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Linearization of OC4-Semi in OpenFast3.0 #812
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Dear @blueblueyaro, Your approach sounds fine. Here are my answers to your questions:
I hope that helps. Best regards, |
Dear jjonkman, Thanks for your detailed reply. Your answer helps me and now I have some new questions.
Thanks again. BR, |
Dear @blueblueyaro, Here are my answers to your questions. I would also suggest that you review the corresponding posts on our forum, where the linearization process has been discussed many times: https://wind.nrel.gov/forum/wind/.
Best regards, |
Dear @blueblueyaro, Regarding (2), when you enable the platform DOFs, are you also enabling HydroDyn and MAP++? Otherwise, the platform DOFs will not be restrained and a steady-state solution will not be found. When VSContrl = 1, what is happening to the time series of rotor speed, etc. before this error is obtained? When you set VSContrl = 0, you must select a generator model; which one have you selected and have you set realistic values for its parameters? Regarding (3), can you clarify how you running OpenFAST (supposedly through the Simulink interface in MATLAB?) and when this error occurs? I see that you've enabled HydroDyn, but not MAP++, so again, the platform DOFs will not be restrained and a steady-state solution will not be found. Best regards, |
Dear @blueblueyaro, The setting of The "nodal output" warnings will not effect the simulation results; you can ignore these warning. Regarding the setting of Can you clarify what you change between a simulation that runs to completion and a simulation where MATLAB crashes? I'm not fully understanding what you are doing. Best regards, |
Dear @blueblueyaro, Just to confirm--you are saying that OpenFAST within MATLAB crashes when Regarding your direct questions:
Best regards. |
Dear jjonkman, Your answer helps me a lot. Thank you very much! I attach the relevant input files below for you. I think it may caused by RdtnMod=0 while ExctnMod=2 with CompHydroDyn enabled. Further, I found these states in .lin file, what are they for? And can I exclude them when I rearrange state space model for GenDOF and PtfmPDOF with single input collective blade-pitch? BR, |
Dear @blueblueyaro, OK; thanks for the files. I haven't had a chance to look at them yet, but thanks for clarifying that the problem is likely caused by the mixture of Regarding the HydroDyn states (HD RdtnPtfmP#), these are first-order hydrodynamic states that capture the wave-radiation "memory effect", generated by setting Best regards, |
Dear @blueblueyaro, I ran your model and confirm that OpenFAST v3.0 crashes with an access violation error when the OC4-DeepCwind semi model is linearized with Regarding your model, the only potential issue I saw in my brief review is that you've specified Best regards, |
The way the code is currently structured assumes that |
Dear all,
I am trying to obtain a linearized state space model of OC4-Semi WT in OpenFast 3.0 for LQI controller design. I want to verify the steps and there are also some questions. As initial attempt, I want to get a SISO model (blade pitch as input and generator speed as output) for collective pitch control for power regulation.
I followed the steps in 5.6.2. Linearized models for one simulation (manually) in the document and also refferred to Linearization of the model #738 and then I got .lin files 1 to 36 (OP: wind 18m/s, Torque 43093Nm, blade pitch 0.26rad). The DOFs I chose were FlapDOF1, DrTrDOF and GenDOF. ComHydro and ComMooring were swithed off.
I used GetMats_f8.m in matlab-toolbox-main and 1.lin to 36.lin for postprocessing, then I got AvgAMat, AvgBMat, AvgCMat, AvgDMat, etc. as the result.
Questions:
Is there any step I did by mistake? Thanks for your answer very much.
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