SIMPLE VARIABLE-SPEED TORQUE CONTROL for LINEARIZATION

Wind & Water Controls
1

Hi,
I am working on the linearization of a direct-drive wind turbine and would like to examine the modal behavior of the model through feature analysis. I am using ‘runLinTurbine.py’ and would like to try linearization for the power generation state at rated wind speed. I have a few questions:

Due to linearization, I had to use simple variable-speed torque control. Is this option correct?

Could you please explain the specific meanings of these four parameters, especially the fourth one?

             VS_RtGnSp   - Rated generator speed for simple variable-speed generator control (HSS side) (rpm) [used only when VSContrl=1]
             VS_RtTq     - Rated generator torque/constant generator torque in Region 3 for simple variable-speed generator control (HSS side) (N-m) [used only when VSContrl=1]
             VS_Rgn2K    - Generator torque constant in Region 2 for simple variable-speed generator control (HSS side) (N-m/rpm^2) [used only when VSContrl=1]
             VS_SlPc     - Rated generator slip percentage in Region 2 1/2 for simple variable-speed generator control (%) [used only when VSContrl=1]

The reason for asking these question is that I encountered an error while running: ‘FAST_Solution:FAST_AdvanceStates:SrVD_UpdateStates:CalculateTorque:u%HSS_Spd is negative. Simple variable-speed control model is not valid for motoring situations.’ What does this error mean?

Thanks in advance for any help.

Best regards,
Chen

2

Dear @Rugang.Chen,

Here are my responses:

  • OpenFAST only supports linearization with simple built-in generator or control models enabled (not user-defined controllers implemented in Simulink or DISCON dynamic libraries).
  • For documentation on the simple variable speed controller of ServoDyn, please find documentation in the old FAST v6 User’s Guide: .https://openfast.readthedocs.io/en/main/_downloads/d8bd014121d6505cb25cf49bee5eaa80/Old_FAST6_UsersGuide.pdf (particularly Figure 22 the associated text).
  • The error about “motoring” means that the simple variable speed controller is not valid when the generator speed is negative.

Best regards,