Why do wind turbines pitch their blades?

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Discussion Overview

The discussion revolves around the reasons why wind turbines pitch their blades, particularly in relation to generator size and structural considerations. Participants explore the technical and economic implications of turbine design, focusing on optimization and operational efficiency.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Ian questions the rationale behind pitching blades and suggests that a larger generator could yield more energy without changing other components.
  • Some participants propose that turbines are optimized for expected wind conditions, and using a larger generator may not be economically viable due to infrequent high wind events.
  • There is a discussion about the concept of "feathering" the blades to prevent structural failure during strong winds, indicating that larger generators could lead to increased stresses on the turbine structure.
  • One participant clarifies that while a larger generator could theoretically generate more energy, it would require structural modifications to handle the increased forces.
  • Ian acknowledges the low capacity factor of wind turbines, suggesting that they do not operate at their designed wind speed frequently.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility and implications of using larger generators, with some agreeing on the need for structural considerations while others focus on economic viability. The discussion remains unresolved regarding the optimal design choices for wind turbines.

Contextual Notes

Participants reference concepts such as optimization, capacity factor, and structural integrity without fully resolving the implications of these factors on turbine design.

Ian231
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TL;DR
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
 
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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.
 
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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.
 
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anorlunda said:
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?
 
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Borek said:
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
 

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