Electric energy is currently at the heart of ecological, strategic and economic issues. Repeated political declarations constantly extol the merits of a safe, clean and sustainable supply of energy, guiding the development of new alternative resources to those conventionally used for electricity generation.
Wind energy is among the fastest growing alternative resources. Part of its production is expected to be in marine areas. This production is organized within sites called offshore wind farms. However, one should keep in mind that, the investment and maintenance costs of offshore wind farms, is very high. A failure can lead to huge losses due to the cessation of production. Access and intervention in the marine environment for maintenance operations require the use of specific equipment (boats, helicopters), highly skilled workers, as well as favorable weather conditions. The combination of these factors results in a relatively long repair and service restitution time. This works against the economic profitability of the offshore wind energy resource.
Underwater power cables from off-shore wind farms are among the components whose maintenance is a major challenge. These cables constitute the electrical distribution and transmission network. This network collects and transports the energy produced by wind turbines all the way to the shoreline. During this route, submarine power cables are subjected to aggressive environments (mechanical and / or chemical constraints, etc.) that can deteriorate their state, reduce and / or cancel their performance. It is therefore important to be able to follow the evolution and detect signs of degradation (punctual and / or global). OTDR-based electrical cable diagnostic methods exist that allow the detection and localization of faults, but the analysis of the measured signals needs to be improved, particularly through the use of models. The link between the physical degradation of the cable and the values of the electrical parameters has, to our knowledge, never yet been realized. As a result, we are not able to know the actual condition of the cable in its natural evolution environment, let alone its residual life.
The work carried out in this thesis aims at studying the mechanical behavior in both quasi-static and cyclic fatigue loadings in order to correlate the deformation levels reached to the operating mechanisms of damage and which reflect the proliferation of microstructural defects within the components of the phase (Conductor and insulators). To do this, we propose a numerical modeling using Abaqus. Then, again using numerical modeling, this time using Comsol, we tried to show the impact of mechanical damage on the physical properties (electrical and thermal) of the phase, emphasizing the role of copper. Insulators are playing a key role as well. However, the contour of the thesis had to be well defined in accordance with the time allocated and it seemed to us that a lot of information can be got out of the study of the conductor.
Key words: Mechanical degradation, wired diagnosis, underwater power cables, offshore wind energy, numerical simulation, analytical simulation
Stakeholders or Phd/Writer name
- Fouad Ech Cheikh