WP5: This Work Package focuses on achieving SO4. It develops and validates a modelling framework which estimates the effect of environmental conditions and operating strategy on the reliability of main bearings and gearbox. . The choice of bearings as focus of the study is dictated by the significant downtime caused by frequent bearing failures10 combined with lengthy repair actions, leading to large expenses, further exacerbated offshore due to the difficulty of access. The demonstration and validation of this model should pave the way for a shift in O&M strategy, where the effect of loading on component degradation is taken into account and the operation is adjusted accordingly, to reduce the possibility for unscheduled failures, or increase performance in situations with low impact on reliability.
The reliability estimation is based on detailed component models, which use the load assessments produced in WP3 as inputs, and estimate the material deterioration using physics-based degradation laws. These models are used, together with measured wind turbine load data, to identify reasons for component health degradation under specific turbine operating conditions. A validation of the damage progression rate predictions against bearing lab test data is carried out. The calibrated model for estimating probability of failure vs. turbine operational years conditional on operating conditions serves as input to WP6.