Dear Jonson
I would like to know the mass inertia of the wind turbine (5MW) i.e whene only the GenDOF is enabled
Dear Ali,
I’m still not understanding. Do you want to know the rotor inertia about the shaft, the equivalent drivetrain inertia (rotor + gearbox + generator) about the shaft, the entire inertia of the rotor-nacelle assembly (RNA), the entire inertia of the wind turbine (RNA + tower), or something else?
Best regards,
Exactly i want the rotor inertia about the shaft
I modeled the system with: JtdOmega_r/dt=Ta/GB-Tem(Ta is the aerodynamic torque, Tem is the electromgnetic torque, GB is the gearbox and Omega_r is the rotor speed)
and Jt is the equivalent inertia of the system=Jr+GB^2Jg
So i want Jr : the rotor inertia about the low shaft
Dear Ali,
I think you meant to say: JtdOmega_r/dt=Ta-TemGB.
Regardless, when running FAST v8, the rotor inertia, Jr, is written to the ElastoDyn summary file. For the NREL 5-MW turbine, the rotor inertia is 38,759,228 kgm^2.
Best regards,
Its true
Thank you very much for your help
Best regards
Hello Jonson
A comment from your post said:
Enable me to know somes stuffs:
-If i can fixed RotSpd, Pitch and i varies the WndSpeed and then i calcultates the slop of the torque-wind speed, which is the coefficient where i searched. After i did the same for RotSpd and Pitch. My question is if this stuff is true in which values i fixed the variables (RotSpd,Pitch when we change WndSpeed;WndSpeed,Pitch when we change RotSpd;and WndSpeed, RotSpd when we change Pitch), if at the optimum values or at the initials conditions?
-Or i change arbitrary the triplet to form the 3D surface and then we conclude the slope according to each axis, if the case how many simulations can suffice to find the aerodynamic torque exerted on the Wind turbine
i would appreciate any suggestions from you
Sincerely
Dear Ali,
I’m not really sure I understand your first question.
You’ll have to do you own convergence study to determine how many simulations you need to calculate accurate slopes.
Best regards,
In order to find the torque according to wind speed and pitch, i find an difficulty in the simulations cases, it require a lot of time to change the three parameters, I asked you if there is means to perform this
And if Can you please explaine me further what is the parameters that affects the convergence study, that you said, for the 5 MW WT model
Sinceerly
Dear Ali,
I think you need to spend some time and think about the problem yourself. I will not solve the problem for you. Our software and this forum are meant for experts. We don’t have the resources to hand-hold you through the process.
By convergence, I mean that you can determine if the slope that you’ve calculated is sufficiently accurate for your needs such that adding more simulations does not improve the quality of the results (i.e. calculate the slope for each of a different numbers of simulations to determine the number of simulations necessary for the accuracy you need).
Best regards,
Dear Jonson
I means just if you are somes stuffs, its not question of expertise or waste of time for me. But in all cases thank you very much again for your response
Dear Jonson
I am wondering if
Omegar_opt=lambda_opt*VwindVxi/R is with rad/s i.e it s not worth to multiply it by pi/30 at the input of FAST, and even if this value is represents the reference rotational speed to the Wind Turbine
If possible to generate a smoooth wind profile with Turbsim, a profile without turbulence or with litle intensity
Kind regards
Dear Ali,
I’m not really sure I understand your first question. However, most rotational speed inputs to FAST are in rpm, not rad/s (see the input files or documentation for requirements on specific inputs). To convert from rad/s to rpm, you must multiply by 30/pi.
It is easy to specify wind input to FAST that is uniform or steady (without turbulence). TurbSim is not needed to input to FAST uniform or steady wind data. In FAST v8, please see the documentation supplied with the InflowWind module for instructions on specifying Steady Wind or Uniform Wind data: wind.nrel.gov/nwtc/docs/InflowWind_Manual.pdf. In FAST v7, the “uniform wind” files were called “hub-height” wind files and were entered in the AeroDyn input file instead of an InflowWind input file.
