minor error in ex12

[dhcho347]

This is not important but,

https://github.com/NREL/floris/blob/main/examples/12_optimize_yaw.py#L166

      yaw_opt = yaw_opt_full * (6.0 - wind_speed) / 2.0  # Linear ramp up

The above code should be changed like below for ramp up, I think

      yaw_opt = yaw_opt_full * ( wind_speed - 4.0 ) / 2.0  # Linear ramp up

or

      yaw_opt = yaw_opt_full * ( wind_speed - 3.0 ) / 3.0  # Linear ramp up

[rafmudaf]

I'm not sure of the intended result here, but just adding some more info. In the current code for wind speed of 4 m/s, that would be:

yaw_opt_full * (6.0 - 4.0) / 2.0 = yaw_opt_full * (2.0 / 2.0) = yaw_opt_full

However, in the first proposed change, it would be yaw_opt_full = 0.0.
In the second, it would be:

yaw_opt_full * (4.0 - 3.0) / 3.0 = yaw_opt_full * (1.0 / 3.0) = yaw_opt_full / 3

[dhcho347]

https://github.com/NREL/floris/blob/main/examples/12_optimize_yaw.py#L163-L170

        if (wind_speed < 4.0) | (wind_speed > 14.0):
            yaw_opt = np.zeros(nturbs)  # do nothing for very low/high speeds
        elif wind_speed < 6.0:
            yaw_opt = yaw_opt_full * (6.0 - wind_speed) / 2.0  # Linear ramp up
        elif wind_speed > 12.0:
            yaw_opt = yaw_opt_full * (14.0 - wind_speed) / 2.0  # Linear ramp down
        else:
            yaw_opt = yaw_opt_full  # Apply full offsets between 6.0 and 12.0 m/s

□ Above code change the yaw offset on (4, 5) and (13,14) m/s

as your calculation,

• • 4m/s : (6-4)/2 = 1.0 * yaw_opt_full
  • 5m/s : (6-5)/2 = 0.5 * yaw_opt_full .. (1.0 > 0.5 : Down) (?)
• • 13m/s: (14-13)/2 = 0.5 * yaw_opt_full
  • 14m/s : (14-14)/2 = 0.0 * yaw_opt_full .. (0.5 > 0 : Down)

□ Both are down as below figure.

□ I though your intention was (Up and Down) as below

[rafmudaf]

Excellent results @dhcho347! Your third option looks correct to me. @bayc is the original author and will have a better idea of the intended control settings.

[Bartdoekemeijer]

Good catch! It should be the third option!

[Bartdoekemeijer]

Actually, a more elaborate answer is the following. The yaw angles should be clipped rather than scaled to stay within the bounds. Thus, the maximum yaw angle may be 20 deg at 12 m/s, 10 deg at 13 m/s and then 0 deg at 14 m/s. If the optimizer found an optimal yaw angle of 8 deg at 13 m/s, then this value should not be scaled or clipped: it's still within the bounds. In the current example 12, the angle is scaled (unnecessarily).

FLASC contains a code that takes care of ramp-up and ramp-down clipping. See https://github.com/NREL/flasc/blob/e425509e551c521e895c34e29db17f97ddf6f174/flasc/wake_steering/lookup_table_tools.py#L18. For more professionalized use cases, I would recommend using this function.