Simulation in Simulink below rated wind speed

Wind & Water Controls
1

Hello everyone,

I ran the simulation in Simulink using ROSCO.mdl with the following conditions.

  • Using IEA-15MW turbine
  • Using OpenFAST v3.5.3
  • Simulation time: 1500 sec
  • Wind speed: 8 m/s constant
  • Wave condition: still water

Since the water is still and the wind conditions are constant, it was expected that the turbine characteristics would be stable and that the blade pitch control would not be performed because the wind speed was below the rated speed. However, the simulation results were different from the prediction, as shown in the figure below.

sixsixfreedegree1
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So I have two questions.

  • Why was torque control implemented?
  • What modifications would prevent this control from taking place?

As an aside, when the simulation was performed using libdiscon.dll on a command prompt with only ServoDyn settings (PCMode, VSContrl, and YCMode) changed and no other changes made, the simulation results was stable at about 800 seconds after the start.

Thanks in advance,

Yuki

2

Hi Yuki,

The Simulink ROSCO controller is not maintained or actively supported because it can’t be automatically tested. We’ve left it online as a learning tool. I suggest you use the dynamic library version of ROSCO.

Torque control should be active below rated. You can read more about ROSCO here: WES - A reference open-source controller for fixed and floating offshore wind turbines

I think the wind speed estimator may be malfunctioning in the Simulink controller.

Best, Dan

3

Hi Dan,

Rather than asking “Why was torque control performed?”, it would have been more appropriate to ask “Why is the torque fluctuating even though it should be stable with steady wind?”

As you guessed, when I looked at the scope, it seemed that the values ​​output by the wind speed estimator were outliers, which caused fluctuations in the torque, generator speed, and blade pitch.

My professor told me, “Let’s use the Simulink model because it can be visualized and the code is written automatically,” but after reviewing your reply with him, we have decided to use libdiscon.dll from now on.

Thank you for your kind explanation.

Best, Yuki

4

Hi Yuki,

I’m new to learning dynamics in Simulink, and I’d like to quickly test it with a 15MW model. Could you please share your Simulink packages with the IEA-15MW turbine? I’d be very grateful for your help.

Thank you so much!
Yong

5

Hi Yong,

I don’t have these simulation packages, but you could build them using the inputs here: IEA-15-240-RWT/OpenFAST at master · IEAWindTask37/IEA-15-240-RWT · GitHub

Best, Dan