December 10, 2020
Feature article – Continuous monitoring of offshore wind power cables
Subsea power cables for offshore wind turbines are subject to multiple forces during their installation and operation. Sea conditions can cause excessive movement in cables, and if these are not recognised and managed effectively, they can result in damage and premature fatigue.
Effective cable monitoring is essential to avoid costly repairs, replacement, or even abandonment. Digital solutions that provide insight through continuous monitoring can address existing design validation and performance assurance challenges, presenting new opportunities for the integrity management of these vital assets.
Fitting fibre optic cables along a power line is an established method of integrity monitoring, providing visibility of vulnerable locations and areas of potential failure such as third-party intrusion, dropped object impact damage, electrical arcing and cable exposure. Where there is direct exposure of a cable to harsh dynamic sea conditions, either by design or unexpectedly, greater accuracy in monitoring is necessary.
CRP Subsea (formerly Trelleborg Offshore UK) offers a new approach to cable monitoring. Working closely with a major operator, the cost-effective Mimir Motion Clamp was developed. This digital monitoring technology integrates with protection products such as CRP Subsea NjordGuard cable protection system or Bend Stiffeners, or attached via a standalone clamp system, negating the need for specialist support.
This new monitoring system provides continuous sensing and recording of motion data, with easy remotely operated vehicle (ROV) deployment and retrieval, ensuring repeated reliable clamping for many years. Engineered to be a simple, independent, self-contained, cost-effective monitoring solution, it allows several motion clamps to be deployed along a cable.
On battery power alone, monitoring and recording is through a state-of-the-art multi-sensor array housed within a uniquely hot-swappable pod. The pods house and protect the motion sensing electronic equipment during operation, providing continuous logging of data with the possibility of simultaneous replacement of more than one pod during recovery.
Access to e-learning, product documentation and installation guides, through CRP Subsea new Mimir Digital Technician app, powered by Mimir Digital Intelligence, further simplifies the solution. The app also provides an easy way to configure and set-up the motion clamp on the back of the vessel, removing the need for costly additional onsite specialist technicians and support.