An integral approach to ensuring the integrity of the tower and conductors

Ensuring the transmission of electricity by transmission overhead lines on safe way depends on ensuring the structural integrity of the towers and conductors. The towers of the an older power lines are manufactured at different time periods and are exposed to different mechanical stresses on the same overhead transmission line, due to different degradation of the materials and thus a different lifetime of the towers. However, the towers and transmission line are exposed hush climate and weather conditions which can lead to incidents or collapse of towers or conductor damages. The tower can be exposed to ice and wind loads, corrosion in legs. Today, many institutes and commercial companies are dealing with monitoring of transmission line conductors and towers. Recently, especial effort was made to development of anti-icing coatings of conductor and measurement of ice on conductors. The purpose of the paper is to present a novel method for monitoring of condition assessment and analysis of the results of continuous measurements of deformations in the legs of the towers and the temperature of the conductor with an expert system, which makes it possible to determine the different degree of the tower degradation. Not only tower degradation, but also in some cases the towers can be tilted or even pull out of base fundaments. Within the framework of the project task, a test system is installed on the 110 kV OHL Idrija – Cerkno, ELES, in Slovenia at the critical point of mountain peak The results of continuous monitoring are pre-processed on the autonomous system, which is on the tower itself and sent via the GSM network to the control centre. The results of the measurements are saved in the database for further expertise which quantifies the conditions on the transmission line under different weather conditions as well as the power transmission regime. Measured results are statistically analysed during last 30 seconds of measurements and presented in graphical and numerical form for expert system analysis. On the basis of such an integral approach and analysis of the results of continuous measurements it is possible to determine the influence of individual parameters (influence of climatic conditions and current loads) on the behaviour of the conductor (bends, tensile forces) as well as the tower (change of own frequencies, state of profiles, ...) with the aim of interpolating these impacts over a long period of time to the estimation the actual lifetime of the tower construction and to ensure safety of operation regarding to the external clearances of the overhead line.