Thomas Gellermann, expert for machinery diagnostics at the Allianz Center for Technology (AZT), recently gave a talk at a conference on vibration in wind energy converters. With 175 attendees, the conference of the Association of German Engineers (VDI) was very well received. Among the attendees were wind farm operators, turbine suppliers, producers of components and other wind energy specialists.
His presentation focused on the behaviour of drive trains in wind energy converters. The analysis he presented was based on metrological investigations of different geared turbine units over the past few years. Results of a comprehensive analysis on a 5 MW prototype performed by contract of BARD Emden Energy were also included.
The rotor blades of such a wind turbine cover an area as large as almost two soccer fields (more than 10,000 square meters).
One might assume that the winds and thus the pressure on the different blades are all the same but this is far from the truth. In fact, wind is very local phenomenon, and thus the wind speed varies greatly in an area. The different transverse forces are applied and transferred from the blade via the rotor bearing to the gearbox.
Depending on how the drive train is constructed, different loads affect the gears. Thomas Gellermann showed that a three-point rotor bearing arrangement causes larger bending moments on the input gear shaft. A separate rotor bearing arrangement can carry the different tilting moments from the irregularities in the wind field. However, it is also essential to include an elastic element in order to provide the flexibility that is needed to compensate deformation effects of the base frame at high transversal loads.
Watch video of the presentation at VDI (German language only)
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