Session: 08-01-01 Risers, Pipelines & VIV

Paper Number: 100890

100890 - Vortex-Induced Vibrations of a Dynamic Power Cable for Floating Wind Turbines 

Dynamic power cables are important structural components of floating renewable energy converters, such as floating wind turbines and other marine energy converters. These flexible and dynamic cables are used for power transmission from offshore energy converters to the onshore system grid. With floating wind turbines set to become more prominent, it is important to understand any potential hydrodynamic interactions these cables are subject to. Although subsea power cables can fail by axial tension, bending, torsion, lateral compression, impact, abrasion, vibration, and sheath degradation, fatigue failures due to vibrations, caused by dynamic forces from ocean environments over a large range of waves and currents, are possible.  

Numerous studies have been conducted investigating the vortex-induced vibrations (VIV) of deep-sea risers and umbilicals but as of yet few studies have analysed these interactions in the context of dynamic power cables. VIV can lead to a significantly shorter fatigue life if they are of significant amplitude and frequency. This study investigates the VIV of a dynamic power cable for a semi-submersible floating wind turbine based on the NREL offshore 5-MW baseline wind turbine. This study is conducted within OrcaFlex utilising the Milan Wake Oscillator, Iwan and Blevins Wake Oscillator and Shear7 to observe the VIV behaviour under differing current conditions. The environment replicates that of the Equinor Hywind (Scotland) site with the cable in a lazy wave configuration. The response of the cable is investigated under varying sea current profiles. The results indicate that the behaviour of the vibrations is strongly dependent on the position along the cable with large variations in magnitude observed. The full paper will present the first study into these vibrations along the entire length of a dynamic power cable. The offshore renewable industry will benefit from the results reported in this paper. 

Presenting Author: Peter Elrick University of Edinburgh

Presenting Author Biography: PhD candidate at the University of Edinburgh investigating the vortex-induced vibrations of dynamic subsea power cables for floating offshore wind turbines in varying sea states. MSc in Sustainable Energy Systems attained from the University of Edinburgh and a BSc in Physics and Computer Science from the University of Durham.

Authors:

Peter Elrick University of Edinburgh
Vengatesan Venugopal University of Edinburgh