ABSTRACT. The goal of the capacitor allocation problem in radial distribution networks is to minimize technical losses with consequential positive impacts on economic and environmental areas. The main objective is to define the size and location of the capacitors while considering load variations in a given horizon. The mathematical formulation for this planning problem is given by an integer nonlinear mathematical programming model that demands great computational effort to be solved. With the goal of solving this problem, this paper proposes a methodology that is composed of heuristics and Tabu Search procedures. The methodology presented explores network system characteristics of the network system reactive loads for identifying regions where procedures of local and intensive searches should be performed. A description of the proposed methodology and an analysis of computational results obtained which are based on several test systems including actual systems are presented. The solutions reached are as good as or better than those indicated by well referenced methodologies. The technique proposed is simple in its use and does not require calibrating an excessive amount of parameters, making it an attractive alternative for companies involved in the planning of radial distribution networks.
ResumoCom abordagem predominantemente financeira, alguns estudos realizados na última década propõem políticas para planejamento de produção de grãos em sistema de fazenda situado na planície de Paracatu, MG. Baseando-se nos aspectos agro-técnicos destes estudos, e levando-se em consideração a periodicidade mensal dos gastos e a existência de créditos de longo prazo para o setor, este trabalho define e expressa o problema de planejamento de produção agrícola como um modelo de programação linear inteiro-misto, onde tratamento dinâmico mensal é dado às atividades de produção e financeiras ao longo de um horizonte de dez anos e cinco meses. O modelo é aplicado a duas situações distintas, obtidas através da utilização de planos de créditos de longo e curto prazos para o setor agrícola no Brasil. Resultados e análise sobre a viabilidade sócio-econômica financeira deste sistema são apresentados.Palavras-chave: modelo de fazenda; planejamento de produção agrícola; programação linear.
AbstractDuring the last ten years, some studies with financial emphasis have proposed technical plan policies for a crop production farm system located on Paracatu-MG. Based on agro-technical aspects of those studies and considering financial aspects like: monthly expenses and long-term investments, the present article represents those production systems by means of a mixed integer dynamic linear mathematical programming model where monthly dynamic treatment and a planning horizon of ten years and five months are stated for production and financial activities. Considering recent government financial policies for farmers, the model is applied to two distinct situations derived from the use of short and long term loans for Brazilian agricultural sector. Scored results and an analysis on social-economic and financial feasibility of the system are also drawn.
Based on an agro-technical study for the mid-west region of Brazil, and considering financial conditions like monthly expenses and long-term investments, a mixed integer and dynamic linear model has been proposed for representing crop production systems. This model establishes a monthly dynamic treatment of production and financial activities over a long-term planning horizon for small and medium farm systems. In this paper, by considering more recent government financial policies for the Brazilian agricultural sector related to the Pronaf and Proger credit lines, a mathematical model is updated for distinct situations derived from the use of short and long-term loans which were defined for small and medium farmers. In this way, new versions of the original model are obtained by separately implementing into the production systems economic and financial conditions of credit lines for the years 2006 and 2009. Computational tests are performed and the results obtained are presented in several scenarios. Also, an evolutionary analysis on the socio-economic and financial feasibility of the agricultural farm system is drawn over the last decade by comparing the results obtained to one known from the year 2002.
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