Blade-tower clearance-based aerodynamic imbalance analysis and fault diagnosis of wind turbines

Due to the development trend towards large-scale wind turbines with ultra-long blades, the risk of blade-tower collision has increased significantly, making collision prevention a critical engineering task. As blade-tower clearance is the most crucial indicator for evaluating the collision risk, it is necessary to study the clearance variation laws, particularly under conditions where clearance may drop below the safety threshold. Among these conditions, aerodynamic imbalance is the most common and nonnegligible one. Since clearance directly reflects the motion states of blades, it offers potential for diagnosing aerodynamic imbalances. In this study, a coupled analysis model of a 5 MW onshore wind turbine with aerodynamic imbalances was developed. The clearance time series under one normal operational condition and four typical aerodynamic imbalance conditions were obtained through numerical simulations. The effects of these aerodynamic imbalance conditions on clearance were analyzed statistically. Afterwards, a fault diagnosis model based on the MultiRocket algorithm was proposed. The performance and robustness of the proposed model were validated through comparisons with other commonly used algorithms. This study deepens insights into clearance variation laws and provides a precise fault diagnosis model for wind turbine aerodynamic imbalances.