Análise de desempenho frente a impulsos atmosféricos induzidos em circuitos de média tensão

Abstract

Isolation coordination has been focused on several studies in the latest years. Recently the continuous change on electrical power market associated to the costs related to penalties due to interruptions on power availability, as well as maintenance on the distribution system has been a great motivation to studies aiming to review the application of arresters on medium voltage systems. Within this background, this study develops and applies a new method for analysis and improvement of performance of overhead power distribution lines related to induced over voltages caused by lightning. The developed procedures were applied to 19 power feeders under AES ELETROPAULO responsibility. Aiming to review lightning isolation coordination methods, in a concise way, especially in respect to induced over voltages caused by lightning, the State of Art comprises: surge protection for medium voltage AC circuits, technology of the arresters applied to these circuits emphasizing the main characteristics and operation differences, as well as the main rules on arresters application. The main steps on the routine development regarding the induced over voltage calculation on the LIOV-EFEI program are discussed and presented. A methodology is developed, proposed and applied aiming to adapt the complex real geometry of the circuits to a system suitable to be studied by the LIOV-EFEI program. Studies contemplating the “induced over voltage calculation – Insulation coordination” are developed and the detailed results for one of the feeders are developed and analyzed. The insulation coordination studies require the dielectric strength of the circuit equipments. The dielectric strength of sample equipments from AES-ELETROPAULO was tested on the High Voltage Laboratory of the Federal University of Itajubá - LAT-EFEI - as suggested by national and international regulations. However those results are not focus of discussion or presentation on this work. Therefore the dielectric strength data applied on this work are considered real. Finally conclusions and suggestions are presented for future developments on this area.