Extracting condition monitoring information from a wind turbine drive train

Condition monitoring of large wind turbines to improve their reliability in an offshore environment is an important component of providing reliable energy from renewable sources. The paper describes a test rig to demonstrate condition monitoring of the drive train of a small wind turbine, including turbine, main bearing, gearbox, double-fed induction generator (DFIG) and converter. The monitoring is done through the terminals of the electrical machine, but includes external signals such as torque, speed and vibration. The wind turbine operates at variable speed and defects in the drive train initiate a complex array of harmonic effects, which vary with turbine speed. Previous research in this area has involved monitoring vibration transducers on the turbine nacelle and drive train, seeking trends. This research takes a different approach, using an understanding of the machine dynamics and electrical machine theory to link the causes of faults to detectable effects on the rotor dynamics of the overall drive train.