Alfredson R., Davis L., Joshi A.

Noise from Wind Turbines and comparisons with Standards. R J Alfredson, L Davis, A Joshi Monash University, Australia Currently Australia is developing Standards to predict noise levels from Wind Turbines which are based largely on various Standards developed mainly in European countries. There is some uncertainty about whether potentially different environmental and topological conditions could affect the predicted noise levels in residential areas in Australia. Extensive measurements have been carried out in Victoria of a newly established wind farm located in a country area. These covered a range of distances from the wind farm, a range of wind speeds, wind directions and atmospheric conditions. Acoustic measurements were simultaneously collected and included the overall noise levels, the A weighted noise levels, spectral details, as well as statistical parameters such as the LA10, LA90 and LAeq. Class I, II and III methods of noise prediction were investigated. Detailed examination of the results indicated that the existing methods were generally adequate to give a reasonable prediction of noise levels in most cases. A wide scatter of results was obtained particularly at very low wind speeds. A large number of trends were observed as well which related to variations in noise levels with time of day, wind speed, and wind direction. It was established that the calculations of the non-directional sound power levels were generally below the manufacturer’s guaranteed values. The directional characteristics were not as well contained although the variations were considered to be acceptable. The spectral data produce mixed results. The background noise level LA90 did not contain any discernable tones. However some tones were present (and were discernable when listening) in the graphs of LA10 and LAeq in the kilohertz region. The present indications are that the proposed Standards are appropriate for Australian conditions.