# WindPact 1.5MW pitch range

Dear all,

Is WindPact1.5MW (WP1.5MW) with the default data given in CertTest folder that comes with FAST designed for “Pitch to feather” or “Pitch to stall”?
What is the typical range of Pitch motion for Pitch to feather 1.5MW turbine?

I have generated power curve (surface) using AerodynV15.04, from the Fig01 I realized that (Pitch_opt:2.5 deg, TSR_opt:7.4296, Cp_max:0.4804) as the peak point on the Power Surface.
Density = 1.225 Kg/m^3; Rotor radius = 34.73m; Swept area: 3.79E+03 m^2;
I calculated rated wind speed from 0.5*(1.2253.79E03V_rat^3)*0.4804=150000 and it turned out to be V_rat=11.04 m/s.
From this rated wind speed and TSR =0.4804, I obtained rotor speed as 2.3615 rad/s (22.55 RPM);
Control law for for region3 i.e (V>11.04 m/s) is:

• Keep the rotor speed constant at the rated value of 22.55RPM and vary “pitch angle alone” as the wind speed increases.
Now, suppose the wind speed is 18m/s (uniform and steady), blades and tower are assumed rigid. In order to keep the power constant at the 1.5MW, the desired Cp is 0.111 (=1.5E06/(1.2253.79E0318^3); As I decided to keep the rotor speed constant , Tip speed ratio (there may be transitions byt eventually) would be: 4.556 (= 34.73*2.3615/18). So all that is left now is to find the pitch angle corresponding to this TSR of 4.556 such that Cp=0.111. But when I look at the plot of Cp vs pitch, I realize that there is NO pitch angle which meets this objective in the range [-4deg 10deg]. I may get there by increasing the range of pitch angle, but I am wondering is it really going to require that high deviation in pitch? or some thing wrong with my understanding.

Edit: In the Fig:02 the legend reads TSR reads as 0.35 but it should be 4.556. Graph corresponds to TSR=4.556. Mistake in legend name only.

Regards,
Kumara

Dear Kumara,

I generally agree with your calculations, but I haven’t confirmed that all of your numbers are correct. I certainly notice some small differences to what is reported for the WindPACT 1.5-MW baseline turbine, e.g, as discussed on our forum here: http://forums.nrel.gov/t/cp-power-coefficient-of-windpact-1-5-mw-turbine/790/2.