Abstract
With the ageing infrastructure and fast-growing demand faced by utilities worldwide, voltage uprating is one of the most effective solutions and strategic approaches in asset management decisions. In this study, a systematic voltage uprating method is used to propose the new voltage level, based on the existing transmission lines’ physical structure, by utilising appropriate techniques. Prior to work conducted, the existing 132 kV transmission line was first examined in terms of the clearances and the components attached, and a technical issue on the clearance under still air was found to be a significant concern, particularly on phase-to-earth arrangements. Next, the proposed techniques and processes, by increasing the insulation strength and improving air conductor clearances, were used for the individual existing 132 kV transmission tower. The proposed voltage uprating of the 132 kV transmission tower comprehensively examines phase-to-earth under normal and extreme wind conditions based on electrical clearance requirements for 275 kV transmission lines. The proposed uprating model was then simulated using the Finite Element Method (FEM)-based commercial software under several lightning conditions, i.e., various basic lightning insulation levels (BIL) and different flashover mechanisms, taking into consideration still air and wind conditions for the voltage profile and its insulation strength analyses. The study found that the voltage profile condition for the proposed voltage uprating model was able to withstand its BIL under all conditions and thus satisfied the electrical requirement needed.
Highlights
All over the world, we are faced with a growing cumulative population, the development of large industries, and the evolution of the advanced transportation sector, which have been steadily contributing to the increasing demand for electricity
Another study reported that a major challenge for voltage uprating is to provide sufficient air clearance for the new level of voltage, this study found that by adjusting insulator length and its creepage distance had achieved sufficient electrical clearances of the new voltage lines’ needs [13]
In order to fulfill the requirement of electrical clearance, the 132 kV transmission line towers were modified by adjusting insulator lengths and their creepage distance
Summary
We are faced with a growing cumulative population, the development of large industries, and the evolution of the advanced transportation sector, which have been steadily contributing to the increasing demand for electricity. In previous work [14], multiple techniques have been used to uprate the existing 41.6 kV sub-transmission lines to 115 kV with minor modifications, such as re-insulation, reconductoring, midspan spacer, and a pole-top bracket for centre phase installations in order to resolve technical issues (i.e., electrical clearance requirement). In Japan, the existing 66 kV transmission line faced two main technical issues to uprate to 154 kV line that involved clearance around tower and insulation between conductors in span, and it was found that the proposed techniques of insulator supported jumper and phase-to-phase jumper succeeded to fulfill the electrical clearance requirements [16]. FEM simulations carried and power frequency to examine the withstand under were various conout on the proposed voltage uprating model by considering transient overvoltages ditions (i.e., still air and wind conditions) on the insulation strength. The simulations results were compared with the estimated critical flashover voltage (CFO) as the benchmark
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