Hello,
I am a recent user of FAST, and I am trying to simulate a wind turbine for my final project. I am stuck with the pitch control. I want to use Craig Hansen´s PitchCntrl_ACH control, but I have some questions about it.
First of all, how can I introduce the pitch rate? I was not able to found it, neither in primary FAST file nor in pitch.ipt file.
Secondly, I do not know exactly how the CNST(1) works. Where is applied? How it influences the rest of the control?
And last but not least, I realized that the simulation runs properly in most of the load cases, but I have some problems running the simulations with an ECD wind profile. An unstable torque, and consequently, unstable power, appears when the simulation is supposed to be stable. I strongly believe that it is due to a malfunction of the pitch control. I have plotted the results, and the pitch response is not the desired. I am trying to change the integral and proportional gains, but I see several differences between the way these gains are calculated in Craig Hansen´s routine and the way they are calculated in NREL 5MW reference. A function called GS appears in the first one, while GK appears in the second one. I can obtain the GK function for my wind turbine. Could you recommend me an adaptation of this function, in order to obtain the coefficients required by pitch.ipt file?
Thank you for your attention and I apologize if the questions are too simple for a forum like this and for my bad English too.
Best regards.
Dear Manuel,
Craig Hansen’s pitch controller, PitchCntrl_ACH.f90, is more of an example than an officially supported NREL-supplied routine. It is difficult to support questions on PitchCntrl_ACH.f90 now that Craig Hansen has retired. The only documentation of PitchCntrl_ACH.f90 that I’m aware of is in Appendix E of the WindPACT Rotor Design Study Report: nrel.gov/docs/fy06osti/32495.pdf.
Its sounds like you have some knowledge of the NREL 5-MW baseline turbine controller, which was developed and is supported by NREL. Instead of using PitchCntrl_ACH.f90, could you adopt the NREL 5-MW baseline turbine controller for your needs?
Best regards,
Dear Jason,
Thank you for the help, I will try to adapt the control. I hope it will be useful.
Best regards,
Manuel Caño
Hello again,
While I was reading the NREL 5-MW pdf document, I saw appendix A, and the variable “PitManRat(i)” (pitch rate (in absolute value) at which override pitch maneuver for blade i heads toward final pitch) appears. I tried to introduce it in my own primary input file, but I was not able to do it. Several error messages appears when I did it.
Where can I introduce that value in my simulation? Would you recommend me a different way instead of NREL 5-MW?
Thank you for your support and sorry again for my bad English.
Regards
Dear Manuel,
The NREL 5-MW turbine controller is implemented as a Bladed-style DLL. All of the controller logic and constants/parameters are self contained within this DLL. You shouldn’t add parameters to the FAST primary file. Instead, change the constants/parameters at the top of the DLL source code to suite your needs and recompile the DLL.
Best regards,
Hello,
The version of FAST provided by NREL website has not got the DLL controller implemented. I only have the opportunity to use that version (I can´t compile anything due to lack of knowledge and compiler), and I would like to know if the pitch rate is taken into account in this version of FAST.
After studying the Appendix E, I am able to understand that routine, but I can´t find anything related to the pitch rate, so I suppose FAST make something (that I do not know) in order to obtain that value.
So, where can I find something related to pitch rate on the “normal” version of FAST?
Thank you in advance for your support. I am sorry if I made some linguistic mistakes.
Best regards,
Manuel Caño
Dear Manuel,
In FAST, the pitch rate (and associated limits, if applicable) is determined by the pitch controller, not by FAST. The baseline controller (Bladed DLL) for the NREL 5-MW turbine includes an 8 deg/s pitch-rate limit. The baseline controller for the WindPACT 1.5-MW turbine does not include a pitch-rate limit.
The Bladed DLL control interface is one of the standard options of FAST v8: wind.nrel.gov/public/jjonkman/FA … erface.exe.
Best regards,
Dear Jason,
Thank you very much for your help. I think I will be able to solve my problems with that info.
Best regards,
Manuel Caño
Hi, my query is regarding pitch rate (hence I am posting it here).
I’ve read that the max pitch rate for 5 MW turbine is 8 degrees/sec. I’m working on a 1.5MW turbine model and I want to choose a value that is close to reality. What would the value be? (considering contemporary wind turbine control systems) Would 5-6 degrees/sec be a reasonable assumption?
Also, I’ve read elsewhere (not in our forum) that there could be different limits for pitch increments and decrements. It was mentioned that the limit for pitch increments was 4 degrees/sec and for decrements, it was a mere 0.7 degrees/sec. Is there such a vast difference in both usually?
Regards,
Sarat