CABLE PROTECTION
FEATURE SPONSOR
ENSURING ADEQUATE PROTECTION FOR OFFSHORE CABLES
Cable failure is regarded as one of the principal operation and maintenance issues for operational offshore windfarms.
While the importance of ensuring the stability of wind turbine foundations through the laboratory-testing of new and existing designs is becoming well- recognised, the stability of cables for in-field transmission and power export is often a secondary consideration. However, providing adequate
protection for offshore cables, whether through sufficient burial or physical protection is complicated further by other considerations such as the thermal properties of the soil and the impact on cable overheating.
PHYSICAL PROTECTION
If physical protection is required, ensuring its performance is able to meet the various bed level changes that may be encountered over a cable’s lifetime requires a risk-based approach that considers the environmental drivers that will impact on the stability (e.g. soil properties, general bathymetric change, local scour, hydrodynamic forcing and cable integrity). Whilst it is preferable to develop designs that meet the stability requirements for the installed cables at the construction phase, where cabling stability issues have arisen subsequently, for example at offshore substations after a period of operation, it is important to provide an effective solution which can be retrofitted to solve the specific scour problems, and to provide remediation measures that future-proof against further erosion.
FAST FLOW FACILITY
HR Wallingford is internationally recognised as an authority on seabed processes, with an active programme of research in the prediction and analysis of scour around marine structures, with world class modelling facilities, including the Fast Flow Facility. This, together
with advanced computational fluid dynamics models, provides a controlled environment in which to evaluate and select the best-performing scour protection systems for a specific site and the conditions in which it operates.
PROVEN EXPERTISE
HR Wallingford has proven expertise in developing solutions to mitigate scour problems for foundations and cables. This includes working out the best way to deal with cables at substations, wind turbine foundations, other subsea infrastructure and in engineering studies which help to avoid scour problems around cabling before they arise.
As an example of some of the issues experienced at offshore wind turbine foundations, local scour at the foundation
structures can lead to the exposure of previously buried cables, increasing the risk of cable fatigue through hydrodynamic loading and possible vortex-induced vibrations (VIV), and ultimate failure. Although the immediate risk to the cable may be relatively low, the longer term risk with respect to cable integrity can be high, particularly if the exposed cable span becomes large.
SCOUR PROTECTION PLACEMENT
Even in cases where cables have been protected through the placement of scour protection, large-scale seabed changes and local scouring can lead to the undermining and collapse of the protection measures and in the case of mattresses, can result in ‘washing lining’, adding significantly to the risk of cable failure.
26
www.windenergynetwork.co.uk
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68
