Understanding the power curve

[moptis]

I'm a newbie to Floris, so this answer must be very obvious. But how does a 15 MW IEA turbine, for example, have a peak power value of 0.45? Is this some scaled density value? I can't find any documentation that address this.

Thanks!

[moptis]

OK, just figured out that it's a power coefficient curve. Next question though: how is total power production at the turbine determined? There doesn't appear to be any clear indication of a 5 MW capacity in the NREL 5MW data, for example.

[moptis]

Thanks Raphael, good to hear from you too! This is all very helpful.

So for the 5 MW example, where is the turbine capacity actually specified, i.e., the 5 MW? I'd like to create my own turbine type and can create the power and thrust coefficient curves easy enough. But it's not clear how to assign total turbine capacity.

For what it's worth, from an industry perspective, I'm interested in using FLORIS to find optimal offshore layouts. I'd be happy to keep a thread going on my experiences and where I think more documentation might be useful.

Mike

[rafmudaf]

The turbine capacity is implicit in the power curve. These are generally gotten from a tool like OpenFAST. That's why the power curve flatlines at 5MW, for example. There are no turbine controls in FLORIS (like blade pitch control), but there is a controller in OpenFAST that holds the power at rated in region 3. So you won't find a place in floris to enter "5MW", but that information should be included in the Cp/Ct vs wind speed table.

[rafmudaf]

For what it's worth, from an industry perspective, I'm interested in using FLORIS to find optimal offshore layouts. I'd be happy to keep a thread going on my experiences and where I think more documentation might be useful.

Please do stay in touch on that. We have similar efforts at NREL, so if want to discuss in more detail just get in touch. My email address is on my GitHub profile (github.com/rafmudaf).

[moptis]

Ah ok, makes sense, thanks Raphael.

My confusion came from the use of Cp data in the turbine library rather than actual power output in kilowatts. I'm just not used to seeing Cp. Turbine manufacturers always provide us power output and Ct data and we're generally left to calculate Cp ourselves.

I'm good to go from here. Thanks again.

[paulf81]

Thanks for this discussion, just to add a few quick comments of my own here:

• Make sure Cp is "electrical" Cp (in the FAST terminology) meaning it has shaft and generator efficiencies "baked in" and the final output is for example, the exact rated power you expect
• I've found the example 15_check_turbine.py really useful in doing a last sanity check on your input file
• I've gone through this process a few times (mocking up a FLORIS input of a new turbine given just a few descriptors, adapting from the 5MW or 15MW for example), maybe some included function that automates this would help going forward?