Hi Pietro,
Thanks again for your help with this. Yeah, I’ve working on some scripts myself on that front, it is certainly a challenging area! Some initial results appear positive but needs more time.
Out of curiosity, I’ve noticed a consistent problem I’ve had when producing Campbell diagrams via the MATLAB Toolbox scripts where at certain rotational speeds, the frequency will change rapidly (the first graph I posted in this topic is one such example).
I’ve not figured out what is the immediate cause of this and decided to try the baseline onshore 5MW model that is used in the example with the aim of replicating the results in this linearization paper (https://www.researchgate.net/publication/308755735_FAST_modularization_framework_for_wind_turbine_simulation_full-system_linearization).
Again, the results line up well with the example up until around 10rpm where I see a sudden drop in 2nd Tower FA and 2nd Blade Flap Frequencies.
In terms of setup for this I largely followed the process from the linked paper, albeit here I just used Elastodyn with blade and tower DOFs enabled (no generator, yaw or drivetrain DOFs enabled).
For operating points I ran it from 0 - 14rpm in steps of 2 with 0 pitch angle.
In terms of linearisation options, steady state was found each time (NLinTimes = 36, TrimTol= 0.0001).
Worth noting as well that here I used openfast v2.4 but in that first graph I used v3.3.
I don’t see anything that is immediately wrong with my setup, do you have any suggestions with what could be the cause here? I feel like I am maybe missing something obvious. To me it is odd that I am having similar issues across different RWT models and openfast versions.