PhD Project: Risk-based Operation and Maintenance of Offshore Wind Turbines.

Costs to operation and maintenance (O&M) of offshore wind turbines are large, typically more than 25% of the cost of energy. Recent experiences from offshore wind farms indicate even larger costs. The costs consist of planned maintenance and corrective maintenance due to failure of components such as gearboxes, generators, blades, corrosion, fatigue and scour around the foundation. One main contributor to the high offshore O&M uncertainty and costs is the dependence on weather windows.

In other engineering areas such as the offshore oil & gas industry and civil engineering bridges, rational approaches to planning of O&M have been developed. These approaches are based on risk and reliability based techniques where it is possible to plan rationally future actions based on available information at the time of decision and models for costs and uncertainties.

For offshore wind farms cost models are available which describes all costs related to different maintenance strategies, but these models are based on past experience and simulation using historic data, and are not developed to assist in daily decision making on planning of next maintenance actions given actual data/information.

Hypothesis: Using basic theories from statistical decision theory a reliability-based basis for cost-optimal planning of operation and maintenance for offshore wind turbines can be developed to assist in decision making on planning of O&M implying a substantial reduction of the total lifetime costs to O&M.