Questions regarding the Kp gains of ROSCO in Region 2

Dear Jason, Bonnie, or Nikhar,

I am working on the ROSCO control tuning but I have a question regarding the Kp gain in Region 2. The paper (Nikhar et al 2019) mentions that the A is parameterized by wind velocity, but I only found a single Kp in the ROSCO controller for NREL5MW, DTU10MW, and IEC15MW. I read the ROSCO code and Simulink model and there is no scheduling process for Kp(v). Recently, I found there is an option in the ROSCO_toolbox (https://github.com/NREL/ROSCO_toolbox/blob/8ac261d15354dcbdfa645af75a74de29a23c55a6/ROSCO_toolbox/controller.py#L533), which scheduled the Kp based on the wind velocity vector below the rated wind speed and also has an option to specify a wind speed to interpolate the Kp gain at this point.

Does this mean the single Kp_vs in the ROSCO DISCON.IN is interpolated at a fixed wind speed? If so, what is this specific wind speed? If else, what is the condition? Thank you

Reference:
Abbas, N.J., A. Wright, and L. Pao. An Update to the National Renewable Energy Laboratory Baseline Wind Turbine Controller. in Journal of Physics: Conference Series. 2020.

Hi Xianping,

This is admittedly not very clear - sorry about that!

The region two gain schedule is, technically, scheduled by v and calculated at each wind speed. In the ROSCO toolbox, this happens here:
github.com/NREL/ROSCO_toolbox/b … er.py#L252

When the DISCON.IN file is written, the last value in the vs_gain_schedule is used:
github.com/NREL/ROSCO_toolbox/b … es.py#L123

So, this corresponds to, basically, rated wind speed, as it is the wind speed coresponding to the last value in v_below_rated as defined here: github.com/NREL/ROSCO_toolbox/b … er.py#L161

I hope this clears things up for you.

Cheers,
Nikhar

Hi Nikhar,

Thank you for your reply. Yes, I also found this operation in writing DISCON.IN. Have a good evening!

Xianping