Influence of Loaded Power Cable Cyclic Transversal Bending on Trend Evolution of Dielectric Loss and Partial Discharges

Zero-emission goals necessitate future global energy strategies to rely on renewable energy sources. As a result, significant investments are being directed toward large-scale offshore wind farms around the world. This has led to substantial advancements and growing demand for submarine cables for linking these offshore farms to the power grids (especially, a new class that refers to floating cables that are exposed to cyclic or fluctuating mechanical stresses). In this article, investigations on the influence of a loaded power cable's transversal bending on its performance indicators during cyclic transversal bending are presented. During the tests, phase-resolved partial discharge (PD), dielectric-loss, and cable temperature measurements were simultaneously performed. The original concept was a real-time synchronous correlation of the above markers recorded up to the cable's electrical breakdown during consecutive bending cycles. The loaded cable temperature evolution was analyzed in correlation with the performance indicators and the number of bending cycles. The article presents an original methodology for measuring and assessing trends, along with a quantitative framework for analyzing the degradation of dynamic cables. The individual stages of cable degradation, such as the cracking of the wires in both the cable core and the outer screen as well as insulation deterioration, were identified and correlated with the dielectric loss waveforms and PD patterns. The methodology and results may contribute to the testing and diagnostics of dynamic power cables that are exposed to frequent mechanical movements during normal operations, such as in industry, mining, and (particularly) subsea applications. This is especially relevant for future submarine dynamic cables, which will demand enhanced mechanical and electrical durability.