Red Eléctrica currently 1,200 kilometers of submarine cables on service that enable the transport of electricity under the sea or ocean in places such as the Balearic or the Canary Islands. Thus, in 2012 the company started up the first direct current submarine interconnection in Spain, a route between the Peninsula and the Balearic Islands. However, the maintenance of submarine cables and their potential repairs are very complex mainly because of their difficult access.
To analyze its condition, periodic topographic inspections of the sea surface are programmed using probes, known as bathymetries, which make it possible to assess the severity and possible effects on the health of the asset. The high technical complexity is due to the fact that in order to know the condition of the cable, engineers have to perform mechanical stress calculations (among others) based on a large number of variables in a dynamic environment over an element of tens of kilometers, which requires a lot of time and which, moreover, are not always feasible.
With the aim of developing a solution that facilitates the work of technicians and engineers, Elewit, through its fourth Venture Client program, launched a project with Akselos, a company that has one of the most advanced engineering simulation software in the world. Elewit's venture client program is focused on testing, validating and, if necessary, introducing technological innovation projects in the activities of the different companies that make up Redeia, while at the same time promoting the development of technologies and efficiencies within the group.
In this regard, Elewit selected Akselos because the algorithm patented by this Swiss startup allows Red Eléctrica to monitor, based on predefined conditions, the entire life cycle of the assets.
The project’s objective was to develop a software tool, adapting the Akselos algorithm to Red Eléctrica's submarine cable study scenarios, thus generating a mechanical model of the cable that could take information from the bathymetries. In this way, Red Eléctrica would not depend solely on the indications and limited information provided by the manufacturer of these assets, since the tools developed with Akselos allow expanding this information independently to the benefit of the best practices for the management of the asset.
Two possible application cases were analyzed during the project.
- Evaluation of the free spans effect on cables
A free span is a point along the cable suspended between two elevated points due to seabed movement. Cables must be located directly above the seabed, so a free span causes potentially damaging stresses on the cables.
The software allows modeling the effect on the cable of both free span and other elements such as sea currents. In this way, a fatigue analysis can be performed to know the state of health of a given section of the cable. - Perform simulations prior to maneuvers
These simulations take into account, among other variables, the sea conditions, the type of ship and tooling to be used and are necessary to ensure that the integrity of the cable is not affected during the laying maneuvers. It is important to know its condition, because if it is not optimal, the cable could be damaged even before it is operational.
The results of the project proved that the software developed offers sufficient guarantees to apply the Akselos technology to these two real case studies for which recent information from the manufacturer is available. As a consequence, the next steps will be to perform with this tool: a detailed analysis of a free span detected in the Mallorca-Ibiza cable and eventually, an analysis focused on the free spans of the future submarine link between Tenerife and La Gomera will be performed, analyzing the results of the test with the information provided by the cable manufacturer. The results will also be compared with those of other software or the combination of several, since, at this moment, no other software that integrates the full functionality of Akselos is known.