potential through a genetic algorithm

Several phenomena present in electrical systems motivated the development of comprehensive models based on the theory of fractional calculus (FC). Bearing these ideas in mind, in this work are applied the FC concepts to define, and to evaluate, the electrical potential of fractional order, based in a genetic algorithm optimization scheme. The feasibility and the convergence of the proposed method are evaluated.

Quadros Elétricos Inteligentes-Smart Panels

Na sociedade atual, a preocupação com o ambiente, por um lado, e com o conforto e a segurança, por outro, faz com que a sustentabilidade energética se assuma como uma forma de intervenção adequada às exigências de qualidade de vida e à eficiência no âmbito da economia. Nesta conformidade, é incontornável a mais-valia do Smart Panel, um quadro elétrico inteligente criado com vista à consecução daqueles desideratos, o que motivou o tema do presente trabalho. Assim, pretende-se demonstrar as potencialidades do Smart Panel, um novo conceito de quadro elétrico que visa a otimização da sua funcionalidade na gestão dinâmica e pragmática das instalações elétricas, nomeadamente no que respeita ao controlo, monitorização e atuação sobre os dispositivos, quer in loco quer, sobretudo, à distância. Para a consecução deste objetivo, concorrem outros que o potenciam, designadamente a compreensão do funcionamento do quadro elétrico (QE) tradicional, a comparação deste com o Smart Panel e a demonstração das vantagens da utilização desta nova tecnologia. A grande finalidade do trabalho desenvolvido é, por um lado, colocar a formação académica ao serviço de um bom desempenho profissional futuro, por outro ir ao encontro da tendência tecnológica inerente às necessidades que o homem, hoje, tem de controlar. Deste modo, num primeiro momento, é feita uma abordagem geral ao quadro eléctrico tradicional a fim de ser compreendido o seu funcionamento, aplicações e potencialidades. Para tanto, a explanação inclui a apresentação de conceitos teóricos subjacentes à conceção, produção e montagem do QE. São explicitados os diversos componentes que o integram e funções que desempenham, bem como as interações que estabelecem entre si e os normativos a que devem obedecer, para conformidade. Houve a preocupação de incluir imagens coadjuvantes das explicações, descrições e procedimentos técnicos. No terceiro capítulo é abordada a tecnologia Smart Panel, introduzindo o conceito e objetivos que lhe subjazem. Explicita-se o modo de funcionamento deste sistema que agrupa proteção, supervisão, controlo, armazenamento e manutenção preventiva, e demonstra-se de que forma a capacidade de leitura de dados, de comunicação e de comando do quadro elétrico à distância se afigura uma revolução tecnológica facilitadora do cumprimento das necessidades de segurança, conforto e economia da vida moderna. Os capítulos quarto, quinto e sexto versam uma componente prática do trabalho. No capítulo quarto é explanado um suporte formativo e posterior demonstração do kit de ensaio, que servirá de apoio à apresentação da tecnologia Smart Panel aos clientes. Além deste suporte de formação, no quinto capítulo é elaborada uma lista de procedimentos de verificação a serem executados aos componentes de comunicação que integram o Smart Panel, para fornecimento ao quadrista. Por fim, no sexto capítulo incluem-se dois casos de estudo: o estudo A centra-se na aplicação da tecnologia Smart Panel ao projeto de um QE tradicional, que implica fazer o levantamento de toda a aparelhagem existente e, de seguida, proceder à transposição para a tecnologia Smart Panel por forma a cumprir os requisitos estabelecidos pelo cliente. O estudo de caso B consiste na elaboração de um projeto de um quadro eléctrico com a tecnologia Smart Panel em função de determinados requisitos e necessidades do cliente, por forma a garantir as funções desejadas.

