Increasing the ampacity of underground cable lines by optimising the thermal environment and design parameters for cable crossings

Abstract

The problem of optimising the thermal environment and design parameters of underground cable lines for cable crossings with the aim of increasing the ampacities of cables is considered in this paper. Particle swarm optimisation (PSO) algorithm, formulated as a continuous non‐linear optimisation problem with constraints, for solving this hot spot problem is applied. It is found, using the PSO algorithm, that there are a suitable size of cable bedding and an arrangement of cables within that bedding, which can eliminate or significantly mitigate the hot spot effect without the use of any additional cooling equipment. In this manner, the ampacities of both crossing cable lines increase by about 15% on average with respect to the case of a similar crossing with installation parameters commonly used. In addition, it is shown how the cross‐sectional areas of the conductors and metal screens and the metal screen bonding methods affect the optimal solution.

Analysis of Increased Induced Voltages on the Sheath of Double-Circuit Underground Transmission Lines Guaranteeing Ampacity

“…Consequently, installing and using power cables along a route requires overcoming underground obstructions at different depths and considering intersections with important, busy avenues [2,3]. In such scenarios, the underground transmission line must either circumvent or pass through these obstacles, which can include a diverse range of elements such as gas pipelines, water pipelines, medium-and low-voltage cables, and, in some cases, ground that is challenging to excavate, such as in areas with fragmented rock, which increases the excavation costs and time for the activity [3]. In these sections of the line, it is recommended to use duct banks that require shallower installation depths, such as flat duct banks.…”

“…However, accurate knowledge of cable ampacity is required to avoid overheating the cables. However, many utilities ignore the setting of the ampacities of cables that are crossed by these underground obstructions [3], while some other utilities apply a derating of up to 5% [2]. Furthermore, because of the restructuring of the electricity industry and the introduction of the electricity market worldwide, transmission lines are becoming more and more loaded and, in most instances, operating with the maximum possible currents, that is, ampacities [3].…”

“…Few publications in the literature deal with cable crossings and the changes in the duct bank along the route. In [3,[8][9][10], the authors only evaluate the ampacity problem when the cables pass through underground obstructions and do not evaluate the induced voltages on the sheath along the cable route.…”

Optimization of Ampacity in High-Voltage Underground Cables with Thermal Backfill Using Dynamic PSO and Adaptive Strategies

“…Research has also explored the impact of controlled backfill quantity on native soil thermal resistivity [13,19] and the ampacity of high-voltage cables in relation to cable spacing, burial depth, and backfill size [20][21][22]. Recent studies, such as those by [23,24], have employed algorithms like PSO, Jaya, MJaya, and NSGA-III for multi-objective optimization, ranging from backfill cost minimization to improving the thermal environment in underground lines. In [25], the calculation and analysis method of cable ampacity in a ductbank is studied using the NSGA-III algorithm for multi-objective optimization, while [26] uses the grey wolf optimization algorithm to enhance ampacity, achieving an optimal design of high-voltage cable layout in tunnels.…”