Wind turbine steady-state response

Wind & Water Computer-Aided Engineering Software Tools
1

Dear Jason,

Below is Figure 9-1 found in the report “Definition of a 5-MW Reference Wind Turbine for Offshore System Development”. I would like to generate a similar steady-state response plot for a wind turbine that I’m currently modeling in OpenFAST.

steady_state.png
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It was described in the report: “We obtained the steady-state response of the land-based 5-MW baseline wind turbine by running a series of FAST with AeroDyn simulations at a number of given, steady, and uniform wind speeds. The simulations lengths were long enough to ensure that all transient behavior had died out; we then recorded the steady-state output values. … Start-up transient behavior is an artifact of computational analysis. To mitigate this behavior, we suggest using the steady-state values of the rotor speed and blade-pitch angles found in Figure 9-1 as initial conditions in simulations.”

Could you elaborate on how the steady-state values are obtained? After periodic steady state has been established, is it appropriate to use the time average of the time series in the last rotor revolution?

Thank you in advance,
Jing

2

Dear Jing,

Yes, that is correct.

That said, we are currently working with Envision Energy to add new steady state solver within OpenFAST so that steady state solutions can be solved directly, rather than by running time-domain simulations and waiting for all start-up transients to die out. This new functionality should be publicly released later this fall.

Best regards,

3

Dear Jason,

I just intend to follow up. Have you made the solver mentioned above available within OpenFAST? Can I now get the steady-state responses directly with the current OpenFAST version of 3.5.2 if I want to recreate Fig. 9-1 by myself? Thank you!

Kind regards,
Puyi

4

Dear @Puyi.Yang,

Unfortunately, that project was put on hold for some time, but development of a direct steady-state solve is continuing, a bit slowly. So, “no,” such functionality does not exist in OpenFAST v3.5.2.

Nevertheless, you can generate Figure 9-1 from the NREL 5-MW baseline wind turbine specifications report without such functionality.

Best regards,