Numerical Modeling of the Micromechanics Damage of an Offshore Electrical High-Voltage Phase

Abstract

Due to the strong growth of offshore renewable energies, research and engineering in this field is constantly expanding. One of the centerpieces of these technologies is the high-voltage electrical cable, generally made of copper, to transport the energy produced from the offshore farm to the onshore station. The critical nature of these cables lies in the proven resistance that they must demonstrate during stays underwater for several years, even decades, in difficult environmental conditions, which begin at the handling, shipping and underground burial stage. The marine environment can lead to deformation of the copper wires well beyond the limit of proportionality and, consequently, to breakage. Copper, although being an exceptional electrical conductor, has very poor mechanical properties. The plasticity generated by the excessive deformation of copper wires affects all of the physical properties of copper. When plasticity develops, electrical transport is affected and the heat within copper increases, but care should be given to not exceed 90 °C, as this would result in the shutdown of the cable with dramatic economic consequences. The work carried out in this article, which is part of the National Project EMODI as well as the European Project FLOW-CAM, aims at studying the mechanical behavior of the phase in order to correlate the deformation levels reached to the phase geometry as well as operating mechanisms of damage which reflect the proliferation of microstructural defects within the conductor. To do this, we propose a numerical model using Abaqus. Correct description of the effects of several parameters (geometry of the phase) and plasticity development on the performance of the phase were simulated and discussed.

Failure Analysis of a Suspended Inter-Array Power Cable between Two Spar-Type Floating Wind Turbines: Evaluating the Influence of Buoy Element Failure on the Cable

“…The minimum bending radius of the cable directly influences the severity of the deformation of the copper. Over-deformation of copper leads to a decrease in all physical properties of copper and even causes fracture due to the plasticity of copper [9]. The study by Matine and Drissi-Habti [10] investigated the effect of damage mechanisms on the behaviors of submarine power phase conductors.…”

Preliminary Multiphysics Modeling of Electric High-Voltage Cable of Offshore Wind-Farms

“…As the wires in general are made of copper, which is a very weak material, these stresses will gradually develop plasticity into wires, thus gradually leading to their failures. These plastic deformations are due to the formation, multiplication and displacement of mobile linear defects (dislocations) within the crystal lattices of the metal [2], which act as barriers to the transport of electrical charges. The movement of existing dislocations as well as the creation of new ones, therefore, changes the mechanical behavior of the metallic material, but also changes its physical properties (electrical, thermal, etc.).…”

“…The movement of existing dislocations as well as the creation of new ones, therefore, changes the mechanical behavior of the metallic material, but also changes its physical properties (electrical, thermal, etc.). A great deal of research has been devoted to the aging of high-voltage power cables, and several facets were studied; especially the aging of XPLE by water-trees, structural health monitoring by way of embedded fiber-optic sensors to assess plasticity of copper, and how mechanical loading beyond the elastic limit also defines the "elastic limit" for both electric and thermal behaviors [2][3][4][5][6][7][8][9].…”