How can I move the thrust peak?

[rhaghi]

Hi,

I have access to a turbine measurement campaign data and am trying to build an openFAST model for it. I used WISDEM (mainly rostor.se) to make the aerodynamic model, and then WISE to convert the WISDEM output to an OpenFAST model. The challenge that I am facing is tuning ROSCO to match the control behavior of the turbine that I have at hand. This is part of my ROSCO yaml file:

-------------------------------- TURBINE PARAMETERS -----------------------------------
turbine_params:
rotor_inertia:
rated_rotor_speed:
v_min: 3.0 # Cut-in wind speed [m/s] RH: Based on the data on the measurement
v_rated: 10.5 # Rated wind speed [m/s] RH: Based on the data on the measurement
v_max: 25 # Cut-out wind speed [m/s], -- Does not need to be exact (JUST ASSUME FOR NOW)
max_pitch_rate:
max_torque_rate:
rated_power:
bld_edgewise_freq:
bld_flapwise_freq:
------------------------------- CONTROLLER PARAMETERS ----------------------------------
controller_params:
LoggingLevel: 0 # {0: write no debug files, 1: write standard output .dbg-file, 2: write standard output .dbg-file and complete avrSWAP-array .dbg2-file
F_LPFType: 1 # {1: first-order low-pass filter, 2: second-order low-pass filter}, [rad/s] (currently filters generator speed and pitch control signals)
F_LPFDamping: 0
F_NotchType: 0 # Notch filter on generator speed and/or tower fore-aft motion (for floating) {0: disable, 1: generator speed, 2: tower-top fore-aft motion, 3: generator speed and tower-top fore-aft motion}
IPC_ControlMode: 0 # Turn Individual Pitch Control (IPC) for fatigue load reductions (pitch contribution) {0: off, 1: 1P reductions, 2: 1P+2P reductions}
VS_ControlMode: 1 # Generator torque control mode in above rated conditions {0: constant torque, 1: constant power, 2: TSR tracking PI control}
VS_ConstPower: 1
PC_ControlMode: 1 # Blade pitch control mode {0: No pitch, fix to fine pitch, 1: active PI blade pitch control}
Y_ControlMode: 0 # Yaw control mode {0: no yaw control, 1: yaw rate control, 2: yaw-by-IPC}
SS_Mode: 1 # Setpoint Smoother mode {0: no setpoint smoothing, 1: introduce setpoint smoothing}
WE_Mode: 2 # Wind speed estimator mode {0: One-second low pass filtered hub height wind speed, 1: Immersion and Invariance Estimator (Ortega et al.)}
PS_Mode: 3 # Pitch saturation mode {0: no pitch saturation, 1: peak shaving, 2: Cp-maximizing pitch saturation, 3: peak shaving and Cp-maximizing pitch saturation} RH: Changed to 2 as it seems it is active on SWT-6.0 based on the measurements (check pitch vs wind speed)
SD_Mode: 0 # Shutdown mode {0: no shutdown procedure, 1: pitch to max pitch at shutdown}
Fl_Mode: 0 # Floating specific feedback mode {0: no nacelle velocity feedback, 1: nacelle velocity feedback}
Flp_Mode: 0 # Flap control mode {0: no flap control, 1: steady state flap angle, 2: Proportional flap control}
PwC_Mode: 0
TSR_operational: 8 # Desired below-rated operational tip speed ratio (Cp-maximizing TSR is used if not defined) RH: This needs to be tuned
zeta_pc: 0.7 # Pitch controller desired damping ratio [-]
omega_pc: 0.5 # Pitch controller desired natural frequency [rad/s]
zeta_vs: 0.7 # Torque controller desired damping ratio [-]
omega_vs: 0.15 # Torque controller desired natural frequency [rad/s]
twr_freq: 0.4499 # Tower natural frequency [rad/s]
ptfm_freq: 0.2325 # Platform natural frequency [rad/s] (OC4Hywind Parameters, here)
ps_percent: 0.70 # Percent peak shaving [%, <= 1 ], {default = 80%}
sd_maxpit: 0.4363 # Maximum blade pitch angle to initiate shutdown [rad], {default = bld pitch at v_max}
DISCON:
PS_Mode: 0

I can't show the whole yaml file as I can't reveal anything about the turbine. I attached the OpenFAST output compared with the measurement here as well. They are normalized.

How can I move the wind speed that FA moment peaks from 10 m/s to 11.5m/s or 12 m/s? The same question is valid for the pitch. I want the turbine to start pitching out at 11.5m/s or 12m/s?

Thanks a lot for the help!

[dzalkind]

Hi,

The controller probably shouldn't be used to move the peak of the thrust curve (or the knee of the power curve). The controller can be used to change the maximum thrust using peak shaving, which it looks like you are disabling with the very last part of your tuning yaml:

DISCON:
    PS_Mode: 0

Since the peak thrust and rated power are occurring earlier in the OpenFAST model than the measurements, that indicates that the OpenFAST model is capturing more energy than the actual turbine. You could reduce the power of the OpenFAST model by changing the pitch angle below rated, or you could change the model to better match the power (by making the blades shorter, reducing the chord, or increasing the twist). @ptrbortolotti is the expert on tuning the WISDEM/OpenFAST model, any ideas?

I hope this helps.

Best, Dan

[ptrbortolotti]

I am not too sure... @rhaghi how confident are you in the wind speed signal? the measurements indicate that blades start pitching between 11 and 12 m/s, but thrust would skyrocket if you were to pitch so late. can you maybe plot rotor rpm and see if you got the right TSR and rated omega?