I am using OpenFAST with Cygwin and am trying to run 15MW WT with UMaine Semisubmersible floater simulation. I have kept everything constant in the files as given. Upon running the simulation with DISCON.dll, I get the following error message:
I read other posts mentioning the time step. So I changed it to 0.005s and I get a Tower Strike error message:
I received another suggestion in GitHub about deactivating ServoDyn and GenDOF. So keeping ServoDyn enabled, switching GenDOF to False and keeping timestep as 0.005s, I get error as:
Is there any other suggestion I should follow so as to run this case successfully?
I haven’t run the IEA Wind 15-MW RWT atop the UMaine semi model myself, so, I’m not sure I can answer your questions. Just a few comments:
- The first error you report references an “Unknown ErrID”, which is not very useful. So, I’m not sure what the actual problem is. The “Unknown ErrID” issue was recently discussed on the OpenFAST github issues page–see: github.com/OpenFAST/openfast/issues/532. Does using the branch mentioned in that issue solve the first problem, or at least provide a better error message?
- The IEA Wind 15-MW RWT atop the UMaine semi model by default includes a DISCON-based controller, so, I would not expect that you’d have to reduce the time step for this model to run. Have you made any other changes to the OpenFAST input files?
- Regarding the tower strike error you are receiving, what mean wind speed are you simulating and are the initial conditions of your model (rotor speed, blade pitch) set appropriately for the mean wind speed?
thank you for your response. I went through the post you mentioned before, and followed the suggestion of compiling and downloading the Dev branch. so I did that and now it seems to run perfectly. I ran the Monopile case for now.
I am yet to run the Semi-sub model with the new compiled version.
Preveiously, I did not make any changes to the input files. Just downloaded them and tried running the simulations. The mean speed at hub height is 7m/s and turbulent windfield.
Have you initialized the mean rotor speed appropriately for the 7-m/s mean hub-height wind speed (i.e., set to the expect mean value)?
The initial rotor speed in the new files (i.e after I downloaded and compiled OpenFAST again with the dev branch in Aug end) was set to 5.11 rpm
I looked at the initial rotor speed in the Monopile files which I got when I downloaded and compiled OpenFAST for the first time (Jul 2020), it was set to 7.5 rpm. The hub height steady wind speed was 10m/s.
Initial rotor rpm with 5.11 rpm works fine.
How do I set the correct initial rotor speed according to the hub height mean wind speed?
Also, I was preparing the DLC matrix for wind turbine simulation. I have consulted both IEC 61400-1 and 61400-3 and NREL publications like ‘Dynamics Modeling and Loads Analysis of an Offshore Floating Wind Turbine’, ‘Definition of IEA 15MW Offshore Ref. Wind turbine’, ‘Definition of UMaine VolturnUS-S Ref Platform’ but I am not able to understand the calculation of significant wave height (Hs) for DLC 1.6. It states, Hs=1.09Hs,50-yr. But a specific site is supposed to have a single value for Hs,50 , so how can I calculate Hs for wind speeds 3-24m/s for the DLC 1.6?
The initial rotor speed should be set to equal the expected mean value for a given hub-height wind speed. You can calculate this by running the model to steady state. The mean values are also published in Figure 3-1 of the IEA 15-MW RWT specifications report: nrel.gov/docs/fy20osti/75698.pdf.
DLC 1.6 from the offshore wind turbine design standard calls for the 50-year extreme significant wave height conditioned on mean hub-height wind speed. These may be lower than the unconditioned 50-year extreme significant wave height.
I ran the 15MW model and got the output file.In the output data I want to find what I need,but all abbreviations.
I can recognize some of the names because they are the same as those in V8，and I don’t recognize someelse.
Do you know the specific meaning of these abbreviations？
I gather you are referring to the various output parameter names set in the OutLists of each module. These are described in the respective module-level documentation. The full set of OutList parameters are also documented in the OutListParameters.xlsx spreadsheet provided with OpenFAST on github–see: github.com/OpenFAST/openfast/bl … eters.xlsx.
THX for your help!
Its useful for me!