Comparison of transfer path characteristics for different wind turbine drivetrain variations

To reduce acoustic emissions of a wind turbine (WT), the source of the vibrations (e.g. blades, gearbox), the emitting surfaces (e.g. blades, tower, nacelle cover) and the transmission between the source and surface have to be studied. The focus of this paper lies on a method to identify relevant transfer paths between the WT drivetrain and the sound-emitting surfaces and their respective contribution. The identified transfer paths can be used to improve turbine acoustics, especially by identifying problematic transmission areas.This paper will cover the application of transfer path analysis methods for different wind turbine drivetrains. The method will be applied to an MBS model of a 3 MW turbine. Different Bearing arrangements of the drivetrain and their influence on the Transfer path are compared. With the result of the TPA, developers will be able to determine critical contributions to the tonal behavior of the turbine and optimize either the transfer characteristics or the excitation specifically responsible for tonal behavior. The methods described can be applied to field measurement as well as an MBS-Model of the turbine to be able to optimize transfer characteristics during development.