Calculation of loads on the foundation. Training materials

[Blackranger323]

Good afternoon!
Our company is just taking the first steps into wind turbine configuration management. Faced with the problem of calculating the loads on the foundation when changing the blades of our 2.5 MW installation. The blade length has been increased from 49.5 to 51 meters. Can you tell me which codes contained in the repository can be used to solve this problem? And perhaps somewhere on the forum there are already articles and guidelines that could be used to learn how to perform such calculations. This is the first time we have encountered such a task. Before that, only small wind turbines were considered according to building regulations. Thank you in advance

[jjonkman]

Dear @Blackranger323,

When you change the blade length, do you fully know the blade aerodynamic and structural properties such that you can make an aero-elastic model in OpenFAST? Do you have the properties of the rest of the system (drivetrain, nacelle, tower, controller) to complete this OpenFAST model? If so, you can make this OpenFAST model and run the necessary simulations to calculate the change in system response and loads throughout the system (including the foundation), based on the load cases laid out in design standards, e.g., IEC 61400-1.

Best regards,

[jjonkman]

Dear @Blackranger323,

If you don't have all of the properties needed to make an OpenFAST model, you'd have to fill in these gaps someway.

The controller is often the hardest to fill in if you don't have it. If the controller is the key gap you have, a calibrated ROSCO controller is often a good substitute: https://github.com/NREL/ROSCO.

Depending on the gaps you have (especially if they are extensive), NREL has inverse design capability that can be used to fill in the gaps, e.g., as mentioned in the following OpenFAST issue: #2991.

But is is hard to offer specific guidance without knowing more about your use case, including what information you have and don't have about your turbine.

Best regards,

[Blackranger323]

Dear @jjonkman,
We are dealing with a fairly old wind turbine with a capacity of 2.5 MW. Modular steel tower with a height of 96.7 meters. Now we are considering changing the design of the blades, the length will change from 49.5 to 51 meters. Basically, my question is whether any methodological recommendations have been developed for new users of the program regarding the task of calculating loads on the foundation. This would greatly simplify the first steps in mastering the software and solving our problem.

[jjonkman]

Dear @Blackranger323,

As I mentioned in my original post, OpenFAST can certainly be used for your use case of determining the impact of a blade change on foundation loads, as long as you have the aero-servo-elastic properties needed to make the OpenFAST models. But before you can solve your desired problem, you'll have to solve the problem of filling in the data gaps you likely have so that you can make the OpenFAST models. Solving this problem will depend on what data gaps you have.

Best regards,

[Blackranger323]

Is there a manual with examples of performing these calculations available in the public domain? If so, I would appreciate a link to it.

[jjonkman]

I'm not sure if you are referring to the use of OpenFAST to compute foundation loads or to the problem of filling in the data gaps. For the former, I'm not aware of a specific document tied to your exact use case (of comparing loads for two different blades), but there are certainly more general papers on the application of OpenFAST to wind turbine loads analysis. For example, Chapter 5 of my PhD thesis-turned NREL report (https://docs.nrel.gov/docs/fy08osti/41958.pdf) explains the original loads analysis we performed for the NREL 5-MW baseline wind turbine (ignore the offshore parts of that discussion, not applicable for land-based systems).

Best regards