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Resumo -Este artigo apresenta o projeto de um conversor boost com controle modo corrente média para mitigar afundamentos de tensão em acionamentos de velocidade variável (AVV). Com base em testes para obter a sensibilidade do AVV a afundamentos de tensão, o conversor boost foi projetado para aumentar a tolerância do AVV a afundamentos trifásicos de 0,7 p.u. e duração de 200 ms para 0,5 p.u. de qualquer duração. Testes recomendados pelo grupo de trabalho JWG C4.110 do CIGRE/CIRED/UIE foram realizados para validar a suportabilidade do sistema de acionamento que compreende conversor boost conectado ao AVV com alimentação compartilhada Os resultados comprovaram a eficácia do conversor projetado. Palavras-Chave -Acionamento de Velocidade Variável, Afundamento de Tensão, Conversor Boost, Suportabilidade a Afundamento de Tensão.Abstract -This paper presents the design of a boost converter with average current mode control to mitigate voltage sags in adjustable speed drives (ASD). Based on tests performed on the ASD to assess its tolerance to voltage sags, the boost converter was designed to increase the voltage ride-through of the ASD from 0.7 p.u. and 200 ms to 0.5 p.u. of any length. Tests recommended by the Working Group C4.110 sponsored by CIGRE/CIRED/UIE were performed to validate the voltage ride-through capability of the drive system comprising the boost converter connected to the ASD, both sharing the same power supply. The results have attested the efficiency of the converter designed.

Along with the restructuring of the power sector and the dissemination of the system automation and the information and communication technology, the power utilities have been encouraged to deliver more and more information to their consumers, grid operators and regulation agencies concerning the performance of the power system. This paper presents the application of protective digital relays to assist the power quality evaluation of a power system. Recommended power quality indices are used to measure the severity of short-duration voltage variation. The indices are calculated based on the registers of digital relays of different characteristics and compared to the indices calculated from a disturbance analyzer. Although the sample rate of the relays is smaller than that of the disturbance analyzer, the numeric relays can be used to assess the power quality of electric power systems.

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