Interdependant and Calculated Variables for Windpower model

Hello,
I am currently working on a project that involves PySAM. I am trying to systematically optimize the inputs of a windpower model in the context of a larger simulation. PySAM's documentation states, that there are a number of interdependant and calculated variables for each model. Sadly the links in the provided example are outdated, as the files have been converted to json. Could you give me a nudge in the right direction or even provide me with a resource of the equations used to calculate the interdependant variables?
Best regards and many thanks for your answers in advance,
Julius

Hi Julius,

The interdependent variables for the wind power model (Windpower module in PySAM) depend on what options you choose. Can you tell me what variables you want to modify for your analysis so I can help you identify the interdependent variables?

One example is the system nameplate capacity ('system_capacity') which depends on the turbine capacity and number of turbines. For example, to set 'system_capacity' to 5 MW for a system with two 2.5 MW turbines, you would need to set the values of three variables (you can't just change the value of 'system_capacity'):
Also, can you tell me where those broken links are so we can fix them?

Best regards,
Paul.

Hey Paul,
Thanks for your quick response and sorry for my late answer! First of all, the link seems to work again! (The link to "PV System Design.txt" at the bottom of this page nrel-pysam.readthedocs.io/en/main/interdependent-variables.html did not work for me before) I am simulating a microgrid. I attached a windpower model via PySAM. I am trying to automatically optimize the windpower configuration to minimize the delta between energy produced and energy consumed in the microgrid. In order to effectively optimize the configuration of the wind park I need to define constraints for each variable. I am trying to understand which variables I can set independently and wich are calculated from the other ones or are dependant from one another. After some consideration I think the best approach would be to optimize the hub height, number of turbines and the way these turbines are laid out. Is there something to take into consideration with this approach? Also, if I am, in a second step, trying to automatically choose the right turbine, will I find all the necessary values for each kind of turbine in the "Wind Turbines.csv" in the libraries folder?
Thanks again for your effort and best regards,
Julius

Hi Julius,

The description of 'wind_turbine_hub_ht' in the documentation of the Windpower module lists two dependent variables:
'wind_turbine_powercurve_powerout' and 'wind_turbine_powercurve_windspeeds'. This is because there is a relationship between the wind turbine power curve data and the height above the ground determined by 'wind_turbine_hub_ht'. If you change the turbine hub height, you may also need to change the power curve data. Depending on the purpose of your analysis, you could choose to ignore this relationship.

Similarly, the description of 'wind_farm_xCoordinates' and 'wind_farm_yCoordinates' mentions a dependence on rotor diameter: The turbines should be spaced to minimize wake effects and avoid the risk of blades from neighboring turbines touching each other.

And, yes, the Wind Turbines.csv turbine library file has the power curve data, power rating, and rotor diameter data you need to model the turbines in the library. Note that the power curve data is separated by pipes '|', so you'll need to consider that when you process the data. The library file does not include turbine hub heights. The turbine name and IEC class are not inputs to the Windpower model, so you can ignore those parameters.

Best regards,
Paul.

Hi Paul,
Thank you for your help and advice! I really appreciate it. In the SAM Desktop app, one can check "Specify desired farm size" under "System Sizing". This automatically generates a turbine layout from just the "Desired farm size" input. How are these layouts generated? I am having trouble finding the corresponding function in the GitHub repo. Could you possibly link me to it?
Thanks again for your kind support and best regards,
Julius

Hi Julius,

The wind farm sizing options are part of the SAM user interface and are not available in SSC or PySAM.

SAM's user interface uses the LK scripting language for these kinds of functions: sam.nrel.gov/lk-script.html

The LK source for the "Specify desired farm size" is here: github.com/NREL/SAM/blob/1ed59e9b181cf1f23d7ac1f696b5cb91805c7936/deploy/runtime/ui/Wind%20Farm%20Specifications.json#L2115

That's a bit difficult to read because of the '\t' escape characters, but hopefully you can copy the code to a text editor and remove those to make it easier to read.

You should be able to use that as a basis to write your own code on Python to do the turbine layout.

Best regards,
Paul.