Servodyn Stc substructure structural

Wind & Water Computer-Aided Engineering Software Tools
1

Dear @Jason.Jonkman ,

I was running simulation in OpenFast v2.1 including structural control.
If I want to fit the model, I need to get the acceleration of the mass block. OutListParameters only contain the displacement and velocity of the mass block, how can I output the acceleration
Could you please help me ?

Best regards,
Haodong Zhang

2

Dear @Haodong.Zhang,

Good point; the acceleration of the TMD is not currently output from the Structural Control (StC) submodel of ServoDyn. You could estimate it by computing the numerical derivative of the velocity, but numerical derivatives can introduce noise that you’d likely have to filter out. Alternatively, the acceleration is certainly computed internally with StC and you could always modify the source code to output this acceleration, but this would require a recompile of OpenFAST. You could also request a feature enhancement of OpenFAST through OpenFAST GitHub Issues so that this output is included in the standard release of OpenFAST, but I suspect it make take a while for NREL to get to this.

Best regards,

3

Dear @Jason.Jonkman ,
Thank you very much for your reply.
In substructure structural control, only TMD degrees of freedom in the X direction are allowed, should the value of StC_P_Z be positive or negative, and is the reference point the joint of the platform and the tower?
Best regards,
Haodong Zhang

4

Dear @Haodong.Zhang,

Just a couple comments:

  • StC supports independent TMDs in local X, Y, and Z coordinates of the body (blades, nacelle, tower, substructure) that the StC is placed, not just the X direction. An omni-directional TMDs in local X/Y coordinates is also available.
  • The origin of StC_P_Z is the origin of the body that the StC is placed (blade root for blades, yaw bearing for nacelle, tower base for tower, and platform reference point for substructure). Given that, I would guess StC_P_Z would most likely be positive.

Best regards,

5

Dear @Jason.Jonkman ,
Thank you very much for your reply.
Sorry, my expression is wrong, I only allowed TMD degrees of freedom in the X direction in the simulation.
Best regards,
Haodong Zhang

6

Dear @Jason.Jonkman ,
LSSTipMya Rotating low-speed shaft bending moment at the shaft tip (teeter pin for 2-blader, apex of rotation for 3-blader) About the ya-axis (kN-m)
HydroMyi Total integrated hydrodynamic moment about the global y-axis from both potential flow and strip theory at (0,0,0)
I would like to ask, LSSTipMya and HydroMyi are towers and platforms subjected to wind and wave torque?
Haodong Zhang

7

Dear @Haodong.Zhang,

ElastoDyn output LSSTipMya is the reaction bending in the shaft at the tip about ya-axis–that is, the moment transmitted to the shaft through the rotor.

HydroDyn output HydroMyi is the total applied hydrodynamic load integrated about the platform about the yi-axis–that is, the total hydrodynamic moment applied to the platform through water.

Best regards,