When designing the transmission grid, reinforcing the resilience of the grid's infrastructure against extreme weather events or exceptional situations that can cause cascading tower collapses is a fundamental criterion to ensure asset integrity. Overhead lines themselves are structured by incorporating reinforced anchor towers distributed along the route, which also play a key role as anti-cascade towers.
These elements, which possess greater structural robustness than conventional suspension or tension towers, act as containment points within the line: in the event of one or more towers failing, they can withstand the additional stresses transmitted by the conductors and prevent the failure from spreading down the line, acting as a 'firewall' that limits the propagation of the collapse.
Given the limitations of conventional simulation tools – which rely on traditional static approaches and cannot accurately assess the behaviour of these towers under multiple collapse scenarios – we at Elewit, in collaboration with Red Eléctrica, have spearheaded a project aimed at improving this analytical capacity, alongside Red Eléctrica's Lines Department and the company Akselos.
This initiative, based on advanced finite element simulation, has allowed us to use the software developed by Akselos to model complex mechanical phenomena efficiently, both in terms of calculation time and computational resources. On this basis, a specific model has been developed for the behaviour of anti-cascade towers when one or more adjacent towers fall, evaluating their structural response in extreme stress scenarios.
The analysis has successfully validated that the current design criteria for anti-cascade towers in the transmission grid are adequate to effectively contain the propagation of cascading failures. This validation provides an additional guarantee regarding the robustness of the existing design, aiming to ensure high system availability and integrity at all times, thereby minimising the extent of any incidents.
As a result, this project has reinforced confidence in current design standards and demonstrated the value of incorporating advanced simulation tools for the evaluation of critical infrastructure. Furthermore, this approach opens the door to future optimisations in the structural design of the transmission grid, based on a more precise analysis of the dynamic behaviour of the assets.