Revisão do plano de segurança da água do sistema regional do Carvoeiro

Os Planos de Segurança da Água surgem com a necessidade de aumentar a segurança da água de abastecimento, superando a monitorização de conformidade de “fim de linha”, permitindo aumentar a confiança do consumidor na qualidade da água que lhe é fornecida. Esta nova abordagem recorre a uma metodologia de gestão baseada na identificação e no controlo de riscos em pontos críticos de um sistema de abastecimento, em complemento do controlo realizado através da monitorização da conformidade da água entregue aos consumidores. O Plano de Segurança da Água (PSA) encontra-se implementado no Sistema Regional do Carvoeiro (SRC) desde o ano de 2009. O SRC é um sistema de abastecimento de água em alta, sendo constituído por conjunto de infraestruturas de captação, tratamento, transporte e armazenamento de água desde a sua origem, localizada no rio Vouga, em Carvoeiro, até aos municípios integrados na Associação de Municípios do Carvoeiro-Vouga. Atendendo à obra de expansão do SRC, tornou-se imperativo efetuar uma revisão ao PSA, sendo este o objetivo primordial do trabalho de estágio desenvolvido na empresa Águas do Vouga S.A, concessionária responsável pela gestão do SRC. Para a prossecução deste objetivo, o trabalho desenvolvido envolveu os seguintes passos metodológicos: identificação das operações aplicadas no SRC; identificação de perigos e eventos perigosos em todos os órgãos constituintes do sistema; avaliação de riscos; identificação de pontos críticos de controlo; identificação de pontos de monitorização e medidas preventivas; elaboração do plano de monitorização, incluindo, procedimentos de controlo operacional em condições normais de funcionamento e em caso de desvio; validação deste plano. Deste trabalho resultou a identificação de 166 eventos perigosos, 17 tipologias de perigos, 3 pontos de controlo crítico e 17 pontos de monitorização. Os pontos de controlo crítico foram identificados nos processos de tratamento da ETA do Carvoeiro. O primeiro foi localizado na etapa de filtração com areia, antracite e zeólitos correspondendo aos perigos com metais (Fe e Mn), outros compostos químicos perigosos, partículas, turvação, matéria orgânica e alumínio. O segundo ponto foi identificado na etapa de filtração com filtros de carvão ativado granular relativo ao aparecimento de sabor e cianotoxinas. O terceiro ponto de controlo crítico foi encontrado na etapa de desinfeção referente aos microrganismos patogénicos. Os pontos de monitorização foram localizados ao longo do sistema em situações onde não se dispõem de nenhuma medida de controlo para eliminar o perigo e antes e após os pontos de controlo crítico. O plano de monitorização foi desenvolvido para estes pontos, embora os limites e procedimentos definidos devam ser alvo de revisão após a conclusão da obra de expansão do sistema. A validação da revisão do plano foi iniciada, mas cingiu-se apenas na avaliação preliminar de riscos, prévia ao início de operação da ETA do Carvoeiro. Para além da revisão deste plano, foram realizadas outras tarefas, nomeadamente uma análise à qualidade da água fornecida e distribuída pelo sistema, a elaboração do plano PCQA para o ano de 2016, a configuração da plataforma de gestão operacional NAVIATM e a revisão do Manual de Gestão da Águas do Vouga relativo ao processo de qualidade na captação, tratamento e distribuição e ao processo de qualidade na gestão do PSA.

Estágio profissional em gabinete de engenharia, na componente de climatização

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecânica com Especialização em Energia, Climatização e Refrigeração

A framework for better understanding drinking-water quality in Happy Valley-Goose Bay, Labrador: Implications for optimization and protection of municipally supplied water

This research project was driven by the recurring complaints and concerns voiced in the media by residents living in the Valley area of the community of Happy Valley-Goose Bay, Labrador. Drinking water in this town is supplied by two water treatment plants (a municipality treatment plant and a DND treatment plant), which use raw water from two different sources (groundwater from multiple wells versus surface water from Spring Gulch brook) and use two different processes of drinking-water treatment. In fact, the drinking water supplied in the Valley area has a unique distribution arrangement. To meet demand, the Valley area is served by a blend of treated waters from a storage reservoir (Sandhill reservoir), which is fed by both water treatment plants. Most of the time, treated water from the municipal treatment plant dominates in the mixture. As water travels through the distribution system and household plumbing, specific reactions can occur either in the water itself and/or at the solid–liquid interface at the pipe walls; this is strongly influenced by the physical and chemical characteristics of the water. These reactions can introduce undesirable chemical compounds and/or favor the growth of bacteria in the drinking water, causing the deterioration of the quality of water reaching the consumer taps. In the distribution system in general, these chemical constituents and bacteria may pose potential threats to health or the water’s aesthetic qualities (smell, taste or appearance). Drinking water should be not only safe, but also palatable.

