EMEC wraps integrated subsea cable monitoring system try-outs

Illustration/EMEC cable section (Photo: Orkney Photographic/EMEC)

An Innovate UK-funded project focused on developing a smart integrated monitoring system for offshore energy subsea cables has drawn to a close after the trials at the European Marine Energy Centre (EMEC) in Orkney.

The novel technology will ultimately lead to better maintenance and repair of underwater cables, reducing costs in the offshore energy sector, according to EMEC.

Illustration/EMEC cable section (Photo: Orkney Photographic/EMEC)

The 12-month project, dubbed CLEMATIS, demonstrated the technical and commercial viability of a new multifunctional distributed sensor system for the monitoring of subsea cable infrastructure in the offshore renewable energy sector.

The project included the Fraunhofer Centre for Applied Photonics and Synaptec, whose technologies were integrated into the system, and EMEC and SEA, who provided market intelligence, test equipment and facilities to enable the system to be tested in real life conditions.

The CLEMATIS system is a holistic monitoring system that exploits the optical communications fibre in marine power cables. The system turns entire lengths of power cable into reconfigurable acoustic and temperature sensors.

A quasi-distributed electrical system makes use of the same optical fibre to interrogate passive electrical current and voltage sensors distributed throughout the infrastructure.

The power grid (Image: Fraunhofer)

This is the first time that such techniques have been combined into one monitoring system enabling end users to simultaneously monitor temperature and load on the energy network, and log any cable trauma such as anchor strike, scour related cable strumming or mistakes in cable installation, EMEC said.

Potential faults can be captured before turning catastrophic, and major faults or outages can be located immediately with accuracy, the Orkney-based center claims. Therefore, the system is expected to bring about a step change in offshore renewable energy operations and maintenance, reducing the requirement for visual inspections thus cutting ROV, diver and vessel hire costs.

Henry Bookey, leader of the CLEMATIS project from Fraunhofer UK Research, said: “Fibre communications are widely used in cables and umbilicals in oil and gas applications. The ability to monitor real time cable status can save huge sums in lost production through early indication of fault development and help avert major problems by diagnosing and pinpointing cable damage in real time.

“The technology emerging from the CLEMATIS project will allow cable health to be monitored accurately and cost effectively. As the project draws to a close, we are seeking opportunities and potential partners to take this solution to market.”

Short for Cable Lifetime Enhancement via Monitoring using Advanced Thermal and electrical Infrastructure Sensing, the CLEMATIS system was found to have potential to detect much more than tidal flow or direct cable disturbance. Early results indicate the system may even be able to pick up external acoustic signals, for example from passing vessels and even interaction with marine mammals, according to the studies.

The project built on the 2016 desk-based ORCHIDS feasibility study which identified various breakthrough techniques that could be combined into a single power cable monitoring system and provide detailed fault prediction, dynamic thermal rating implementation and fault location.

CLEMATIS progressed this initial study from the desk to laboratory and early field tests both on and offshore. In June 2018, the system was demonstrated on a live subsea cable at EMEC’s Fall of Warness tidal energy test site, according to EMEC.