Browsing by Issue Date, starting with "2015-03-06"
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- Reliability of distribution networks with microgridsPublication . Costa, Paulo Moisés; Matos, ManuelThe emergence of micro-generation as a technically sound alternative has lead, in recent times, to the concept of micro grid, a network of LV consumers and producers able to export electric energy in some circumstances and also to work in a isolated way in emergency situations. Research work about the organization of micro grids, control devices, functionalities and other technical and economic aspects is presently being carried out, in order to establish a consistent technical framework to support the concept. Among other aspects, the effect of micro grids in the reliability of the distribution network has been pointed out as an important advantage, due to the ability of isolated operation in emergency situations. In order to address this topic, the present paper identifies the situations where the existence of a micro grid may reduce the interruption rate and time and thus improve the reliability indices of the distribution network. The relevant expressions necessary to quantify the reliability are also presented. An illustrative example is included, where the global influence of the micro grid in reliability is commented.
- Loss allocation in distribution networks with embedded generationPublication . Costa, Paulo Moisés; Matos, ManuelThis paper addresses the allocation of electrical losses in distribution networks with embedded generation, in a liberalized environment. The nonlinear nature of the issue, the loss changes due to voltage variation and, specially, the contribution of embedded generation to loss variation are considered. The proposed method is based on tracing the real and imaginary parts of the currents and has two steps. First, the losses in the distribution network, in the absence of embedded generation, are allocated to the consumers (or their providers). Second, the variations in the losses that result from the influence of embedded generation are allocated to the generators. These variations are a measure of the avoided or added costs related to losses. In the allocation process, made in a branch basis, both real and reactive powers are considered. The methodology presented in this paper can be used to evaluate embedded generation incentives or to design tariffs for the use of the distribution network.
- Economic Analysis of Microgrids Including Reliability AspectsPublication . Costa, Paulo Moisés; Manuel, MatosRecently, the new concept of microgrid (muG) has been emerging on distribution networks as a way to ease the integration of micro generation in LV networks and increase reliability. A muG is an association of a low voltage distribution network, small modular generation systems (micro-generators), loads and storage devices having some local coordinated functions. This entity can operate in two different modes: interconnected or emergency. In the first mode, the microgrid is connected with the distribution network, importing or exporting electricity and/or ancillary services. When in emergency mode, the microgrid operates isolated from the distribution network and uses local resources, changing from power control to frequency control and, if necessary, shedding load. A micro grid will only be established if its promoters achieve sufficient advantages that justify the incurred costs, namely the investment, operation and maintenance costs. The main purpose of this paper is to identify all the relevant costs and benefits and build a decision model for the situation, taking into account the regulatory framework, which is essential for the definition of some of the benefits. The paper also shows how to include in the evaluation the risk associated to the uncertainties in data and parameters. An illustrative example is included that shows a possible situation of equilibrium between global costs and benefits
- Representação social dos especialistas em enfermagem de reabilitação : implicações nos processos de contratualizaçãoPublication . Amaro, Rodrigo Miguel Marques; Albuquerque, Carlos Manuel SousaEnquadramento: A contratualização de Enfermeiros Especialistas em Reabilitação tem sido descurada ao longos dos últimos anos em Portugal. A alegação deste facto, por parte dos gestores é fugaz, tendo em conta o impacto positivo nos indicadores de saúde permanente, por parte daqueles profissionais. Este estudo teve como objetivo: compreender se a contratualização dos enfermeiros especialistas em reabilitação pode ser mediada pela Representação Social destes, quando argumentada pelos enfermeiros gestores. Método: Foi desenvolvido um estudo de investigação de natureza qualitativa, com metodologia assente na Grounded Theory. A amostra foram os Enfermeiros Gestores de duas unidades de saúde portuguesas. Como técnica de colheita de dados recorreu-se à entrevista semiestruturada aplicada a doze participantes. A análise de dados recorreu à grounded analysis. Resultados: Resultaram da codificação axial quatro subcategorias principais: Contratualização de Enfermeiros Especialistas em Reabilitação, Enfermeiros Especialistas, Enfermeiros Especialistas em Reabilitação e Gestão de Enfermeiros que culminaram na codificação seletiva, com a categoria central: Representação Social dos Enfermeiros Especialistas em Reabilitação. Os Enfermeiros Gestores reconhecem a necessidade de contratualização, apresentando argumentos que assentam na descrição detalhada da especialidade de reabilitação e dos seus benefícios para os clientes (Representação Social). No entanto, relatam constrangimentos económicos que impedem a contratualização e minimizam a argumentação relativa à Representação Social dos Especialistas em Reabilitação focada no cliente. Conclusões: Admitimos que Representação Social dos Especialistas em Enfermagem de Reabilitação é uma forte argumentação a ser utilizada pelos Enfermeiros Gestores, pois assenta numa realidade factual que descreve de forma precisa e eloquente aqueles profissionais, podendo vir a influenciar positivamente a sua contratualização. Confrontando objetivamente o principal pseudo-obstáculo - fator económico. Para tal, é necessário dotar os Enfermeiros Gestores de formação adequada e consistente pelas Organizações tutoras da Enfermagem Portuguesa. Palavras chave: Enfermagem de Reabilitação; Gestores de Enfermagem; Representação Social; Grounded Analysis.