AIR SIDE HEAT TRANSFER ENHANCEMENT IN HEAT EXCHANGERS UTILIZING INNOVATIVE DESIGNS AND THE ADDITIVE MANUFACTURING TECHNIQUE

Over the last decade, rapid development of additive manufacturing techniques has allowed the fabrication of innovative and complex designs. One field that can benefit from such technology is heat exchanger fabrication, as heat exchanger design has become more and more complex due to the demand for higher performance particularly on the air side of the heat exchanger. By employing the additive manufacturing, a heat exchanger design was successfully realized, which otherwise would have been very difficult to fabricate using conventional fabrication technologies. In this dissertation, additive manufacturing technique was implemented to fabricate an advanced design which focused on a combination of heat transfer surface and fluid distribution system. Although the application selected in this dissertation is focused on power plant dry cooling applications, the results of this study can directly and indirectly benefit other sectors as well, as the air-side is often the limiting side for in liquid or single phase cooling applications. Two heat exchanger designs were studied. One was an advanced metallic heat exchanger based on manifold-microchannel technology and the other was a polymer heat exchanger based on utilization of prime surface technology. Polymer heat exchangers offer several advantages over metals such as antifouling, anticorrosion, lightweight and often less expensive than comparable metallic heat exchangers. A numerical modeling and optimization were performed to calculate a design that yield an optimum performance. The optimization results show that significant performance enhancement is noted compared to the conventional heat exchangers like wavy fins and plain plate fins. Thereafter, both heat exchangers were scaled down and fabricated using additive manufacturing and experimentally tested. The manifold-micro channel design demonstrated that despite some fabrication inaccuracies, compared to a conventional wavy-fin surface, 15% - 50% increase in heat transfer coefficient was possible for the same pressure drop value. In addition, if the fabrication inaccuracy can be eliminated, an even larger performance enhancement is predicted. Since metal based additive manufacturing is still in the developmental stage, it is anticipated that with further refinement of the manufacturing process in future designs, the fabrication accuracy can be improved. For the polymer heat exchanger, by fabricating a very thin wall heat exchanger (150μm), the wall thermal resistance, which usually becomes the limiting side for polymer heat exchanger, was calculated to account for only up to 3% of the total thermal resistance. A comparison of air-side heat transfer coefficient of the polymer heat exchanger with some of the commercially available plain plate fin surface heat exchangers show that polymer heat exchanger performance is equal or superior to plain plate fin surfaces. This shows the promising potential for polymer heat exchangers to compete with conventional metallic heat exchangers when an additive manufacturing-enabled fabrication is utilized. Major contributions of this study are as follows: (1) For the first time demonstrated the potential of additive manufacturing in metal printing of heat exchangers that benefit from a sophisticated design to yield a performance substantially above the respective conventional systems. Such heat exchangers cannot be fabricated with the conventional fabrication techniques. (2) For the first time demonstrated the potential of additive manufacturing to produce polymer heat exchangers that by design minimize the role of thermal conductivity and deliver a thermal performance equal or better that their respective metallic heat exchangers. In addition of other advantages of polymer over metal like antifouling, anticorrosion, and lightweight. Details of the work are documented in respective chapters of this thesis.

