Instalação de capacitores de potência em redes poluídas por harmônicos e com baixa potência de curto-circuito

• Ano de defesa: 2011
• Autor(a) principal: Roberta Dantas Ribeiro
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Baixa potência de curto-circuito; Ressonância; Distorção harmônica; Capacitores PPM; Engenharia elétrica
• Link de acesso: http://hdl.handle.net/1843/BUOS-994FCY

The power factor correction by means of capacitors and the proliferation of nonlinear loads in the electrical system strongly increases the probability of equipment overload due to excessive harmonic distortion. This work presents a case study in which the inclusion of non-linear loads, undesirable resonance frequencies and the plant low power short-circuit have as consequence the failure of metallized polypropylene (PPM) capacitors connected to two different bus bars in the electric system of a small mining plant. From the analysis of the device characteristics and electric measurements on the bus bars, the premature PPM capacitors failures are identified. To mitigate this problem, solutions are analyzed and the installation of a tuned filter in the bar with the highest harmonic current injection is the alternative that offers the best cost benefit ratio. Aiming to prevent the filter components failure, technologies and characteristics of the capacitor and reactor are discussed and specified. Finally, the influence of the shortcircuit and X/R ratio of the supply network impedance on the harmonic distortion andimpedance variation of the bus bars are discussed. The aim of this work is to be a reference for electrical system designers who deals with power factor correction with capacitors installation in harmonic polluted and low power short-circuit plants.