Copel's experience on uprating a 69 kV Compact Overhead Urban Transmission Line into 138 kV (Supercompact urban transmission line)

摘要

Copel is a Brazilian electric utility and the largest company in State of Parana, southern Brazil. Copel has been developing compact arrangements for 69 and 138 kV urban transmission lines since late 1970's in order to erect these transmission lines in both densely populated areas and cities with lack of physical space. The erection of lattice transmission lines towers would not be allowed in such places due to the towers dimensions. The compact transmission lines were design to minimize the ambient and visual impact observed during the construction of underground transmission lines, as well. This technical article is going to present the Copel's experience on development of arrangements for 69 and 138 kV compact urban transmission line so far. It will be presented the main characteristics of the urban transmission lines for 69 and 138 kV developed by Copel and which are constructed in the main cities in Parana State since early 1980's. The use of compact arrangements instead of underground transmission lines allowed Copel to expand rapidly its 69 and 138 kV grid with reduced impact. Due to the increasing demand in the 69 kV grid, some studies for 138 kV grid uprate took place in order to use the same infrastructure and phase to phase distance. Thus, the first Copel's 138 kV urban transmission line arrangement with very reduced phase to phase distance was created and it was called supercompact urban transmission line. This article will present the Copel's experience on the developing the supercompact transmission line and its performance so far. This new arrangement can be used to both compact urban transmission line uprating from 69 kV into 138 kV and to new urban transmission lines that need reduced phase-to-phase distance. This article will show all stages of the development of the new arrangement and also it will be presented the experience on the very first urban transmission line erected with this new arrangement in Brazil so far. It also presents the preliminary researches, corona effect and withstanding tests, surge impedance calculation for overvoltage studies on EMTP ATP software, design criteria and erection of an urban transmission line nearby Curitiba, Brazil in which the new arrangement was applied. This transmission line performance is satisfactory so far. The electric and magnetic field emission were analyzed in order to meet the Brazilian and ICNIRP's exposure limits. Copel has extensive experience on urban transmission line arrangement developing and it was surely increased by the using of the new arrangement proposed in this article.