Impact of wind turbine operation conditions on infrasonic and low frequency sound induced by on-shore wind turbines

In this paper, the influence of wind turbine operation conditions, like rotational speed, nacelle position and output power, on the low- and infrasonic sound emissions at the wind farm and sound immissions at residential buildings will be investigated. For this purpose, parallel measurements were carried out at a wind farm on the Swabian Alb in complex terrain and at four residential locations in the vicinity of the wind farm over a period of two months. Distinctive tones can be assigned to the blade passage at different rotational speeds. Furthermore, tones at 28.9 Hz (rated) and 18.3 Hz (below rated) with two higher harmonics can be attributed to the wind turbine generator. Wind farm infrasonic tones at the blade passing frequency were detected at the wind farm and residential buildings. At the residential buildings infrasonic tones were detected mainly for maximum rotational speed of the wind turbines and seem to be independent from wind direction.