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2007
Conference Paper
Titel
Passive and active dynamic vibration absorbers for gear box noise reduction in wind turbines
Abstract
In wind turbines the drive train, especially the gear box, is a significant source of noise. Significant contributions come from the gear mesh and from resonances of the structure like the main frame or the torque arm. The structure-borne noise from these sources is transferred either to the rotor or to the tower and radiated to the environment. The contributions to the noise spectrum from these sources are single tones in the frequency range from about 100 Hz to about 600 Hz. Especially tones with high levels are annoying and must be reduced. Several measures are possible to reduce these tones. One cost-effective and rapidly applicable method is to use passive vibration absorbers. The vibration absorbers for reduction of structure-borne noise developed by ESM are tuneable to nearly every frequency and mass required by the system. For special applications vibration dampers tuneable in all three co-ordinates are available. Modern wind turbines are running with variable speed. Therefore passive vibration absorbers which work only in a small frequency range come to their limit. For these challenging applications an active system based on piezo stack actuators shall be developed. This Active Vibration Absorber (AVA) works with two commercial piezo stack actuators in phase opposition.