Wind turbine cut in-cut out and re cut n

[tmn81]

hi everyone,

we have wind turbine which is 3 mw and operationel value is like this;

Cut-out wind speed  (100sec.exponential average) 25 m/s
Re cut-in wind speed  (100 sec. Exponential average) 20 m/s

question is can we increase this operationel value up to;

Cut-out wind speed  (10 minute exponential average) 25 m/s
Re cut-in wind speed  ( 10 minute exponential average) 23 m/s

thanks.

 

[davefitz]

I doubt it, but I am not a wind turbine expert. 10 minutes at a wind loading in excess of that deemed safe sort of invites a structural failure of the mast . There are also electrical transmission dynamics that are affected by these transients.

My guess is that you can do it once, and then you get to rebuilt the tower.

"Nobody expects the Spanish Inquisition!"

 

[davidbeach]

Seems like a question for the manufacturer, not for a collection of random strangers on the internet. I'll say yes you can, if you'll post the videos of the results. Going from less than 2 minutes of excess energy input to 10 minutes of excess energy input seems like a good way of making interesting things happen.

 

[racookpe1978]

Electric power produced goes up by the cube of wind speed.
Forces and vibrations on the entire unit (blades, bearing, housing, shafts, and safety cutouts (locks)) go up as well.
Sure, you will get a little bit more power out, for longer periods of time.... until it fails.
Your windmill will fail earlier because it was NOT designed for that extra force.

 

[tmn81]

thanks a lot for your answer, the turbine is vestas 3mw and this turbine there is no shaft, rotor is connected directly to gearbox(hansen)

 

[FreddyNurk]

What does Vestas say about it?

With the different options and implementation for each of the turbine manufacturers (Vestas, GE, Enercon etc), the only realistic answer to your queries has to come from the OEM. In particular, my understanding is that gearbox coupled units may not handle alterations to the cutin and cutout speed as well as the direct coupled units (like Enercon).

 

[mikekilroy]

funny replies....

you are not trying to go OVER the max speed: it is 25m/sec and you are not asking to change it, so no issue with safety....

nothing to do with fact that the power available goes up by the cube of the wind speed....

nothing to do with how much energy is generated over 2 minutes or 30 minutes....

the issue is one of hysteresis setting, like used in LOTS of processes. Nothing different for your 3mw or 300mw or 3 watt windmill, or 10hp spindle or 200HP spindle.... simple engineering question....

So.

*If you set the hysteresis too small - by setting turn on higher, you will simply loose some energy you COULD HAVE GENERATED; (ie., 20m/sec)

*If you set the hysteresis too high - by setting turn on lower, you will generate more energy, BUT will potentially have more on/off cycles of your electrics/generator that may wear it out sooner - or not. Depends on the actual design.

EDIT: so I have confused myself on your on/off.... you say turn off at 25/msec in either case, so that means you shut down energy generation and I assume limit blade speed to prevent damage at 25m/sec, ok. that appears your max limit. but turn ON time seems to be question. what happens if you turn on too low? why not turn on generation at 10m/sec? typically on/off hysteresis is to prevent toggling of some process too often. why would you be asking to RAISE the turn on from 20 to 23?? Shouldn't you be asking to turn it on LOWER?

But the bottom line is you should be able to adjust the LOWER TURN ON POINT to anything you want without ANY worry of damage to ANYTHING and see how it responds.

Perhaps you should simply google "hysteresis" to understand what it means. You will find that YOUR process is different than others and that YOU ultimately can find the BEST value for your device.

[for reference, I must decide hysteresis almost daily for spindle motors from 1 to 200HP "upto speed" and zero speed signals. I built a 10kw windmill with custom software and had to decide MY best on/off points. this is not rocket science if you just break it down to what the function of hysteresis is. If you want to go to the next level, consider not relying on hysteresis but rather build in a proportional output based on speed so you no longer even require this on/off stuff]

http://www.KilroyWasHere<dot>com

 

[racookpe1978]

No, you are only partially right.

The OP original question was, as you point out, leaving the maximum window speed (turn-off point max) at the same place.
Yes, above 25 mph, the wind turbine is either yawed (rotated) sideways, or the blades feathered. (OP is not clear on that, but it matters during EVERY future cycle.)

So, rising wind case: Wind increases above 25, turbine clicks off, turbine blades are cycled off.

Then the wind gust goes away, wind (current setting) drops to 24 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 23 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 25 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 24 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 22 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 23 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 21 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 24 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 23 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 21 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 27 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 24 mph and goes back up, turbine stays off.

Repeat for the next 32 hours. Every four or five minutes. Or 4 or 5 times a minute for 2 hours.


So, rising wind case, new settings: Wind increases above 25, turbine clicks off, turbine blades are cycled off. No difference.

Then the wind gust goes away, wind (current setting) drops to 24 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 23 mph and goes back up, turbine goes on.
Then the wind gust goes away, wind (current setting) drops to 25 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 24 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 22 mph and goes back up, turbine goes on.
Then the wind gust goes away, wind (current setting) drops to 23 mph and goes back up, turbine goes on.
Then the wind gust goes away, wind (current setting) drops to 21 mph and goes back up, turbine goes on.
Then the wind gust goes away, wind (current setting) drops to 24 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 23 mph and goes back up, turbine goes on.
Then the wind gust goes away, wind (current setting) drops to 21 mph and goes back up, turbine goes on.
Then the wind gust goes away, wind (current setting) drops to 27 mph and goes back up, turbine stays off.
Then the wind gust goes away, wind (current setting) drops to 24 mph and goes back up, turbine stays off.

Repeat for the next 32 hours. Every four or five minutes. Or 4 or 5 times a minute for 2 hours.

it is that extra cycling in the previous "dead zone" that the turbine designers are trying to eliminate by requiring a longer period of lower speeds when the turbine is being hit with gusty winds between the trip point point and the reset point.

 

[davidbeach]

I don't think you're getting it at all. The cutout isn't exactly at 25 m/s (different from 25 mph, more like 56 mph), it is some time/speed value above that given the exponential weighting of the speed. So, assuming that it is designed to trip after 100 seconds of 25+ m/s wind and say 10 seconds of 28 m/s wind and 1 second of 31 m/s wind. The controller is filling in a speed time curve and when it's full the turbine is shut down. What the OP is asking is what happens if the area under the curve is increased by a factor of 6. The turbine/generator/tower/etc. then needs to absorb six times as much "above maximum continuous" energy as before, for every overspeed shutdown. That's why it would get really interesting if he were to do that. Extending the time to cut-in reduces the amount of cycling, but could leave you out of the money more of the time at near maximum wind.

 

[racookpe1978]

True. He does get more power. We agree.

And, if his turbine manufacturer finds out he has changed the settings, he should lose his warranty. Immediately.
Then again, these things are usually only good for 7 years service ...