ABSTRACT
Abstract Microgrids (MGs) have increasingly attracted the attention of researchers, government officials, and electricity companies for the values and services they can add to the grid. They can operate independently as a single controllable unit in a coordinated way while connected or islanded, which make them suitable to integrate the growing amount of distributed energy resources (DERs) into the distribution network (DN). An active distribution network with high penetration of DERs could be redefined into a collection of microgrids in different layers, pooling their resources together to enhance the grid's performance in the sense of electricity as a service. However, enabling a microgrid-based power system infrastructure poses challenges concerning operation and control. In this paper, a comprehensive overview of research topics regarding microgrid operation are shown in a hierarchical or stratified manner, looking for a holistic vision of a microgrid-based distribution system. First, multi-objective optimization within one microgrid is formulated aiming to minimize costs and maximize battery life is presented. Second, the interaction among MGs, DERs and the DN was modeled using the OPF technique to represent the operation of the grid as a whole. Following, a methodology for collaborative optimization of multiple MGs operating together is presented and at last a theoretical framework for MG operation through decentralized energy markets is discussed. As a result, this paper aims to contribute to a broad vision of the distribution system based on microgrid operation in all its levels.
Subject(s)
Politics , Electric Wiring , Energy Supply , BrazilABSTRACT
RESUMO Em sistemas de distribuição de água, economia de energia elétrica pode ser alcançada pela substituição de bombas de rotação constante por bombas de rotação variável (BRV). Os elevados custos de instalação e operação de BRV requerem uma avaliação econômica prévia do projeto, a qual geralmente é acompanhada do uso de simuladores para análises hidráulicas do sistema. Um dos programas mais utilizados para esse fim é o EPANET 2, que é impreciso para computar a eficiência de BRV, pois o programa não leva em conta a mudança na curva de eficiência da bomba quando sua velocidade de rotação é alterada. Neste trabalho, uma rotina para o cálculo da eficiência de BRV, baseada em metodologia da literatura, foi implementada no código-fonte do EPANET 2. A influência da nova rotina nos resultados previstos pelo programa para eficiência, potência e consumo de energia de BRV foi avaliada em simulações com uma rede hipotética. Os resultados mostram que a versão original do EPANET 2 tende a subestimar a eficiência e, consequentemente, superestimar a potência e o consumo de energia de BRV. A versão modificada do EPANET 2 proporciona uma melhor previsão do comportamento de BRV e, portanto, o seu uso é recomendado na simulação de redes de distribuição de água equipadas com BRV.
ABSTRACT In water distribution systems, energy savings can be achieved by substituting fixed-speed pumps by variable-speed pumps (VSP). The high costs of installation and operation of VSP require a preliminary economic assessment of the project, which is usually complemented by the use of a computer simulation software for hydraulic analyses of the system. One of the most used software programs for this purpose is EPANET 2, which is inaccurate when computing VSP efficiency. This is because the software does not take into account the changes in the pump efficiency curve when the pump speed is changed. In this study, a routine for calculating VSP efficiency, based on literature methodology, was implemented in the source code of EPANET 2. The influence of the new routine on the results predicted by the software for efficiency, power and energy consumption of VSP was evaluated in simulations with a hypothetical network. The results show that the original version of EPANET 2 tends to underestimate the efficiency and thus overestimate the power and energy consumption of VSP. The modified version of EPANET 2 provides a better prediction of VSP behavior; thus, its use is recommended in the simulation of water distribution networks equipped with VSP.
ABSTRACT
RESUMO: O presente trabalho teve por objetivos determinar a rugosidade relativa dos tubos de PVC e avaliar a sua influência no dimensionamento das redes de distribuição de água, segundo as exigências das NBR 5647-1:2004 e 5647-3:1999. As avaliações foram realizadas para três amostras de tubulações novas de DN 50, 75 e 100 e testemunhos em duplicata de DN 50 e 75, extraídos de campo após 10 e 34 anos de uso, respectivamente. Nas tubulações novas, a rugosidade relativa variou de 5,416 E-05±0,834 E-5 a 6,125 E-4±0,756 E-4. Já para as usadas, ela se alterou de 4,853 E-04±3,221 E-4 a 1,056 E-03±0,419 E-3. Essas rugosidades relativas não influenciaram a determinação do fator de atrito quando calculado pela fórmula de Swamee-Jain.
ABSTRACT: This study aimed at determining the relative roughness of PVC pipes and evaluating its influence on dimensioning the water distribution networks, according to the requirements of the Brazilian regulations NBR 5647-1:2004 and 5647-3:1999. The evaluations were conducted for three samples of new pipes of DN 50, 75 and 100, besides double testimonies of DN 50 and 75, which were taken from the field after 10 and 34 years of use, respectively. In the new pipes, the relative roughness ranged from 5.416 E-05±0.834 E-5 to 6.125 E-4±0.756 E-4. The used pipes ranged from 4.853 E-04±3.221 E-4 to 1.056 E-03±0.419 E-3. These amounts of relative roughness did not influence the friction factor determination when calculated through Swamee-Jain equation.
ABSTRACT
La presente revisión tuvo como propósito analizar las estrategias para el control de la contaminación debida a la formación de la corrosión e incrustaciones, basado en los factores que afectan el deterioro de los sistemas de distribución de agua potable, así como, su influencia sobre la calidad del agua suministrada al consumidor. Los sistemas de distribución pueden afectar la calidad del agua potable debido a las condiciones de la tubería y a la operación del sistema. La corrosión, las incrustaciones y los depósitos en la red de distribución, son otros de los problemas con mayor importancia en la industria del agua potable; esto puede afectar a la salud, la aceptación pública del suministro de agua y el costo de proveer un agua digna de confianza. Se concluye y se recomienda que como estrategias para controlar la corrosión y la formación de incrustaciones se deben seleccionar apropiadamente los materiales y el diseño del sistema, realizar el tratamiento químico adecuado (ajuste de pH, alcalinidad, oxigeno, uso de inhibidores de corrosión) y usar revestimientos y pinturas resistentes a la corrosión para proteger las paredes de las tuberías.
The aim of this review was to analyze control strategies of contamination caused by the formation of corrosion and incrustations based on factors affecting deterioration of distribution systems of potable water as well as its influence on the quality of water supplied to the consumer. Distribution systems can affect the quality of drinking water due to the conditions of the pipes and the systems operation. Corrosion, incrustations, and deposits in the distribution network major problems in the drinking water industry. These may affect health, public acceptance of the water supply and the cost of supplying reliable water. We conclude and recommend that, in order to control corrosion and the formation of incrustations, one must select appropriate materials and a sound system design, apply proper chemical treatment (adjusting pH, alkalinity, oxygen, the use of corrosion inhibitors) and use coatings and paints resistant to corrosion in order to protect the walls of the pipes.