Linearization OpenFAST Region 2

Wind & Water Computer-Aided Engineering Software Tools
2

Dear @Daniel.Aldaz,

Just a couple comments:

  • The FAST v7 User’s Guide only recommends setting constant torque for TrimCase = 3 (linearization of blade pitch in Region 3). For TrimCase = 2 (linearization of generator torque in Region 2 with fixed blade pitch), the generator torque is assumed to be calculated via the trim controller rather than with an internal torque controller in ServoDyn. So, effectively, you want ServoDyn to return zero torque. This can be achieved by setting in ServoDyn GenTiStr = True and TimGenOn > TMax, where TMax is the maximum simulation time set in the OpenFAST primary (.fst) input file.
  • While the trim controller will calculate the generator torque needed to reach a steady-state solution, it is not tracking generator power. So, the ServoDyn output GenPwr will be calculated using the internally selected generator model (GenPwr = 0 when GenTiStr = True and TimGenOn > TMax) regardless of the actual generator torque set by the trim controller. So, I wouldn’t rely on ServoDyn output GenPwr being accurate when enabling a trim solution.

I’m aware of the LiDAR module being implemented in OpenFAST, but the pull request has not been issued yet.

Best regards,