I am researching the effect of modeling the blades using Beamdyn and Elastodyn on structural loads simulations .
The included measurement are flapwise bending moment besides fore-aft tower bending moment and rotor speed.
for that I have used an Independent blade pitch controller based on linear quadratic gaussian with LQR and Kalman filter and the baseline gain-scheduled PI controller.
Could everyone who sees the post share their comments and interpretations that can be concluded from those results?
Thank you very much in advance.
I’m not exactly sure what you want comments on, but just a few initial comments:
- I would expect some differences in the turbine response when modeling the blades with ElastoDyn and BeamDyn, given the higher-fidelity beam model in BeamDyn, including blade torsion.
- I’m a bit surprised by the seemingly large change in tower damping between ElastoDyn and BeamDyn.
- The units of the flapwise bending moment output from BeamDyn are not correct; they should say Nm, not kNm.
Dear Professor Jonkman,
Thank you for your swift response. I am hoping to get comments for each WT measurement individually to describe:
1- the response deviation between both solvers
2- most importantly the cause in each solver leading to this deviation.
My interpretation for the 3 measurements is that ElastoDyn does not model torsion and since the IPC and CPC controllers operate in region 3, where a relatively high torsional load is expected, this leads to the controllers pitching the blade differently based on each blade model.
For rotor speed response:
my only remark is that BeamDyn modelling resulted in faster response.
For blade flapwise bending moment:
BeamDyn modeling resulted in higher load measurement compared to response with ElastoDyn.
Finally for the tower bending moment response:
I am also surprised with the significant response in damping and my only interpretation for the reason behind it is that the tower receives excitation from rotor blades as a whole, so for 1P revolution of structural loading on the blades leads to 3P frequency response on the tower.
Could you please share your thoughts/ comments about the 3 measurements.
Thank you in advance.
Note: the model of wind turbine is the NREL 5 MW RWT and all control and operation parameters are set identically when modeling with both solvers.
I agree with your commentary. My guess is that it is the blade torsion, which is accounted for in BeamDyn but not in ElastoDyn, is the main reason the two results differ.
I think that the differences of tower and blade bending-moment response in BeamDyn and ElastoDyn relate to the aerodynamic damping. For the tower, aerodynamic damping gives the largest contribution. And, our research (Redirecting) show that the pitch angle of blade influence the aerodynamic damping of tower.