Offshore wind array cable and cable protection system (CPS) integrity management using ROV3D
Overview
Offshore wind farms use array cables to connect wind turbines to each other and to offshore substations.
The segment of array cable from turbine egress to seabed burial is strengthened using a cable protection system (CPS) to mitigate dynamic forces that contribute to cyclical fatigue which, over time, leads to cable failure.
Nevertheless, risk of CPS failure remains high, resulting in large repair costs and lost production.
Array cables and cable protection systems require routine inspection to check for any damage or signs of excessive movement.
Solution
ROV3D real-time 3D imaging was used to map the route of the CPS from the seabed to the monopile. The inspection was performed by ROV in fewer than 30 minutes per cable, simultaneously with general visual inspection operations.
Measurement options included point to point distances (from turbine egress to seabed touchdown, seabed touchdown to seabed burial), angles (cable exit angle and bend radius) as well as the cable catenary shape (lazy loop confirmation) and cable marine growth accumulation.
The live pass 3D models gave the user assurance that quality data was being captured as well as acting as a coverage mapper to visually confirm areas that had been inspected. ROV3D allows our customers to objectively compare changes in the profile of the cable protection system over time to identify integrity concerns.
Benefits and value
ROV3D is a non-invasive method of inspection, requiring no contact with the structure of interest and no cleaning prior to inspection
Data capture is performed during visual inspection operations, there is almost no additional time involved with using ROV3D versus GVI alone
This equipment does not need to be operated by specialist personnel. Remote training is provided in 2-3 hours at the time of mobilisation, and customers can access remote onshore assistance
The stereo-synchronized video recorded on the ROV3D system can be archived and used to generate 3D models at any time in the future
Real-time results allow for in-situ decision making
Additional processing and reporting are available to further enhance results, analyze, and to prepare customer specific reports