Short-duration voltage variations are disturbances of great concern, in the context of power quality. The permanent monitoring of these events is important because they are unpredictable and cause high economic losses to consumers. The strategic placement of power quality monitors has been studied, aiming, mostly, to reduce the installation cost of this monitoring system. However, it is more important not just monitoring these disturbances, but also identify their sources. This paper proposes a multi-objective approach, aiming, besides to reduce the cost also provide a meter allocation in favor of the location of the disturbance source. The optimization model proposed is solved by means of the Algorithm for Bicriteria Discrete Optimization and applied in IEEE 13 bus distribution test system. Several options of monitoring systems were obtained, respecting various constraints that influence decision making.

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Given the possibilities provided by smart grids in terms of communication infrastructure and information acquisition, there are new options on how to use the signals coming from meters to locate short circuits that occur in the system. This paper presents a framework for fault location in radial distribution systems based on machine learning algorithms and a multistage approach. A methodology in order to segment the system for proper identification of the outage region is presented. Studies are carried out involving the variation of the fault impedance, the fault incidence angle and the number and position of the meters. The IEEE 34-bus bar distribution feeder was considered for the tests. The results so far are promising, attesting and validating the presented methodology.

Resumo: Este trabalho apresenta uma abordagem para o problema da estimação de componentes harmônicas presente nos sistemas elétricos de potência, utilizando algoritmos evolutivos. Os dados de referência para o trabalho foram obtidos por meio do software Alternative Transients Program (ATP). Foram aplicados o algoritmo genético compacto e o algoritmo genético simples para estimar os parâmetros a fim de obter uma onda o mais próximo possível da onda fornecida pelo ATP. Os resultados obtidos com os algoritmos evolutivos citados são comparados entre si, em diversos cená-rios, e com os valores obtidos com a onda de referência gerada pelo software ATP. As comparações foram feitas com o intuito de evidenciar qual algoritmo resolve o problema exposto para uma aplicação dispondo de recursos computacionais limitados. Com base nos resultados, verificou-se que o algoritmo genético compacto resolve de forma satisfatória o problema proposto, sendo o CGA mais indicado que o SGA em situações que necessitam de um menor esforço computacional.Palavras-chave: Algoritmo genético compacto. Algoritmo genético simples. Harmônicas. Sistemas elétricos de potência. Abstract:The following work presents an approach for the harmonic components estimation problem, present on electrical power systems, by making use of evolutionary algorithms. The referential data was obtained by the alternative transients program (ATP) software. Compact and simple genetic algorithms where then applied to estimate the parameters to generate a wave as similar as possible to the one provided by the ATP software. The results yielded by the aforementioned evolutionary algorithms were then compared with one another in a number of scenarios, and using the values obtained by the wave of reference generated by the ATP software. The comparisons were used to seek evidence of which algorithm solved the problem, in a setting with limited availability of computational resources. Based on the generated results, it has been found that the Compact Genetic Algorithm satisfactorily solves the proposed problem, and it is the most indicated method, for when less computational effort is required.Keywords: Compact genetic algorithm. Electrical power systems. Harmonics. Simple genetic algorithm. IntroduçãoIdealmente, os sistemas elétricos de potência (SEPs) devem apresentar uma rede simétrica [1] e operar com forma de onda da tensão e corrente o mais próximo possível de uma senoide, contendo magnitude constante, bem como a frequência de 60Hz ± 0.5Hz. Porém, essa situação nem sempre é encontrada, o que implica na ocorrência de distúrbios na qualidade da energia elétrica (QEE) [2]. Os problemas na QEE estão associados a qualquer distúrbio manifestado na tensão, corrente ou desvio de frequência que resulte em falha ou operação indevida dos 1 UESPI, Campus Poeta Torquato Neto -Piauí (PI) -Brasil. {andreluissilvapessoa,ulissesph,hermesmanoel@gmail.com} 2 UFPI, Campus Ministro Petrônio Portella -Piauí (PI) -Brasil.

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