Are wind turbines protected against lightning? 1

[droog]

I was thinking about wind turbines and suddenly noticed that the big rigs, like the ones utility companies are adopting, are usually higher than anything else around them. Furthermore, the motion of the blades causes friction with the air which could conceivably create static charges. If such is the case, wind turbines serve as de facto lightning rods and have electrical charges of their own that can make them more prone to lightning strikes.

Am I right on this? If so, what type of protection is used and where is it placed? Going by pictures on magazines, I've never seen lightning rods in wind farms.

 

[windie]

New wind turbines with blade lengths of more than about 20 metres have metallic receptors near the tips (ends) of the blades. The receptors are connected to cables that run down the length of blades. There are often also lightning rods at the back of the wind turbine nacelle (box). The lightning is conducted through the turbine and tower (and around bearings) and into an ground (earth) grid at the bottom of the turbine.

Different turbine manufacturers use different implementations of this scheme.

 

[rsherry]

One of the first offshore wind turbines in the UK (at Blyth) has been struck by lightning. It broke one of the blades, I don't know how much info has been made public about it - I know no more about it.

 

[ScottyUK]

Hi rsherry,

Are you up in the North-East too? I remember the forlorn-looking turbine with the blade missing. It had only been in service a year or two. I have no further info either - smells like a cover-up!



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If we learn from our mistakes,
I'm getting a great education!

 

[windie]

In reference to the posts by rsherry and scottyuk - even a wind turbine with a lightning protection system can get damaged by lightning. The protection system reduces the risk of damage, but if the lightning doesn't hit right on the receptor or you get a really big strike (e.g. >200 kA) you are still going to get some damage.

 

[cuky2000]

I believe there is not lightning standard in the USA at this moment applicable to wind farms. Several incidents associated with lightning damages to wind turbine had been recorded . However, the damages caused by lightning are in decline perhaps because
modern wind turbine blades are manufactured of none conductive materials such as reinforced plastic, wood laminated and similar combinations.

Most damages caused by lightning to wind turbines assembly are primarily associated with control system, power system components, mechanical elements, blades and others. Even though blades damages are around 10% with the downtime and cost to get back online could be significant.

The electrogeometric model for lightning protection, may be help to provide a mitigation alternative for lightning protection applicable to wind farms

 

[rsherry]

Thanks for the background windie, presumably turbines could be protected by overhead earth wires or just higher structures nearby with earth connections - although I havent heard of anyone doing this. Offshore this may make some economic sense given the likely down time from any strikes.
Yes Scotty i'm on Tyneside. I was at Teeside briefly during the commissioning when I was working for NGC, hope it's still running OK!

 

[droog]

Thanks for info and illustration.

 

[windie]

rsherry

Modern wind turbines are often in excess of 100metres high. Something to intercept the strikes before they reach the wind turbines would have to be even higher. To provide protection using external structures would be expensive. So far it is cheaper to put a copper cable inside the blades and existing wind turbine structure ... but if you can come up with something better ...