EMEC: Cable strumming poses the greatest risk for subsea cables
EMEC and the Crown Estate have issued a report on the performance of subsea cabling in high energy environments to support the development of commercial wave and tidal energy sites.
Sub-sea Cable Lifecycle Study aims to improve industry’s understanding of the best ways for managing subsea cables for wave and tidal energy projects by researching the performance of the installed cables at EMEC test site in Orkney.
The first cables were installed over 10 years ago, and since, EMEC has collected considerable amount of data.
The study states that the subsea cables installed at the EMEC test sites appear to be in general good condition, with some serving wear within a few areas of significant strumming risk.
Each of the cables was reviewed in terms of installation methods, faults, operational life and electrical and ROV surveys.
By comparing data from risk analysis calculations, usually carried out prior to installation, and actual damage to the cables, it was possible to understand the accuracy of predictive calculations.
The report concludes that in sites with high tidal flow the greatest risk to subsea cables is the effect of cable strumming – vibration caused by the flow of water past the cable.
The study offers recommendations to developers of wave and tidal energy project including: carrying out calculations to assess the risk of strumming at an early stage, completing detailed site surveys and optimizing the cable route to avoid key risks, and protecting the cables with armouring in high energy environments.