Sensitivity of Drivetrain Condition Monitoring Signals to Wind Turbine Blade Damage

This paper studies the sensitivity of drivetrain condition monitoring system (CMS) signals to blade damage, exploring how these signals, particularly vibration, can serve as a potential tool for detection and tracking damage progression. This is achieved using a decoupled simulation approach, combining an aeroelastic solver with a drivetrain model. First, aeroelastic simulations are performed in OpenFAST, where the low-speed shaft (LSS) forces, moments, and tower top position vector are extracted and transferred to the drivetrain model. The drivetrain is modelled using the multi-body simulation environment SIMPACK. Blade damage is introduced in OpenFAST by reducing stiffness in the flap-wise or edgewise direction. The reference DTU-10MW onshore wind turbine is used as a test case. First, the impact of blade damage on LSS shear forces is analysed. Then the drivetrain response is assessed using virtual velocity sensors placed at the main bearing, rear bearing and gearbox housing. Results indicate that damage occurring in the blade mid-span region shows higher sensitivity compared to tip and root locations. A positive correlation is observed between LSS shear force and bearings side-side velocity, with higher forces leading to increased vibration. Additionally, the trend suggests that higher stiffness reduction results in higher velocity, indicating damage progression.