This work considers the characteristics and drivers of the loads experienced by wind turbine main bearings. Simplified load response models of two different hub and main-bearing configurations are presented, representative of both inverting direct-drive and four-point-mounted geared drivetrains. The influences of deterministic wind field characteristics, such as wind speed, shear, yaw offset, and veer, on the bearing load patterns are then investigated for similarity scaled 5, 7.5, and 10 MW reference wind turbine models. Main-bearing load response in cases of deterministic gusts and extreme changes in wind direction are also considered for the 5 MW model. Perhaps surprisingly, veer is identified as an important driver of main-bearing load fluctuations. Upscaling results indicate that similar behaviour holds as turbines become larger, but with mean loads and load fluctuation levels increasing at least cubically with the turbine rotor radius. Strong links between turbine control and main-bearing load response are also observed.

This paper investigates the relationship between wind turbine main-bearing loads and the characteristics of the incident wind field in which the wind turbine is operating. For a 2-MW wind turbine model, fully aeroelastic multibody simulations are performed in 3D turbulent wind fields across the wind turbine's operational envelope. Hub loads are extracted and then injected into simplified drivetrain models of three types of main-bearing configuration. The main-bearing reaction loads and load ratios from the simplified model are presented and analysed. Results indicate that there is a strong link between wind field characteristics and the loading experienced by the main bearing(s), with the different bearing configurations displaying very different loading behaviours. Main-bearing failure rates determined from operational data for two drivetrain configurations are also presented.

This paper investigates the relationship between main bearing loads and the characteristics of the incident wind field in which a wind turbine is operating. For a 2MW wind turbine model, fully aeroelastic multibody simulations are performed in 3D turbulent wind fields across the wind turbines operational envelope. Hub loads are extracted and then injected into a simplified drivetrain model of a single main-bearing configuration whose parameters are determined using finite element software. The main bearing reaction loads and load ratios from the simplified model are presented and analysed. The results indicate that there is a strong link between wind field characteristics and the loading experienced by a single main-bearing, with more damaging load ratios seen to occur in low turbulence and high shear wind conditions.

This paper presents the practical implementation of the receptance method in active vibration control. One significant advantage of the receptance method in comparison with conventional methods such as state-space is that it does not require the knowledge or evaluation of the system matrices M, C, K which usually contain modelling errors. A test structure is considered for partial pole placement using four non-collocated actuators and sensors. The first four flexural modes including two bending modes and two torsional modes are controlled. The method, in general uses the measured transfer function between the input/output data including the dynamics of the actuators and sensors. The control force distribution is chosen so that it excites certain modes easily while the other modes remain unchanged. Sequential multi-input state feedback is also applied to assign all the modes simultaneously.