Automatic Wind Turbine Shutdown

[Dan Lenox]

All,

This past fall was a windy one out here in WV. One night we had a huge gust of wind that shook the house and caused me to shut down the turbine.

The next day when looking over my log files the turbine was putting out - well lets just say - well over 5kw... Ok I almost maxed out the inverter at 7540 watts. The log files show that over about 15 seconds the battery voltage went from 54.5v to 67.7v a pretty fast increase, so must have been a huge gust of wind.

So needless to say I live in a bit of a violent place as far as wind goes, as the forecast only called for 17mph winds, and we experienced about 50mph.

My (somewhat minimal 220ah) battery bank and diversion controller could not keep the turbine output in check under this extreme condition.

What I realized is that I wanted/needed an electronic device to automatically shutdown the turbine once the battery level got up to a preset level (> diversion controller)>

A number of discussions ensued (original thread @ http://www.fieldlines.com/story/2009/1/1/162539/5809) and Glen Hurd stepped forward to help out.

Glen as many of you know had previously designed a very small diversion controller for small wind turbines (<400watts). His circuit was pretty close to my needs and we laid out the parameters for the new circuit:


this is not meant to trigger a dump load but to shut down the turbine!
have power light
have status light showing state
for simplicity sake, lets say it drives a 12vdc solenoid/relay/contactor/SSR/whatever so limited to 20amps or less. I already have a 110v 3-phase contactor in place.
means to make it automatic/manual reset, if manual provide for external spst switch
response time < .25 sec once desired trigger voltage is achieved triggered at 'tuneable' voltage
not everybody is 12/24 volts please! work within 48v system, and in my system max of 60v for trigger
I don't care if kit or pre-assembled
cost should be less than C40


The circuit works by monitoring the battery voltage, when it reaches a specific voltage the circuit energizes a solid state relay (SSR) which in turn switches on an electrical relay, which in turn engages my contactor switch. In addition once triggered it requires (optionally) a manual reset to re-engage the turbine. This manual reset is optional but I wanted it for heavy gusty days, my belief is that if it triggered in the first place then something must be wrong.....

Currently I have my TS-60 diversion controller set for 57.6v, and the auto-shutdown set for 59.0v. So if the diversion controller fails or a very heavy wind event happens this device should automatically shut down the wind turbine for me.
Glen sells this circuit and his 'standard' diversion controller as low cost kits on his website (http://ghurd.info/).

Here is a picture of Glens board plus an addition to mount extra parts onto:
601

Here is the layout of the parts in the box:
602

And here is the device in service:
603

The relay was too tall to mount inside the box, so it is offset mounted on the top/back side of the box.

On the box is green led showing circuit is powered, yellow (not lit) showing circuit is triggered, a switch to stop the turbine, a reset switch (for when circuit is triggered) and a main AC power switch.

A big thanks to Glen! And hopefully before too long he will add this circuit to his list of kits that he sells at http://ghurd.info/

Dan Lenox

[Rob Beckers]

Looks cool Dan! The joys of living on a mountain top... Though it is hard to beat those views you have (or the wind energy)!

I think you're on to something, in that it's hard to protect wind turbines from damage due to high winds. My feeling is that it may be a dominant cause of demise for small wind turbines; many don't furl reliably or early enough, or will still speed up while furled. So your turbine will not restart once it's shut down, regardless of wind speed? You have a good alternator! Many will not stay stopped if the wind picks up, or won't stop at all in high winds. At least not by shorting out the alternator.

-RoB-

[Dan Lenox]

Rob,

That's right my wind turbine will not restart until I press the reset switch, the relay/contactor will keep the stator shorted. This reset was an optional feature that I spec'ed out in my requirements.

Glen put in the manual reset because we here can get extreme winds, and I just did not want to see the turbine speed up, shut down, speed up again, shut down - repeatedly, you get the picture. My thinking was that if we got hit with one huge gust then certainly more would follow. This way if I am not physically here it stays in shutdown mode until reset.

Correct, it does not absolutely stop rotating - even while shorted, but even in a 50mph wind it turns at only about 20rpm, and more importantly it's not making power...

This device will help if my dump load or diversion controller fail, kinda like a backup for the backup. But as we all know electronics can and do fail.

This is a nice safeguard and all for just about $50 to boot! At that price it is really almost a no-brainer. Anyone interested in it should contact Glen Hurd directly as he sells the kits (email in above posting).

Dan

[Cor van Houtum]

Hello Dan

Look at my tread
http://www.greenpowertalk.org/showthread.php?t=7032

With the Omron relais you can set the time it will be in activation
this could be a solution

kind regards

Cor

[Stewart Corman]

Dan,
If I read you correctly, when the turbine goes in to overload due to extra high wind gust, you want to bypass the dump load and short out the generator. You are grid tied, but the inverter can't handle the overload in extreme conditions. Aren't you concerned with a mechanical shock to the rotor if you instantly short the leads with a extra heavy duty relay triggered by that SS relay? The blade stresses could be enormous if you are spinning at 350rpm, then suddenly jolt to a shorted condition.

I am thinking a soft stop for two seconds might be worth looking into ... I have a 35KW three phase calrod that might do the trick, before you move into direct short.

BTW, you mentioned manual reset ..why not have a 15 minute delay circuit with a 555IC in single shot mode?? so, it might cycle a few times in an hour or so if really persistent storm

Stew Corman from sunny Endicott

[Dan Lenox]

stew,

nope it never spins that fast, I keep it heavily stalled and am willing to put up with less output to keep rpm's slower - and less maintenance in the long run. as it is 225rpms is pretty much about the max.

Inverter can handle the output it is 6kw and can take about 7kw for short periods. The inverter has a 20second lag period and voltage during that period of time can climb pretty fast with a 17' turbine, Xantrex has a firmware update with a fix, but it probably won't be out for another 4-5 months.

primarily it serves as a backup to my diversion controller, cheap insurance in case of some failure, and I specifically asked for manual reset

dan