Offshore wind farms have come a long way since the first was installed off the coast of Denmark in 1991. The market grew nearly 30 % per year from 2010 to 2018. However, today’s market is still far from exploiting its full potential to generate 420 000 terawatt-hours (TWh) per year globally, more than 18 times the global demand for electricity today). One important challenge for operators lies under the sea – in the high-voltage subsea cables that transport the power back to shore. The EU-funded SENTRY project has developed sophisticated real-time remote monitoring technology to minimise downtime, maintenance and repair costs, and lost revenue.
‘De-risking’ a risky business
According to project manager Marc Glenn of EDS HV Group, “the undersea cables connecting the wind turbine to an offshore supply station and then to shore can now reach up to 100 km. They are buried in a hazardous environment with moving sands, ocean waves, a shifting seabed, and even vessel anchors or fishing nets.” At least 10 subsea cable failures are declared to insurers every year, with claims in 2015 alone accounting for 77 % of the total global cost of offshore wind farm losses that year. A variety of cable health monitoring tools exists, supplemented with infrequent and costly periodic inspection. However, the financial impact of faults remains a critical challenge for the industry, impacting the competitiveness of operators and the enthusiasm of investors.
Minimising investment, maximising results
Distributed acoustic sensing (DAS) converts a standard optical fibre into an array of acoustic sensors. SENTRY exploited it by taking advantage of the fibre-optic cables for communication and monitoring already integrated into the subsea power cables. With the support and collaboration of DAS technology expert Optasense and numerous trial partners providing assets for technology validation, the team has delivered CableSENTRY™. It turns these fibre-optic cables into thousands of cost-effective sensors able to detect multiple pre-fault or fault scenarios. CableSENTRY™ supports 24/7 real-time monitoring from the EDS Belfast control room. Glenn explains: “In the case of a fibre break, within minutes EDS can let the customer know the ID and the GPS coordinates of the wind farm high-voltage cable asset with an accuracy up to 10 m, minimising the troubleshooting required and maximising uptime, enhancing the industry’s reliability and sustainability.” The team has filed a patent for its innovative and promising development.
Boosting big data, expanding applications
Glenn explains: “We discovered no fewer than 33 potential data streams that could be used to analyse cable health.” The SENTRY team is now working closely with IBM on data aggregation while simultaneously paving the way to the use of artificial intelligence and machine learning with an eye on a comprehensive decision support tool. “Our services significantly reduce generation downtime. By enhancing the efficiency of the offshore renewables industry, we make a difference in combating climate change,” Glenn concludes. “It doesn’t matter how ferociously the wind blows – without the export cable that brings the power back to shore, it can’t be turned into clean green energy.” CableSENTRY™ is lifting the wind energy industry to new heights.
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