| dc.description.abstract | This thesis was written in collaboration with Glitre Nett, where the purpose is to analyse the lifespan of power masts in the high voltage distribution grid in Agder. This is done by studying several factors that can impact the lifespan of the masts and by developing a model to estimate the number of masts that should be replaced in the coming years, based on how the grid is operated today.
Access to electricity is essential in today's society. However, it is difficult to determine an exact lifespan for the power lines in the grid. Therefore, several factors such as impregnation, foundation and the number of poles were considered as possible influencing factors on the lifespan of the power lines, in addition to age. It was found that a pole impregnated with salt is less prone to failure than a pole with creosote. Within the category of foundation, it was found that a pole standing in soil is better than a pole standing on bedrock. Finally, it was analysed wether a mast having one or two poles would impact its lifespan. The analysis indicates that a mast consisting of two poles will fail before a mast consisting of one pole.
Two Weibull distributions were fitted for the Kaplan-Meier estimate to describe it as a survival function S(t) and a hazard function h(t). Both functions were represented using a left and right side, where t^* is the distinction between right and left side.
The number of masts that need to be replaced in 2023 was simulated using both Monte Carlo simulation and a normal distribution. The outcomes of these two methods were nearly identical. The model's ability to reproduce data was also analysed by comparing simulated results with historical mast replacements from 2013 to 2022.
Finally, a model was developed to simulate the number of future mast replacements over time, using a Monte Carlo simulation of a Markov chain.
Power lines are the type of power distribution system that causes the most errors, which leads to high costs related to non-delivered energy in the high-voltage distribution grid. This study contributes to an increased understanding of the factors that affect the lifetime of power masts and could possibly be used a tool that to plan future maintenance of the power grid in an efficient way. | |