Modelagem e análise dinâmica de um sistema de conversão de energia eólica dotado de gerador síncrono de imã permanente utilizando a plataforma ATP

Human development requires a broad balance between ecological, social and economic factors in order to ensure its own sustainability. In this sense, the search for new sources of energy generation, with low deployment and operation costs, which cause the least possible impact to the environment, has been the focus of attention of all society segments. To do so, the reduction in exploration of fossil fuels and the encouragement of using renewable energy resources for distributed generation have proved interesting alternatives to the expansion of the energy matrix of various countries in the world. In this sense, the wind energy has acquired an increasingly significant role, presenting increasing rates of power grid penetration and highlighting technological innovations such as the use of permanent magnet synchronous generators (PMSG). In Brazil, this fact has also been noted and, as a result, the impact of the inclusion of this source in the distribution and sub-transmission power grid has been a major concern of utilities and agents connected to Brazilian electrical sector. Thus, it is relevant the development of appropriate computational tools that allow detailed predictive studies about the dynamic behavior of wind farms, either operating with isolated load, either connected to the main grid, taking also into account the implementation of control strategies for active/reactive power generation and the keeping of adequate levels of voltage and frequency. This work fits in this context since it comprises mathematical and computational developments of a complete wind energy conversion system (WECS) endowed with PMSG using time domain techniques of Alternative Transients Program (ATP), which prides itself a recognized reputation by scientific and academic communities as well as by electricity professionals in Brazil and elsewhere. The modeling procedures performed allowed the elaboration of blocks representing each of the elements of a real WECS, comprising the primary source (the wind), the wind turbine, the PMSG, the frequency converter, the step up transformer, the load composition and the power grid equivalent. Special attention is also given to the implementation of wind turbine control techniques, mainly the pitch control responsible for keeping the generator under the maximum power operation point, and the vector theory that aims at adjusting the active/reactive power flow between the wind turbine and the power grid. Several simulations are performed to investigate the dynamic behavior of the wind farm when subjected to different operating conditions and/or on the occurrence of wind intensity variations. The results have shown the effectiveness of both mathematical and computational modeling developed for the wind turbine and the associated controls.

Cidades saudáveis e qualidade de vida em Uberlândia (MG): aportes metodológicos para um processo em construção

The current study includes theoretical and methodological reflections on the quality of life in the city of Uberlândia, Minas Gerais. It started from the thought that the quality of life is multifactorial and is permanently under construction and the main objective of analyzing it as one of the componets of Healthy Cities's moviment. The theoretical research focused on the concepts of healthy cities, quality of life, health, sustainability, well-being, happiness, indexes and indicators. From the use of multiple search strategies, documentary and on field of quantitative and qualitative character, this research of exploratory descriptive nature can offers a contribution to the studies on the quality of life in cities. It is proposed that the studies startes to work with some concept, like some notions os life quality adequated for some paticular reality, whose notions can approach concepts already established as health. This step is important on the exploratory researches. The studies may include aspects of objective analysis, subjective or both. The objective dimension, which is most common approach, are traditionally considered variables and indicators related to: the urban infrastructure (health, education, leisure, security, mobility), dwelling (quantitative and qualitative dwlling deficit), the urban structure (density and mix uses), socioeconomic characteristics (age, income, education), urban infrastructure (sanitation, communication), governance (social mobilization and participation). To focus on the subjective dimension, most recent and unusual, it is proposed to consider the (dis)satisfaction, the personal assessment in relation to the objective aspects. In conclusion, being intrinsically related to the health, the quality of life also has a number of determinants, and the ideal of the reach of quality of life depends on the action of all citizens based on the recognition of networks and territories, in a interescalar perspective and intersectoral. Therefore, emphasis in given on the potential of tools, such as the observatories, to monitor and intervent in reality, aiming in a building process of healthy cities.

Avaliação de sustentabilidade ambiental do sistema de abastecimento de água e esgotamento sanitário de Uberaba - MG

This paper analyses the sustainability under the environmental (ecological) perspective of Water Supply and Sanitary Sewers Systems from Uberaba city, MG. It was accomplished in this analysis, An Environmental Sustainability Assessment of those systems, by the means of specific sustainability indicators proposed for Uberaba, but which may be used for other simi-lar cities. To the characterization of the systems, visitations were made to the main units as well as a documental was elaborated. The definition of the level or stage of the sustainability by the indicators was made based on a literature review, on interviews with the technicians and managers of the systems and based on the characterization and observation of the system reality, being attributed to them the following classification: Non Sustainable, Low Sustaina-bility, Medium Sustainability and High Sustainability. It was verified that the indicators that have lower compatibility to the process of sustainability to the studied systems are those rela-ted to the water physical losses, to the water per capita consumption, to the electricity con-sumption and to the sludge from the water treatment plants disposal untreated into a water body, for the Water Supply System. And those ones related to the attendance with sewage treatment, to the electricity consumption and to the usage of the treated sewage, for the Sani-tary Sewers, all of them classified as Non Sustainable.