Parked turbine simulation

Dear Jason,

I have question about the parked turbine simulation with FAST v8. I am trying to model a parked turbine with NREL 5MW Land-based (ref. to FAST CertTest 18), under constant wind speed 30m/s. Since there were many discussions about the extreme event/parked simulation in the forum already, so I would like to confirm if I am well understood from those discussions:

  1. refer. to the FAST user guide https://nwtc.nrel.gov/system/files/FAST.pdf, the parked turbine have been described with different cases (full-span pitch and HSS brake), is it correct if i adapted the HSS brake for the NREL 5MW due to its gross properties, which is refer to https://www.nrel.gov/docs/fy09osti/38060.pdf

  2. if i would like to park the wind turbine by apply a HSS brake due to the its gross properties, the significant parametres could be changed as follows:
    ServoDyn
    PCMode = 0
    VSControl = 0
    GenTiStr = True
    TimeGenOn = 9999.9
    HSSBrmode = 1
    THSSBrDP = 0
    HSSBrDT = 0
    HSSBrTqF = 28116.2 (it seems a default factor in the Test18)

ElastoDyn
for the DOFs part, there are only GenDOF, DrTrDOF and YawDOF changed into false, the rest of the DOFs remain unchanged refer to the Test18
BlPitch1&2&3 (initial pitch of blade 1-3) = 90, to ensure the blades are feathered
rotorspeed = 0

AeroDynv15
WadeMod = 0
AFAerMod = 1

  1. In one of the extreme events discussion, you have mentioned modelling with and idling rotoris more common for an extreme event simulation, does it applicable for the parked turbine too? Many Thanks.
    relative post :
    http://forums.nrel.gov/t/aerodyn-feedback/57/1

Best regards,
Kylee

Dear Kylee,

I agree with your settings, except:

  • There is no reason to disable the drivetrain-torsion (DrTrDOF) and nacelle-yaw (YawDOF) degrees of freedom when parked.
  • There is no reason to both apply the high-speed shaft brake (HSSBrMode=1) and to disable the generator DOF (GenDOF=False); when GenDOF is disabled, the torques applied cannot accelerate or decelerate the generator. If you want to model possible slip of the brake, I would enable GenDOF while applying the brake.

Regarding (3), it is not common to park the rotor of utility-scale wind turbine with a brake except during maintenance operations. Normally during high winds when the wind turbine is shut down, the rotor is left to idle (rather than parked with a brake applied) with the blades feathered.

Best regards,

Dear Jason,

Thank you for your prompt reply. May i ask for your comment on the setting for parking the turbine with full-span pitch? Given the intention of FAST user guide, PitManRa and TPitManS should be set to 0 and initial&final pitch of blades should be set to 90 , what about GenDOF? is it required for disable ? Many Thanks.

BR,
Kylee

Dear Kylee,

Regarding the blade pitch, yes, you can do as you said. Equivalently, you can also set the initial blade pitch to 90 and set TPitManS > TMax.

Regarding GenDOF, you can either lock the generator by setting GenDOF=False (in which case HSSBrMode is irrelevant) or allow for possible slip of the brake by setting GenDOF=True and HSSBrMode=1. But again, most utility-scale wind turbines with full-span pitch do not engage the brake in high winds except during maintenance operations.

Best regards,

Dear Jason,

I am using openfast and I need to simulate parked condition considering steady wind speed of 3m/s. For this I have changed the servodyn and aerodyn, I have attached these files, please advice me on whether it is correct or not to setup parked condition and is there any other module that I should the input for parked condition.

Thanks,
Satish J
NRELOffshrBsline5MW_OC3Monopile_ServoDyn.rtf (11.4 KB)
NRELOffshrBsline5MW_OC3Monopile_AeroDyn15.rtf (9.19 KB)

Dear Satish,

I agree with your AeroDyn settings for parked conditions (WakeMod = 0, AFAeroMod = 1, TwrAero = True).

In ServoDyn, I see that you’ve enabled the Thevenin-Equivalent (TEC) Induction Generator model (VSContrl = 0, GenModel = 2), but you haven’t set realistic values for the TEC model. This may be OK, assuming you’ve disabled the generator degree of freedom in ElastoDyn (GenDOF = False) to park the rotor, because in that case the generator model has no effect anyway. But if you would prefer to model an idling rotor, it would be better to enable the generator DOF in ElastoDyn and disable generator torque altogether (GenTiStr = TRUE, TimGenOn > TMax).

You haven’t attached your ElastoDyn file, but presumably you’ve also initialized the rotor speed to zero (RotSpeed = 0), and you’ve likely pitched the blades to feather (BlPitch(1,2,3)) = 90 degrees).

Best regards,

Dear Jason,

Thanks for your reply.

I have changed the inputs corresponding to above post, in addition, I have attached the elastadyn module for parked condition.

Thanks,
Satish J
NRELOffshrBsline5MW_OC3Monopile_ElastoDyn.rtf (13 KB)
NRELOffshrBsline5MW_OC3Monopile_ServoDyn.rtf (11.4 KB)
NRELOffshrBsline5MW_OC3Monopile_AeroDyn15.rtf (9.19 KB)

Yes, looks good!