Passive Solar Building Design Using Genetic Programming

Passive solar building design is the process of designing a building while considering sunlight exposure for receiving heat in winter and rejecting heat in summer. The main goal of a passive solar building design is to remove or reduce the need of mechanical and electrical systems for cooling and heating, and therefore saving energy costs and reducing environmental impact. This research will use evolutionary computation to design passive solar buildings. Evolutionary design is used in many research projects to build 3D models for structures automatically. In this research, we use a mixture of split grammar and string-rewriting for generating new 3D structures. To evaluate energy costs, the EnergyPlus system is used. This is a comprehensive building energy simulation system, which will be used alongside the genetic programming system. In addition, genetic programming will also consider other design and geometry characteristics of the building as search objectives, for example, window placement, building shape, size, and complexity. In passive solar designs, reducing energy that is needed for cooling and heating are two objectives of interest. Experiments show that smaller buildings with no windows and skylights are the most energy efficient models. Window heat gain is another objective used to encourage models to have windows. In addition, window and volume based objectives are tried. To examine the impact of environment on designs, experiments are run on five different geographic locations. Also, both single floor models and multi-floor models are examined in this research. According to the experiments, solutions from the experiments were consistent with respect to materials, sizes, and appearance, and satisfied problem constraints in all instances.

Obtenção de uma porcelana dielétrica a partir de matérias-primas do Rio Grande do Norte

The dielectric porcelain is usually obtained by mixing various raw materials proportions and is used in the production of electronic equipment for various applications, from capacitors of high and low Power to insulators for low, medium, high and extra high voltage, which are used in distribution lines and transmission of electricity.This work was directed to the s tudy of technological properties of technic porcelain, made from raw materials extracted from pegmatites found in the regions of Seridó and the Alto Oeste of Rio Grande do Norte, which are made of kaolin, quartz and feldspar, abundant and high quality in these regions. The technic ceramics were obtained by mixing in appropriate levels, kaolin, feldspar, quartz and clay, the last item from a pottery in the city of Sao Gonçalo do Amarante, Rio Grande do Norte. During the development the following characterizations correlated to raw materials were made: laser particle sizing, x-ray diffraction, DTA and TG. The compositions studied were formed by uniaxial pressing at a pressure of 50 MPa and sintered at temperatures ranging from 1150 to 1350ºC and levels (times) of sintering between 30, 60, 90 and 120 minutes. The characterization of the samples were taken from the analysis of weight loss, linear shrinkage, porosity, stoneware curve, bulk density, flexural strength of three points, SEM and X-ray diffraction, TMA, Dielectric and cross Resistivity. The studied materials can be employed in producing the objects used in electrical engineering such as: insulators for low, medium and high-voltage electrical systems, command devices, bushing insulation for transformers, power capacitors, spark plugs, receptacles for fluorescent and incandescent light bulbs and others

Dedução de Funções de Alívio para Priorização de Variantes de Chaveamento Adequadas à Eliminação de Sobrecargas

Eventually, violations of voltage limits at buses or admissible loadings of transmission lines and/or power transformers may occur by the power system operation. If violations are detected in the supervision process, corrective measures may be carried out in order to eliminate them or to reduce their intensity. Loading restriction is an extreme solution and should only be adopted as the last control action. Previous researches have shown that it is possible to control constraints in electrical systems by changing the network topology, using the technique named Corrective Switching, which requires no additional costs. In previous works, the proposed calculations for verifying the ability of a switching variant in eliminating an overload in a specific branch were based on network reduction or heuristic analysis. The purpose of this work is to develop analytical derivation of linear equations to estimate current changes in a specific branch (due to switching measures) by means of few calculations. For bus-bar coupling, derivations will be based on short-circuit theory and Relief Function methodology. For bus-bar splitting, a Relief Function will be derived based on a technique of equivalent circuit. Although systems of linear equations are used to substantiate deductions, its formal solution for each variant, in real time does not become necessary. A priority list of promising variants is then assigned for final check by an exact load flow calculation and a transient analysis using ATP Alternative Transient Program. At last, results obtained by simulation in networks with different features will be presented

Interior point algorithm for linear programming used in transmission network synthesis

This article presents a well-known interior point method (IPM) used to solve problems of linear programming that appear as sub-problems in the solution of the long-term transmission network expansion planning problem. The linear programming problem appears when the transportation model is used, and when there is the intention to solve the planning problem using a constructive heuristic algorithm (CHA), ora branch-and-bound algorithm. This paper shows the application of the IPM in a CHA. A good performance of the IPM was obtained, and then it can be used as tool inside algorithm, used to solve the planning problem. Illustrative tests are shown, using electrical systems known in the specialized literature. (C) 2005 Elsevier B.V. All rights reserved.