Wind turbine spectacular failure

[LCHIEN]

http://www.youtube.com/watch?v=7nSB1SdVHqQ

Apparently this wind turbine in Denmark had the governor mechanism (wind brakes) fail during high winds and it flew apart.

I guess that shows that wind power is not necessarily a piece of cake.

[JR]

Wow, that really shows the power wrapped up in one of those things, doesn't it?

JR

[Kristofor]

Impressive. I'm surprised they rely on braking to keep them under control. Seems like they could alter the pitch on the blades or use some sort of transmission system to add generating capacity when the wind was blowing harder.

That said, I'm not sure this is very uncommon.

Killing time in Los Angeles between two weeks of meetings a couple years ago I drove out to Joshua Tree National Park to do some hiking over the weekend.

On the way there is a large collection of (seemingly very small) wind turbines. I saw two that appeared to have damaged themselves. These weren't single pole mast style like the big ones I've seen in this neck of the woods (similar to the video), but rather metal lattice towers. One was snapped just below the turbine with lots of mangled metal and no trace of the powerhead. The other one had snapped 2 of the supports and was bent over hanging bent at odd angles on the other two.

I don't know if there had recently been a big storm or if it just wasn't cost effective to clean them up when there were working units on both sides...

Kristofor.

[LCHIEN]

basically there are several ways to limit the speed of these things. If the rotational speed gets too large then the centrifugal forces and the imbalance forces will probably tear any large rotating machine apart.

One thing that limits the speed is the load.. like a motor in reverse, the more the attached generator is loaded the slower the rotor will turn. in real power generation the simplest way to generate AC power is with a generator turning at the same speed as the line voltage in the grid you are tied to. So the big wind turbines should all turn at the same rate. You can govern the speed and or forces by feathering the pitch on the props. Normally in a good stiff wind you would feather the prop until it matched the frequency of the line power but pushed enough to source curret into the grid. Thus the feathering is the prime means of braking or governing the speed.

However in this case I'm thinking that the computer that ran the thing or the mechanism that actually feathered the props failed or even the generator failed which slows the props by its loading and the props ran away.

I would imagine any of the three (generator load, prop pitch mechanism or computer control) are not infallible so there must be a mechnical backup, maybe a plain old friction brake which also must have failed.

[leehljp]

I don't think it was the centrifugal force as it related to speed that caused the disintegration. If you look real close at the frame of and just after the disintegration, you will see a huge dent in the tower at the point it starts its buckle.

The blade was flexing and hit the tower itself. The closer video shows it better than the one from a distance.

[Crash2510]

I don't think it was the centrifugal force as it related to speed that caused the disintegration. If you look real close at the frame of and just after the disintegration, you will see a huge dent in the tower at the point it starts its buckle.

The blade was flexing and hit the tower itself. The closer video shows it better than the one from a distance.

Lee I think if you watch the slo mo you will see that the end of the blade actually explodes before hitting the mill causing a chain reaction like it was hit by a large gust

http://www.youtube.com/watch?v=lvvRH...watch_response

[Tom Slick]

if you watch closely one blade breaks then the head immediately tilts down. one blade strikes the post and everything comes apart.
It doesn't seem to have a load on it and it certainly doesn't have the blades feathered.

[IBBugsy]

Small world. A fraternity brother of mine works for that company and they are looking for more engineers. He comically sent me the video to say they hope the new engineers will help prevent this from happening again.

[BobSch]

Small world. A fraternity brother of mine works for that company and they are looking for more engineers. He comically sent me the video to say they hope the new engineers will help prevent this from happening again.

Did he mention if the original engineers were in the gen housing when it went?

[Tom Slick]

I talked to a friend of mine today that used to work on wind turbines. he says this is a fairly common occurrence. technology is changing fast enough that it is not economical to maintain older units that need significant maintenance. letting them self-destruct is an easy way to start the demolition process. That is a "small" unit, they are all getting replaced.

He also mentioned that they are only speed regulated by load and blade pitch. the brake mechanism is only to hold the rotor in a fixed position for maintenance.