Best regards,
Thank you very much for your quick reply
About question 1 if you can clarify plus
we know that the Tip Speed Ratio is MPPT control strategy to control the system in order to extract a Maximum power.In this technique the refrence rotational speed of the speed controller is given based on the wind speed measurment Omega_ref=wind*TSR/R( I supposed that the wind speed measurment is represented by VwindVxi)
I am wondering if this is true (the wind speed measurment is represented by VwindVxi, and how about the other wind components)
And the value of the rotational speed given by the equation if it is with rpm or rad/s
Sinccerly
Dear Ali,
In the equation TSR = omega*R/V, omega should be in rad/s not rpm.
In FAST v7, WindVxi is the local wind speed at the hub height; in turbulent wind conditions, the actual wind speeds will vary across the rotor disk. While the notion of TSR is less useful in turbulent wind conditions, it would probably be the most accurate to define the wind speed, V, as the wind speed normal to the rotor disk averaged across the disk, which is how we define the equivalent output of AeroDyn v15 in FAST v8 (RtTSR).
Regardless, in an actual wind turbine variable-speed control system, the actual wind speed is not an input to the controller. Instead, a torque-speed curve (torque = K*omega^2) is developed to maximize the power capture below rated wind speed, such that the only measurement that needs to be fed as input to the controller is the generator speed. The gain (K) for the torque-speed curve can be derived from rotor radius, R, and the TSR and Cp at maximum power coefficient.
Best regards,
Thank you for your reply
I agree with you the torque controller that you mentionned is the common used as you reffered in your reference"Definition of a 5-MW Reference
Wind Turbine for Offshore System Development".However I am concerned to implmend a Tip Speed Ratio strategy based on lineraizad model to test its ability about Baseline torque controller that you have did.
In fact in this stuff, the controller need the wind speed measurment or even its approximation and the TSR optimal (which equal=7,55)
As you have mentionned
In FAST v7, WindVxi is the local wind speed at the hub height; in turbulent wind conditions, the actual wind speeds will vary across the rotor disk. While the notion of TSR is less useful in turbulent wind conditions, it would probably be the most accurate to define the wind speed, V, as the wind speed normal to the rotor disk averaged across the disk, which is how we define the equivalent output of AeroDyn v15 in FAST v8 (RtTSR).I would like to know which parameters from AeroDyn can represents the approximation of the Wind speed, you have mentionned in your post V but it didnt exist in Outlist of Aerodyn
Can be RtVAvgxh more representatif?
Dear Ali,
Yes, output RtVAvgxh from AeroDyn v15 in FAST v8 is the rotor-disk-averaged relative wind velocity normal to the disk. However, from your earlier comments I thought you were using FAST v7 with AeroDyn v13 instead of FAST v8 with AeroDyn v15. You’ll have to upgrade to FAST v8 to be able to output RtVAvgxh from AeroDyn.
Best regards,
Many thanks to you for your helps
No I am using V15 in FAST
Best regards
Ali
Tell me please what can be the cause of the problem
I listed RtVAvgxh in the Outlist of Aerodyn
I remplaced in Test18.fst the file…Onsfhore_AeroDyn by the file…Onsfhore_AeroDyn15
And when I run the simulation an error is occured indicates me that the output RtVAvgxh is not known
Sinceerly
Dear Ali,
I’m not sure. Please explain your questions more clearly.
Best regards,
In order to obtain the Rotor-disk-averaged relative wind velocity, as we said after, I listed RtVAvgxh in Output List of AeroDyn15. After that I changed “NRELOffshrBsline5MW_Onshore_AeroDyn.dat” by “NRELOffshrBsline5MW_Onshore_AeroDyn15.dat” in Test18.fst
When I conducted the simulation, an error is occured means that RtVAvgxh is not defined