Robust Stabilization of Dynamic Subsea Power Cables of Offshore Wind Turbines using Retrofitted Nonlinear Energy Sinks

Background

• Subsea cable failures account for 77% of the total global costs of offshore wind farm losses.

• Exposure to fluid induced forces due to marine currents, waves and platform motion may cause fatigue and abrasion failure.

• Hence reducing cable vibrations is critical to mitigating risks of cable failure and ensuring reliability and resiliency of offshore wind transmission.

Inspiration

• Overhead transmission lines are damped using Stockbridge dampers which are low-cost & easy to install and maintain.

• However, the broadband nature of subsea cable vibrations renders the direct use of Stockbridge dampers ineffective.

• Hence, efforts were made to develop a damper which could be easy install and maintain but also provided broadband vibration mitigation.

Innovation

• Nonlinear energy sink (NES) is a nonlinear system with cubic stiffness capable of broadband vibration absorption.

• Cubic stiffness will be achieved using a post-buckled structure as shown in the figure alongside.

• The amount of buckling will be adjusted using a coupler.

• The proposed solution is an easy, affordable solution which can be retrofitted to any existing subsea cable by a diver or a remotely operated vehicle without lifting the cable from the ocean.