MOTORIZED YAW CONTROLLER

[Usman]

I was wondering if any one could feedback on designing an electrical/motorized yaw controller (homebrew) that could position the rotor into wind as the wind direction changes. Perhaps another similar concept is used else where?

The mechanical part is easy, a worm gear coupled to a dc motor that can receive  signal to turn 'left' or 'right' upon receiving a signal from the controller. I am not sure, but seems like that would need proper engineering design. Perhaps would need designing a circuit or programming a micro-processor or PLC that receives a signal from a "wind vane sensor".

Any one has any experience or have an idea of doing that in a simpler but reliable way?

Thanks.

[Norm]

As soon as you start thinking motorized, you're

going away from simple and reliable.

The sensor would be quit simple....the wind

changes direction it operates one of two switches

either the right or left.

              ( :>) Norm.

[adelaide]

is more complicated but if u did do u may be able to have a second set of swiches that are in fureld position actvated by hi wind flap to swich  , complicated and prob less reliable than tradishonal but is posable

[adelaide]

1  advantag of that system  would be u may be able to get away with a big 2 blade prop cos it wouldent yaw fast and get the deth wobles

[pepa]

this drawing was an idea i had to control the weight of the tail. it would allow you to set furling to any wind speed that you choose, are use as a safe method of shutting the mill down in high winds. pepa.

[finnsawyer]

I suppose one could use the worm - gear arrangement from something like a wrecker winch.  That could be driven by an orbital hydraulic motor, the direction of which could be controlled by relays energized by the direction of the weather vane.  One might have problems with the unit tending to "hunt".  While I haven't built such a unit I did adapt a wrecker winch to my bulldozer and powered that by an orbital hydraulic motor off of the twenty gallon per minute hydraulic pump of the dozer.  The winch is pretty slow, but the speed does seem to be in the ball park for what you want.  Anyway, you could slow it down further by using a lower flow rate.    

[alancorey]

I've been poking through the Danish windpower.org guided tour at http://www.windpower.org/en/tour/wtrb/yaw.htm as I have time, and it says that "Almost all horizontal axis wind turbines use forced yawing".  I guess they mean big commercial ones.  In the diagrams at http://www.windpower.org/en/tour/wtrb/comp/index.htm you can see the weathervane and anemometer hanging out the back.  These things are big enough that you climb up and walk around inside (144 feet diameter, 600 KW).

The Danish government is taking wind power very seriously and intends that over 50% of the country's electricity should come from wind by 2030.

I don't know how many of their ideas can be economically downscaled to DIY mills, but it's something to gather ideas from.  I would think something like a car flywheel with a starter motor gear might work.  Or maybe the approach of cutting a slot inside a circle and using bicycle/motorcycle chain glued into it as a gear which I've seen here if you need to keep the weight down.  They also use braking on the yawing, a little bit like antenna rotors.  I assume the brake is on by default and they energize it to turn it off when yawing.  A good survival approach in high winds if you can yaw out of the wind and sit parked.  And you can have a turns counter that keeps track of how many turns are in your wires coming down the tower and unwinds them when it needs to.  Of course these big machines are all variable pitch as well, controlled by computers.

I think eventually we'll reach the point where all this stuff is mass-produced by a few big companies and you can pop into your local store to pick up a new blade or gear when you need one.  Right now with everything being made individually every part is unique, and as expensive as any prototype or R&D part.  Ask yourself if you'd be able to afford a car if Henry Ford hadn't come along and mass-produced parts.  There'll still be room for modifications.

So yes, you'd probably need a servo or stepper motor arrangement, controlled by at least a PIC chip, and some programming.  For a big mill it might make sense, but am I going to add it to my 4-footers?  Probably not.

  Alan

[SamoaPower]

Congratulations on thinking outside the box. I agree that controlled yaw has numerous advantages and is the way to go. For more discussion see the following:

http://www.fieldlines.com/story/2006/6/26/12214/2424

For the past few months I've been playing with a small downwind machine mounted on an antenna rotator.

I've only been manually positioning it with the original rotator controller to determine output sensitivity to wind offsets. Generally, I find little difference in output with offsets up to 30 degrees or so.

The 16' machine under construction will use the same system but with a more powerful rotator.

Initially, the controller will be analog and when the control parameters are determined, it will be translated to a microcontroller. It's easier and quicker to make changes with a soldering iron than to reprogram.

As I see it at the moment, necessary controller functions are:

Integration of wind direction data to obtain an average, possibly with adjustable time constant.

Controlled acceleration and deceleration of yaw speed. Sudden starts and stops are hard on machinery.

Integrated wind speed/power output sensed furling, where a 90 degree offset is applied to the wind direction data.

Optional power output control of furling offset.

Failure mode detection, alarm and shutdown.

Wind speed and direction data would normally come from the site anemometer but an interesting alternative arises if a downwind configuration is used. A probe can be mounted on the machine extending upwind with a relative wind direction sensing vane on the end. Now, the controller only has to seek a null when the vane points upwind to determine correct yaw position. I'll probably try this.

I hope you pursue controlled yaw since I firmly believe it's worthwhile.

[Usman]

Hi Samoapower,

Thank you for your feedback comments and encouragement to pursue this further ahead.

Electronic yaw controlled is indeed one of the most interesting features you can add onto any wind turbine. It offers many benefits, the most mentionable one if the controllability at any wins speed and 90 degree parking at any wind speed you like. Infact, the monster wind turbines would exist today without a control over their yawing ability.

Anyhow, I ma sure you must have had reached some stage within your development for an electronic yaw controller. My imagination would be a wind vane sensor sending a signal to a PIC Controller and the PIC instructing a set of relays to turn a DC motor clockwise or anticlockwise. It could even be achieved by a micro-PLC e.g. Schneider Zelios. But would be simpler and a lot cheaper with a PIC or another micro-controller.

An anemometer could be added, which would help in not activating the yaw motor (wasting useful amps) below a certain preset wind speed. It would also come into action when the wind seed is high and we prefer the wind turbine to furl out of wind, at any pre-specified wind speed. Also, not to ignore the fact that if you have a motorized yaw controlled, you may force over-twsiting the cabled causing major damage. A limit switch could be used to disconnect the whole electronic yaw mechanism from the mains. Also, manual LEFT & RIGHT switches would be needed to untwist the cables. The whole thing is just simple in today's world of electronics and automation.

I know all the above because I was involved in a project to add EYC to a small 48V/3KW Battery charging wind turbine. I got the whole thing designed and sent to me by a Danish Controls company but I was not able to attend to it because of personal reasons and when I returned to the project three months later, the guy who was in charge of the project had resigned, leaving me unable to do anything with the Schneider TWIDO PLC.

I learnt a lesson, and now trying to find way of getting it done locally and in the simplest way possible. PIC seems to show up as the most feasible solution.

However, I haven't started anything yet and still looking for suggestions or a compete solution. I would imagine it wouldn't cost more than $250-$300 if it was done using a PIC and I am prepared to invest that money if someone can offer deliver a solution, along with the know how. I am an electromechanical guy and controls is my weakest point.

Please suggest to me what may be the right solution for me, and if you can or recommend someone supply me with a complete electronic unit.

Thanks, Usman.  

[3rd Charm]

If you can find an old  stanley garge door opener, it has the gear reduction and probably all the electronics and sensors and switches you may need.

 I found one just the other day in fact.(it works! It just had a small crack in the electronics board, a little solder cured it) Alternatively, you could just find a small dc reduction motor, and use a  simular switching setup as the stanely garage door opener, and use it to control  the reduction motor. You should be able to find the schematics of it online somewhere which may help you develop a system.