Dear all,
I am studying an optimization problem for a floating wind turbine. I have used the example at link , using RAFT for the computation of the FOWT response.
I have tried to run two different optimization considering the column draft and radial distance from central column as design variables. The two optimization runs differ in the range of variation of the design variables: the first one has a smaller variation range than the second one. The final configurations have different masses (with a difference of about 12%), the estimated AEP remains unchanged between the two final designs, however, the LCOE values reported among the “financese” variables are the same for both cases. I am not sure if the LCOE estimation performed in financese is insensitive to platform mass calculation? I report the analysis options and modeling options below.
general:
folder_output: outputs/15_RAFT_Rect
fname_output: refturb_outputdesign_variables:
control:
servo:
pitch_control:
omega:
flag: True
min: 0.1
max: 0.5
floating:
joints:
flag: True
z_coordinate:
- names: [main_keel, col1_keel, col2_keel, col3_keel]
lower_bound: -40.0
upper_bound: -10.0
r_coordinate:
- names: [col1_keel, col1_freeboard, col2_keel, col2_freeboard, col3_keel, col3_freeboard]
lower_bound: 38.8125
upper_bound: 64.6875
# members:
# flag: True
# groups:
# - names: [column1,column2,column3]
# diameter:
# lower_bound: 9.375
# upper_bound: 15.625
# constant: True
# thickness:
# lower_bound: 0.05
# upper_bound: 0.25
# constant: True
# - names: [Y_pontoon_lower1, Y_pontoon_lower2, Y_pontoon_lower3]
# diameter:
# lower_bound: 7.5
# upper_bound: 12.5constraints:
control:
rotor_overspeed:
flag: False
min: 0.0
max: 0.25
Max_PtfmPitch:
flag: True
max: 5.5
Std_PtfmPitch:
flag: True
max: 2.
Max_Offset:
flag: True
max: 30.
floating:
stress:
flag: True
global_buckling:
flag: True
shell_buckling:
flag: Truemerit_figure: platform_mass # Merit figure of the optimization problem. The options are ‘AEP’ - ‘LCOE’ - ‘Cp’ - ‘blade_mass’ - ‘blade_tip_deflection’
driver:
optimization:
flag: True # Flag to enable optimization
solver: LN_COBYLA # Optimization solver. Other options are ‘SLSQP’ - ‘CONMIN’
tol: 1.e-2 # Optimality tolerance
max_iter: 50 # Maximum number of iterations (SLSQP)design_of_experiments:
flag: True # Flag to enable design of experiments
run_parallel: False # Flag to run using parallel processing
generator: LatinHypercube # Type of input generator. (Uniform)
num_samples: 12 # number of samples for (Uniform only)
recorder:
flag: True # Flag to activate OpenMDAO recorder
file_name: log_opt.sql # Name of OpenMDAO recorder
includes: [‘raft’,‘floating’,‘platform’]
General:
verbosity: False # When set to True, the code prints to screen many infos
openfast_configuration:
use_exe: True
allow_fails: True
fail_value: 9999WISDEM:
RotorSE:
flag: True
spar_cap_ss: Spar_Cap_SS
spar_cap_ps: Spar_Cap_PS
te_ss: TE_reinforcement_SS
te_ps: TE_reinforcement_PS
TowerSE:
flag: True
DriveSE:
flag: True
FloatingSE:
flag: True
# BOS:
# flag: TrueLevel3: # Options for WEIS fidelity level 3 = nonlinear time domain
flag: False
simulation:
DT: 0.01
CompElast: 1
CompInflow: 1
CompAero: 2
CompServo: 1
CompHydro: 1
CompSub: 0
CompMooring: 3
CompIce: 0
OutFileFmt: 3
linearization:
Linearize: False
ElastoDyn:
FlapDOF1: True
FlapDOF2: True
EdgeDOF: True
TeetDOF: False
DrTrDOF: False
GenDOF: True
YawDOF: False
TwFADOF1 : True
TwFADOF2 : True
TwSSDOF1 : True
TwSSDOF2 : True
PtfmSgDOF: True
PtfmSwDOF: True
PtfmHvDOF: True
PtfmRDOF : True
PtfmPDOF : True
PtfmYDOF : True
HydroDyn:
WvLowCOff: 0.15708
WvHiCOff: 3.2
WaveSeed1: 123456789
AddBQuad1: [9.23e5, 0.0, 0.0, 0.0, -8.92e6, 0.0]
AddBQuad2: [0.0, 9.23e5, 0.0, 8.92e6, 0.0, 0.0]
AddBQuad3: [0.0, 0.0, 2.3e6, 0.0, 0.0, 0.0]
AddBQuad4: [0.0, 8.92e6, 0.0, 1.68e10, 0.0, 0.0]
AddBQuad5: [-8.92e6, 0.0, 0.0, 0.0, 1.68e10, 0.0]
AddBQuad6: [0.0, 0.0, 0.0, 0.0, 0.0, 4.8e10]
PotMod: 1
# WaveMod: 0Level1:
flag: True
potential_model_override: 0
trim_ballast: 2
heave_tol: 1
save_designs: TrueROSCO:
flag: True
SD_Mode: 0
PS_Mode: 1
ps_percent: 0.85
F_LPFType: 2
F_NotchType: 2
Fl_Mode: 2
tuning_yaml: …/…/examples/01_aeroelasticse/OpenFAST_models/IEA-15-240-RWT/IEA-15-240-RWT-UMaineSemi/IEA15MW-UMaineSemi.yaml
zeta_pc: [1]
omega_pc: [0.2]
U_pc: [12]
zeta_vs: 0.85 # Torque controller desired damping ratio [-]
omega_vs: 0.12
twr_freq: 3.2
ptfm_freq: 0.2
Kp_float: -10DLC_driver:
metocean_conditions:
wind_speed: [4., 6., 8., 10., 12., 14., 16., 18., 20., 22., 24.]
wave_height_NSS: [0.83, 0.88, 0.94, 1.03, 1.16, 1.34, 1.57, 1.86, 2.22, 2.62, 3.07]
wave_period_NSS: [6.9, 6.96, 7.02, 7.12, 7.25, 7.43, 7.66, 7.94, 8.27, 8.63, 9.01]
wave_height_SSS: [6.3, 8, 8, 8.1, 8.5, 8.5, 9.8, 9.8, 9.8, 9.8, 9.9]
wave_period_SSS: [11.5, 12.7, 12.7, 12.8, 13.1, 13.1, 14.1, 14.1, 14.1, 14.1, 14.1]
wave_height1: 6.98
wave_period1: 11.7
wave_height50: 10.68
wave_period50: 14.2
DLCs:
- DLC: “1.1”
n_seeds: 1
# - DLC: “1.3”
# n_seeds: 6
- DLC: “1.4”
- DLC: “1.5”
- DLC: “1.6”
n_seeds: 1
- DLC: “6.1”
n_seeds: 1
# - DLC: “6.3”
# n_seeds: 6
I also noticed that in the generated output file the units reproted for the variable financese.plant_aep are USD/kW/h. Is this correct?
Moreover, I am not sure about the meaning of the “constant” keyword in the design variable in the member diameter and thickness. Does it constrain the diameter or thickness to be constant along member axis? Setting this parameter to false, the run terminated with the following error.
Thanks in advance for your support.
Best regards,