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Error while running simulations using python
Hi,
I’m using a python script based on sample.py to do some simulations. The following sea state ran without problems.
H=5.47m;Tp=9.89s;Uwind=23.6m/s.
Output:
Time: 0.00 Windspeed: 15.625 Torque: 0.0000e+00 u_x: 0.00187 Pitch: 0.00 loads0: 142150.13
Time: 0.05 Windspeed: 15.641 Torque: 0.0000e+00 u_x: 0.00190 Pitch: 0.00 loads0: 153534.27
Time: 0.10 Windspeed: 15.653 Torque: 0.0000e+00 u_x: 0.00192 Pitch: 0.00 loads0: 151038.73
The following sea state however gives an error:
H=0.80m;Tp=6.19s;Uwind=14.3m/s.
Output:
Solver setup failed
LU factorization reported a problem, zero diagonal for instance
Solver setup failed
LU factorization reported a problem, zero diagonal for instance
Solver setup failed
LU factorization reported a problem, zero diagonal for instance
Solver setup failed
LU factorization reported a problem, zero diagonal for instance
Solver setup failed
LU factorization reported a problem, zero diagonal for instance
Solver setup failed
LU factorization reported a problem, zero diagonal for instance
Solver setup failed
LU factorization reported a problem, zero diagonal for instance
Solver setup failed
LU factorization reported a problem, zero diagonal for instance
Solver setup failed
LU factorization reported a problem, zero diagonal for instance
Time: 0.00 Windspeed: 15.625 Torque: nan u_x: nan Pitch: nan loads0: nan
QSimulation: “Rotor Geometry Could Not Be Recontructed! NaN values found in rotor Geometry.”
NAN VALUES PRESENT IN GEOMETRY – simulation should be aborted!!!!
NAN VALUES DETECTED IN WAKE CALCULATIONS – simulation should be aborted!!!!
Traceback (most recent call last):
File “d:\Documenten\QBlade\QBladeCE_2.0.5.2\simulations\test.py”, line 30, in <module>
QBLIB.advanceTurbineSimulation()
OSError: exception: access violation reading 0x000001D770C9F370
Broken filename passed to function
Broken filename passed to function
Do you know why this happens?
Hi Hannes,
I dont think that this issue is related to the seastate. It seems like for some reason the structural model is not converging and this could be caused by many different things. What you can do is to save the project with the storeProject() function and have a look at it in the GUI version of QBlade. If you cant identify the issue you can also share the .qpr file here and we can have a look at it.
BR,
David
Hi,
Thanks for the quick response! This is the error I get when I run the simulation in the interface.
‘Rotor Geometry Could Not Be Recontructed! NaN values found in rotor Geometry.’
I have attached the .qpr files with a simulation that runs (simul29) and one that doesn’t(simul5). I don’t see why the one runs and the other not since the loads are heavier in the simulation that does run.
Hannes
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Hello,
indeed this is an issue with the wave field, altough not really intuitive and quite specific to the scenario you simulated.
The 0.4m amplitude wavefield contains some high frequency wave components (>1Hz) with “large” wavenumbers. During the evaluation of the depth distribution (for finite depth waves) of the wave velolcities these high frequency components (with very low amplitude ~ 1mm, and no real “influence” on the structure) caused floating point issues which led to NaN values appearing in the forces.
I have fixed this issue now for the upcoming release, until then what you can do is to regenerate the wave fields and set the cut-out frequency (disabling automatic frequency range in the “Frequency Discretization” section) to a number below 1 Hz, try 0.5Hz. This removes the high frequency wave components and resolves the issue.
Another thing I saw in your project files is that you have a very low torsional stiffness in your substructure, causing the turbine to yaw wildly. But maybe thats intentional?
BR,
David
Hi David,
Thanks,this solved my problem and there was a mistake in my calculation of the torsional stiffness, so thanks for noticing that!
Hannes
