Effect of individual blade pitch angle misalignment on the remaining useful life of wind turbines

Abstract

An empirical data set of laser-optical pitch angle misalignment measurements on wind turbines was analyzed, and showed that 38 % of the turbines have been operating outside the accepted aerodynamic imbalance range. This imbalance results from deviations between the working pitch angle and the design angle set point. Several studies have focused on the consequences of this imbalance for the annual energy production (AEP) loss and mention a possible decrease in fatigue budget, i.e., remaining useful life (RUL). This research, however, quantifies the effect of the individual blade pitch angle misalignment and the resulting aerodynamic imbalance on the RUL of a wind turbine. To this end, several imbalance scenarios were derived from the empirical data representing various individual pitch misalignment configurations of the three blades. As the use case, a commercial 1.5 MW turbine was investigated, which provided a good representation of the sites and the turbine types in the empirical data set. Aeroelastic load simulations were conducted to determine the RUL of the turbine components. It was found that the RUL decreased in most scenarios, while the non-rotating wind turbine components were affected most by an aerodynamic imbalance.