Risk-based Inspection Planning Optimisation of Offshore Wind Turbines

Wind industry is substantially propelled and the future scenarios designate offshore locations as important sites for energy production. With this development, offshore wind farms represent a feasible option to accomplish the needed energy, bringing with it technical and economical challenges. Inspection and maintenance (I&M) costs for offshore sites are much larger than for onshore ones, making the choice of suitable I&M planning for minimising costs important. Risk-based inspection planning (RBI) for offshore installations represents a suitable methodology to identify the optimal maintenance and inspection strategies to ‘control’ the deterioration in facilities such as offshore wind turbines (OWT), where fatigue and corrosion are typically affecting these structures. This article considers an RBI approach applied to OWT based on the developed methodologies for oil and gas installations, but considering the lower reliability level for wind turbines. This framework is addressing fatigue prone details in welded steel joints typically located in the wind turbine substructure. The increase of turbulence in-wind farms (IWF) due to wake effects is taken into account using a code-based turbulence model. As part of the results, life cycle reliabilities and inspection times are calculated for IWF location and single/alone location of OWT. The results indicate earlier inspection times for IWF.