Advanced Wind Turbine Program Next Generation Turbine ... - NREL

4.3.2 Mechanical Loads Testing of the EMD Turbine
Mechanical loads testing was conducted on the EMD turbine between June 11, 2002 and September
17, 2002. A total of 77 hours of valid data were collected during normal operation of the
turbine. The objective of the loads testing was to determine the relationships between wind conditions
and loads on the POC turbine under all normal and emergency operating conditions.
Loads were found to be acceptable.
GE conducted an internal study of the comparison between the measured mechanical loads and
those predicted by the dynamic simulations. The results show that the dynamic simulations do
an acceptable job of predicting the blade flapwise fatigue and the shaft torsion and bending fatigue.
They also generally do a good job of predicting the mean shaft torque.
The figures also show that the simulations tend to slightly underpredict the blade edgewise fatigue
and tower bending fatigue. This discrepancy is due, in part, to discrepancies in the calculation
of the rotating axes in the dynamic simulations versus the measured data. In general, however,
the agreement between predicted and measured data seems quite reasonable and inspires
confidence in the use of the simulations.
4.3.3 Acoustic Noise Testing of the EMD Turbine
Turbine and background acoustic noise data were collected between May 2, 2002 and May 4,
2002. The A-weighted sound power level at 8 m/s wind speed was calculated using two methods
for determining wind speed. The first method uses wind speed as measured on a temporary 10m
meteorological tower upwind of the turbine. The second method derives the wind speed from
measurements of turbine power and a power curve obtained from power performance testing. In
the case of the present testing, the two methods yielded very similar results of, respectively,
103.0 dBA and 103.3 dBA sound power levels. Additional acoustic testing included wind speed
sensitivity, directivity, one-third octave spectra, and tonal analysis. Figure 43 shows a comparison
of the EMD noise levels to levels historically associated with wind turbines of various sizes.
It is significant to note that the EMD turbine exhibits noise emissions below the average for turbines
of similar size.
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