Including yaw errors in DLC1.1

[SKMechatronicEngineering]

Hi,
According to IEC 61400-1, yaw errors shall be included when evaluating turbine loads.

The DLC generator in WEIS supports this, by allowing to define yaw errors using the yaw_misalign argument.

When I use WEIS to define yaw misalignment, the elasto-dyn input files are correctly generated to have an initial condition with an yaw error. Example:

-10 NacYaw - Initial or fixed nacelle-yaw angle (degrees)

However when the simulation is performed the yaw angle is ~0 deg in the entire simulation. Note that when performing DLCs the initial 120 s are not logged in the output file.

I think the reason for the yaw DOF to be repositioning at 0 deg, is because the ServoDyn input file is not correcly changed by WEIS, to set the neutral position equal to the yaw error.

0.0 YawNeut - Neutral yaw position--yaw spring force is zero at this yaw (degrees)
Is there a workaround that I can do to include yaw misalignment in the DLC simulation throughout the entire simulation?

[dzalkind]

Thanks for the notice, Søren. You are correct.

We have YawDOF disabled in the test case, which means YawNeut is not necessary.

This fix should work. We'll merge it into main when we get the tests to pass.

FYI, to see initial transients for deubgging, I do something like this:

    DLCs:
        - DLC: "1.1"
          wind_speed: [12]
          analysis_time: 1.
          transient_time: 0.
          yaw_misalign: [-10., 10.]