Thank you very much for your reply
When linearizing the WT around an operating point and switching on the Genspeed on we found the matrix AvgMatC=926.3 which corresponds to the generator speed as output
I am wondering what is the unit of the Genspeed (rpm or rad/s)?
and also the unit of the state (which is I think the rotor)
SINCERELY YOURS
Dear Ali,
The GenSpeed output has the units of rpm. The speed of the generator degree of freedom (expressed as the rotation of the low-speed shaft on the generator side of the shaft has the units of rad/s.
Best regards,
Dear Jason,
I am confused about the value of the rotor inertia of the NREL-5MW turbine. In ElastyDyn and also in the 5MW NREL documentation, it is written that it is
But in the forum here, I found this reply saying that it is 38,759,228 kgm^2. Is the "Hub inertia about rotor axis " is different from the rotor inertia?
Besides, in the two-mass model of the wind turbine (rotor/generator), I am also considering the damping ratio of the rotor and the generator besides the damping and spring constants of the low and high-speed shafts, as you can see in the picture below.
Are they considered in the 5MW NREL wind turbine? If yes, where can I find their values, please?
Kindest regards
Younes
Dear Younes,
The rotor inertia is the sum of the hub inertia and the blade inertias about the rotor centerline. In ElastoDyn, the hub inertia is specified independently from the blade mass distribution.
The damping of the rotor and generator are inherently calculated within FAST / OpenFAST, but they are not specified directly as damping constants. The rotor damping comes for aerodynamic loads dependent on structural velocity and the generator damping comes from the torque controller (the damping is the slope of the torque-speed curve).
Best regards,
Dear Jason @Jason.Jonkman
When running the linearization of NREL 5MW wind turbine, I face two problems.
First. One error occured when running the simulation, and it shows like this:
An error occurred while running the simulation and the simulation was terminated
Caused by:
Error in ‘ywt_NREL5MW_ITIBarge_NearRated_ROSCO/FAST Nonlinear Wind Turbine1/S-Function’ while executing C MEX S-function ‘FAST_SFunc’, (mdlUpdate), at time 49.900000000000006.
FatalException
Could you please help me to solve this error?
Second. From the FAST User’s Guide, I see that the PCMode should set to be 0, which represents none pitch control. Can we consider those 0 control modes as open-loop control? If we want to calculate the linearization results for the closed-loop we construct in Simulink, how should we do?
Looking forward to your reply! Thanks in advance for your help!
Dear @Yinghan.Liu,
Regarding the error you are recieving, I’m not sure. The error seems to be generated after the OpenFAST has already been completed. Have the OpenFAST results already been generated before the simulation terminated abruptly?
I agree that linearizing without active control enabled is equivalent to open-loop control. The effect of open-loop blade-pitch angle perturbations will still be included (in the B and D) matrices when LinInputs is set to 1 when linearizing OpenFAST.
OpenFAST does not have the ability to linearize controllers implemented in Simulink and include such terms in the linearized state-space matrices output from OpenFAST. You’ll have to augment the linearized matrices output from OpenFAST yourself to include the linearized effect of a closed-loop controllers.
Best regards,
Dear Jason，
Thank you so much for your quick reply！
The linearization in OpenFAST does conplete before the simulation stop abruptly. And the linearization matrix is all null. It seems like the parameters setting is wrong. I will check this later.
Thanks again！
---- Replied Message ----
From | Jason Jonkman via NREL Forumnotifications@nrel.discoursemail.com |
- | - |
Date | 02/29/2024 21:48 |
To | camille0327camille0327@126.com |
Subject | [NREL Forum] [Wind & Water/Computer-Aided Engineering Software Tools] Learizing Baseline 5MW Wind Turbine with FAST |
| Jason.Jonkman
February 29 |
- | - |
Dear @Yinghan.Liu,
Regarding the error you are recieving, I’m not sure. The error seems to be generated after the OpenFAST has already been completed. Have the OpenFAST results already been generated before the simulation terminated abruptly?
I agree that linearizing without active control enabled is equivalent to open-loop control. The effect of open-loop blade-pitch angle perturbations will still be included (in the B and D) matrices when LinInputs is set to 1 when linearizing OpenFAST.
OpenFAST does not have the ability to linearize controllers implemented in Simulink and include such terms in the linearized state-space matrices output from OpenFAST. You’ll have to augment the linearized matrices output from OpenFAST yourself to include the linearized effect of a closed-loop controllers.
Best regards,
Dear @Jason.Jonkman
When doing linerization in Simulink, it seems like there is an unavoidable bug. I would not only get the wrong linearization matrix, but also meet the abrupt stop I mentioned before. However, for the same input files, I can do the linerization correctly by DOS.
Anyway, thank you so much for your help!
Dear @Yinghan.Liu,
Regarding the OpenFAST simulation in Simulink terminating abruptly, can you clarify which version of OpenFAST you are simulating? Do you have this issue with any OpenFAST model that is linearized through Simulink? Does upgrading to the newest version of OpenFAST (currently release v3.5.2) solve the issue?
If not, we should report this as an issue to be fixed via the issues page of the OpenFAST repository: Issues · OpenFAST/openfast · GitHub.
Best regards,
