Reliability and risk-based planning of operation and maintenance of offshore wind turbines

Reduction of the levelized cost of energy for wind turbines are very important in order to make wind energy competitive compared to other energy sources, especially for offshore wind turbines. Therefore the turbine components should be designed to have sufficient reliability but also not be too costly (and safe), and it is important to include in the reliability assessment the information obtained during operation (from condition monitoring and inspections) and the maintenance performed (incl. repairs and replacements). The paper presents a risk-based approach for optimal planning of Operation & Maintenance of offshore wind turbines. Further, the paper considers models for uncertainty modelling and reliability assessment of structural components such as tower, blades, substructure and foundation as well as cast steel drivetrain components. The function of a wind turbine is highly dependent on many electrical and mechanical components as well as a control system also reliability aspects of these components are discussed in the paper. Illustrative examples are presented considering uncertainty modelling, reliability assessment and risk-based planning of Operation & Maintenance.