Arquitetura híbrida com DSP e FPGA para implementação de controladores de filtros ativos de potência

The presence of non-linear loads at a point in the distribution system may deform voltage waveform due to the consumption of non-sinusoidal currents. The use of active power filters allows significant reduction of the harmonic content in the supply current. However, the processing of digital control structures for these filters may require high performance hardware, particularly for reference currents calculation. This work describes the development of hardware structures with high processing capability for application in active power filters. In this sense, it considers an architecture that allows parallel processing using programmable logic devices. The developed structure uses a hybrid model using a DSP and an FPGA. The DSP is used for the acquisition of current and voltage signals, calculation of fundamental current related controllers and PWM generation. The FPGA is used for intensive signal processing, such as the harmonic compensators. In this way, from the experimental analysis, significant reductions of the processing time are achieved when compared to traditional approaches using only DSP. The experimental results validate the designed structure and these results are compared with other ones from architectures reported in the literature.

Experimental study on the impact of using a fan coil in the evaluation of contaminant removal effectiveness of common air diffusion strategies

Indoor Air 2016 - The 14th International Conference Indoor Air Quality and Climate

Real-time load-side control of electric power systems

Two trends are emerging from modern electric power systems: the growth of renewable (e.g., solar and wind) generation, and the integration of information technologies and advanced power electronics. The former introduces large, rapid, and random fluctuations in power supply, demand, frequency, and voltage, which become a major challenge for real-time operation of power systems. The latter creates a tremendous number of controllable intelligent endpoints such as smart buildings and appliances, electric vehicles, energy storage devices, and power electronic devices that can sense, compute, communicate, and actuate. Most of these endpoints are distributed on the load side of power systems, in contrast to traditional control resources such as centralized bulk generators. This thesis focuses on controlling power systems in real time, using these load side resources. Specifically, it studies two problems.

(1) Distributed load-side frequency control: We establish a mathematical framework to design distributed frequency control algorithms for flexible electric loads. In this framework, we formulate a category of optimization problems, called optimal load control (OLC), to incorporate the goals of frequency control, such as balancing power supply and demand, restoring frequency to its nominal value, restoring inter-area power flows, etc., in a way that minimizes total disutility for the loads to participate in frequency control by deviating from their nominal power usage. By exploiting distributed algorithms to solve OLC and analyzing convergence of these algorithms, we design distributed load-side controllers and prove stability of closed-loop power systems governed by these controllers. This general framework is adapted and applied to different types of power systems described by different models, or to achieve different levels of control goals under different operation scenarios. We first consider a dynamically coherent power system which can be equivalently modeled with a single synchronous machine. We then extend our framework to a multi-machine power network, where we consider primary and secondary frequency controls, linear and nonlinear power flow models, and the interactions between generator dynamics and load control.

(2) Two-timescale voltage control: The voltage of a power distribution system must be maintained closely around its nominal value in real time, even in the presence of highly volatile power supply or demand. For this purpose, we jointly control two types of reactive power sources: a capacitor operating at a slow timescale, and a power electronic device, such as a smart inverter or a D-STATCOM, operating at a fast timescale. Their control actions are solved from optimal power flow problems at two timescales. Specifically, the slow-timescale problem is a chance-constrained optimization, which minimizes power loss and regulates the voltage at the current time instant while limiting the probability of future voltage violations due to stochastic changes in power supply or demand. This control framework forms the basis of an optimal sizing problem, which determines the installation capacities of the control devices by minimizing the sum of power loss and capital cost. We develop computationally efficient heuristics to solve the optimal sizing problem and implement real-time control. Numerical experiments show that the proposed sizing and control schemes significantly improve the reliability of voltage control with a moderate increase in cost.

Evaluación técnica y económica para analizar la viabilidad del montacargas eléctrico en el sector productivo

Esta tesis pretende demostrar y describir las diferentes características de los montacargas que existen en el mercado, teniendo en cuenta sus ventajas y desventajas, logrando como objetivo analizar la viabilidad de la implementación de los montacargas eléctricos en la industria colombiana a partir de la información brindada sobre las características esenciales de los montacargas eléctricos que hay en el mercado. Así mismo, se quiere mostrar que los montacargas eléctricos generan un ahorro sustancial en comparación con los montacargas convencionales que hay hoy en día en el mercado, logrando así que la industria colombiana reduzca sus gastos en un porcentaje mediante la implementación de las nuevas referencias de montacargas eléctricos los cuales serian una alternativa para las compañías colombianas. Mediante una detallada revisión conceptual, se mostrara la viabilidad de los montacargas eléctricos frente a los otros tipos de montacargas, teniendo como premisa el conocimiento de lo que hoy en día requieren las industrias colombianas, y cumpliendo así con una detallada comparación en donde se enfatice la diferenciación de los montacargas eléctricos con otros tipos que existen y se logre brindar una clara percepción de estos junto con las ventajas de estos vehículos para lograr así brindar mayor información a la industria colombiana sobre las ventajas de la implementación de los montacargas eléctricos en la industria colombiana.

