Why do wind turbines pitch their blades?

[Ian231]

TL;DR Summary

Wind turbines seem to pitch their blades to protect the generator. Why don't they get a bigger generator instead?

Hi all.

I'm new to this forum and to wind turbine technology in general, and I watched one of these one-minute videos explaining why wind turbines pitch their blades but it doesn not make sense to me. Why don't you just get a bigger generator? You'd get more energy for the same blades, same tower, same location, etc. Or am I missing something?

Here's the video, in case my explanation does not make sense.



Thanks,
Ian

 

[Borek]

Optimization. Turbines are designed to work with the expected wind, using larger generator that would be used just for few days a year is not economically viable.

 

[anorlunda]

Your comment makes it sound like you are focused on what is called "feathering" of the blades when the wind is too strong.

You are correct that putting on a bigger generator might keep the speed down even when the wind is strong. However there are other stresses and forces that increase with more wind and more power generated. The short answer is that something may break -- structural failure.

Even things that don't rotate at all get blown down by strong winds.

 

[Ian231]

Your comment makes it sound like you are focused on what is called "feathering" of the blades when the wind is too strong.

You are correct that putting on a bigger generator might keep the speed down even when the wind is strong. However there are other stresses and forces that increase with more wind and more power generated. The short answer is that something may break -- structural failure.

Even things that don't rotate at all get blown down by strong winds.

So, if I understood you correctly, my 'same blades, same tower' was actually wrong: you could get more energy by putting a bigger generator, but you'd need to change the structure so it can handle higher stresses and forces. Did I get it right?

 

[Ian231]

Optimization. Turbines are designed to work with the expected wind, using larger generator that would be used just for few days a year is not economically viable.

Ok, that's quite interesting. I guess wind turbines do have a quite low capacity factor, which (if I undersand correctly) shows that they don't operate at the designed wind speed that often