# Using WISDEM for calculating the cost of a scaled reference turbine

Hi all,

I am an MSc student at Delft University of technology, currently working on my thesis. I have been trying to understand WISDEM for a few weeks now, but can not quite figure it out yet. I am wondering what the minimum inputs are the model needs in order for it to run? I have looked at the ontology (.yaml) files and am wondering if it is possible to leave a lot of the file empty? Will WISDEM calculate it for me if I do leave something empty?

I want to achieve something along with the following:

1. Take a reference turbine, for instance the IEA 15MW turbine.
2. Change its rated power and rated windspeed to desired values
3. scale the turbine geometry using simple scaling laws
4. Input new scaled geometry into WISDEM
5. get WISDEM to output cost,mass etc. of scaled turbine components

I would like to know if this is at all possible and how I should go about this. I have looked through a lot of the documentation, but can’t find the answers to my questions. If more info is needed, let me know!

Kind regards,

Bas Vos

Hello,

Thank you for your interest in WISDEM. We have some relatively recent examples and documentation that should help you accomplish what you intend.
However, this reply comes with a warning that just because you can scale a geometry, doesn’t mean that you are working with an optimized design.

To start with running the IEA Wind 15MW reference turbine, use the files located in this example:
https://github.com/WISDEM/WISDEM/tree/master/examples/02_reference_turbines

And follow the instructions in the Documentation:

To scale the turbine to a different rated power, rotor diameter, and hub height, change the entries in the top “assembly” section of the geometry yaml file, IEA-15-240-RWT.yaml and save to a new file name:

``````assembly:
turbine_class: I
turbulence_class: B
drivetrain: direct_drive
rotor_orientation: Upwind
hub_height: 150.
rotor_diameter: 242.23775645
rated_power: 15.e+6``````

Now you can run this file in WISDEM in the same way as before. I would recommend changing the output filename in the “analysis_options.yaml” file so that you do not overwrite the baseline outputs. You mentioned rated wind speed, as well, but this is an output, based on blade aerodynamic shape, tip speed ratio, rated power, etc.

Just because the turbine is scaled, does not mean you will get optimal results for mass, AEP, cost, and overall LCOE. With new rotor diameters and rated power values, you should consider re-optimizing the blade and tip speed ratio too, depending on how big of a change you have made. As the loads change, you would need to re-optimize the drivetrain components and support structure as well.

Hope this helps,
Garrett

Hi Garret,

I have now run WISDEM according to the instruction, in two different directories so they do not overwrite. I have looked through the output file, but I can not seem to find the answers I am looking for. For instance, when changing the rated power, the output file does not seem to contain any changes, besides the value for rated power.
I also can not find where the outputs are stored that are printed in the terminal after a simulation has run (turbine AEP, Blade mass etc.)? They do not seem to be in the output file.

The goal of my study is not to find an optimal turbine design, but to (roughly) determine the cost of a new turbine design (one with low rated power, rated windspeed around 7m/s and cut out around 13 m/s for instance).
Is it possible to:

1. manually scale the blades to the desired length, adjust chord and twist using scaling laws, to accommodate for changes in TSR and rotor diameter.
2. input this scaled blade and new desired rated power in WISDEM
3. have WISDEM give me rotor aerodynamic performance (power curve, cp-lambda). nothing fancy is needed here, just to show if the turbine operates at optimum cp, and has the desired power curve.
4. have WISDEM scale other components (generator, tower dimensions etc.)
5. have WISDEM output the cost of this new turbine

I am obviously very new to turbine design. Hope you can help me

Hi Bas,

For the outputs, there should be a .mat, .npz, and .xlsx file that have the WISDEM outputs all listed. I acknowledge that the variable listing in long and it can sometimes be difficult to find what you are looking for. In the xlsx-file, you should definitely be able to search for terms such as ‘lcoe’, ‘aep’, ‘cost’, etc.

In regards to what you are trying to accomplish:

1. I am not aware of scaling laws to give you better estimates on chord and twist profiles. Those are dependent on airfoil selection, tip speed ratio, design point, etc.
2. WISDEM can definitely give you those outputs, but as I mentioned in the prior post, you should not assume that you are operating at the optimal Cp. You would have to re-optimize the blade for that.
3. WISDEM will scale other components only through a design optimization. If you are looking for automatic sizing based on empirical (i.e. regression) fits, you may find an easier path using the NREL Cost and Scaling Model. This is accessible through WISDEM as a standalone code (see examples: https://wisdem.readthedocs.io/en/latest/examples/nrelcsm/tutorial.html) or through the NREL SAM application (https://sam.nrel.gov/), which is much more user-friendly.

Cheers,
Garrett