Operator's manual : Tactical Water Distribution Equipment System (TWDS) set 10-mile segment, model 06749-0183-81 (4320-01-122-3547), model 110-00-0000 (4320-01-168-0591), model 919 (4320-01-168-0590).

"14 April 1986."

Study of distribution network demand response events in the Portuguese system

In competitive electricity markets with deep concerns for the efficiency level, demand response programs gain considerable significance. As demand response levels have decreased after the introduction of competition in the power industry, new approaches are required to take full advantage of demand response opportunities. Grid operators and utilities are taking new initiatives, recognizing the value of demand response for grid reliability and for the enhancement of organized spot markets’ efficiency. This paper proposes a methodology for the selection of the consumers that participate in an event, which is the responsibility of the Portuguese transmission network operator. The proposed method is intended to be applied in the interruptibility service implemented in Portugal, in convergence with Spain, in the context of the Iberian electricity market. This method is based on the calculation of locational marginal prices (LMP) which are used to support the decision concerning the consumers to be schedule for participation. The proposed method has been computationally implemented and its application is illustrated in this paper using a 937 bus distribution network with more than 20,000 consumers.

Intuitionistic fuzzy Choquet integral operator-based approach for black-start decision-making

Determining the optimal of black-start strategies is very important for speeding the restoration speed of a power system after a global blackout. Most existing black-start decision-making methods are based on the assumption that all indexes are independent of each other, and little attention has been paid to the group decision-making method which is more reliable. Given this background, the intuitionistic fuzzy set and further intuitionistic fuzzy Choquet integral operator are presented, and a black-start decision-making method based on this integral operator is presented. Compared to existing methods, the proposed algorithm cannot only deal with the relevance among the indexes, but also overcome some shortcomings of the existing methods. Finally, an example is used to demonstrate the proposed method. © 2012 The Institution of Engineering and Technology.

Multi-agent systems for modeling high penetration photovoltaic system impacts in distribution networks

This paper reviews the use of multi-agent systems to model the impacts of high levels of photovoltaic (PV) system penetration in distribution networks and presents some preliminary data obtained from the Perth Solar City high penetration PV trial. The Perth Solar City trial consists of a low voltage distribution feeder supplying 75 customers where 29 consumers have roof top photovoltaic systems. Data is collected from smart meters at each consumer premises, from data loggers at the transformer low voltage (LV) side and from a nearby distribution network SCADA measurement point on the high voltage side (HV) side of the transformer. The data will be used to progressively develop MAS models.

Provisioning a 3.3 MW PhotoVoltaic generation system onto a distribution authority’s 11 kV rural feeder

This paper describes part of an engineering study that was undertaken to demonstrate that a multi-megawatt Photovoltaic (PV) generation system could be connected to a rural 11 kV feeder without creating power quality issues for other consumers. The paper concentrates solely on the voltage regulation aspect of the study as this was the most innovative part of the study. The study was carried out using the time-domain software package, PSCAD/EMTDC. The software model included real time data input of actual measured load and scaled PV generation data, along with real-time substation voltage regulator and PV inverter reactive power control. The outputs from the model plot real-time voltage, current and power variations throughout the daily load and PV generation variations. Other aspects of the study not described in the paper include the analysis of harmonics, voltage flicker, power factor, voltage unbalance and system losses.

Exploiting the beta distribution-based reputation model in recommender system

Reputation systems are employed to measure the quality of items on the Web. Incorporating accurate reputation scores in recommender systems is useful to provide more accurate recommendations as recommenders are agnostic to reputation. The ratings aggregation process is a vital component of a reputation system. Reputation models available do not consider statistical data in the rating aggregation process. This limitation can reduce the accuracy of generated reputation scores. In this paper, we propose a new reputation model that considers previously ignored statistical data. We compare our proposed model against state-of the-art models using top-N recommender system experiment.