Resumo:
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.
