Wind Turbine Electronic Yaw Control

Discussion in 'The Projects Forum' started by canaryjohn, Apr 10, 2012.

  1. canaryjohn

    canaryjohn Thread Starter New Member

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    Hi all,

    I am a current owner of a 10kw Wind Turbine, that relies on passive yaw (i.e just the force of the wind to orientate the turbine into the correct position)

    The turbine functions well but in high winds suffers from "buffeting". The manufacturer had fitted a mechanical yaw damper, consisting of some spring loaded nylon pads to provide a resitive force but I feel an electronic solution would be better.

    The turbine output is 3 phase, variable voltage, variable phase, 0 - 400v, which I take to mean a constant current op of 25A (0 - 10kW ??), where op voltage is directly proportional to rotor speed.

    My idea is to have an EM brake that is activated when the turbine reaches a significant rotor speed (I'm basing it on half power so 200v), therefore holding the turbine in its current orientation until the wind speed drops, thus lowering the op voltage and releasing the brake.

    With my basic electronic knowledge and purely using off the shelf parts I have come up with the following solution

    Turbine output will (as well as being attached to the main load, inverters etc to pass to the grid) be put into a 3 phase bridge rectifer, so will now have dcv proportional to rotor speed. DCV then fed into buck DC-DC convertor 200-400vin giving 24vout, which feed em brake. (diagram and links to components attached.

    Am I right in thinking that this would work as described, i.e. until turbine output reaches 200v there will be no op from buck convertor, so em brake will not be applied, then once it reaches >200v, buck will op 24v and activate brake.

    Just to clarify I am no way connected to the turbine manufacturer and am doing this purely to make my turbine more efficient..

    Block Diagram

    Bridge Rectifier

    Buck Convertor

    EM6 EM brake

    Any info would be greatly appreciated. Please talk in basic language.

    Many thanks

    John
  2. strantor

    strantor Well-Known Member

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    I believe the DC/DC convertor will output <24V @ <200V input; it won't be like "off" until >200V is present and then it starts outputting. I could be wrong about that, it's just what I observed with other DC/DC convertor.

    Your rectifier is way overkill. It's rated @ 127A, and your DC/DC only draws .5A. You don't even need to rectify all 3 phases. You could do this with a few cents worth of radioshack diodes.
  3. wayneh

    wayneh AAC Fanatic!

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    Not quite. The EMF goes up directly with the rpm. So with no load, the voltage will go up in proportion too. Current depends on the load. All else equal with a resistive load, current will go up in proportion to voltage. So power (voltage times current) will go up with the square of rpm. Since rpm changes with wind speed, power available goes up with the cube of wind speed.

    Anyway, in my opinion it would make more sense to make a brake that is controlled by rpm. That is, the information you need is rpm, but the power to the brake is applied in a controlled, consistent way and does not rely directly on the turbine output. I'm making a distinction between the information (rpm info from a tach) and the power (to be steadily applied to the braking mechanism). I hope that makes sense.
  4. canaryjohn

    canaryjohn Thread Starter New Member

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    Am I right in thinking though that this will still make the system work ok, as even if the voltage is <24v rather than 0v the EM brake will still no be activated until a >24v is present?

    Yeah I agree the rectifier is way over kill, was just the one I found at the time. When you say I don't need to do all 3 phases, I though I would have to do all all3 to get a true DC level for the turbine output, or would the ACV be exactly the same for all 3 phases of the generator output?

    As load always remains the same, then current as you say current will also increase proportional to rotor speed?


    That was my original plan, but there is no power source present at the turbine head, other than that coming from generator output itself. As I understood it I would need a stable voltage source to provide power to the RPM measuring device, which would mean getting that from the generator output and rectifying and regulating it anyway?


    In general though would the system idea I have come up with work?
    Last edited: Apr 11, 2012
  5. strantor

    strantor Well-Known Member

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    Well,, if I'm right, (which I'm not sure that I am), then you would have more like analog control. Your brake would be weaker below 200V, and weaker and weaker the further below 200V you get.

    Well either way you are going to have some ripple & need some filter caps. Rectifying all 3 phases will just give you less ripple. You can rectify 3 phase just as easy with a few extra cents worth of off the shelf diodes. Here's what's inside your rectifier that you linked to:
    [​IMG]
  6. wayneh

    wayneh AAC Fanatic!

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    If it's a passive resistive load, like a light bulb or heater coil, yes. The voltage, current and power will all go up.
    Yes that's true but the amount of power needed to watch rpm and produce a control signal for the brake is very small. Applying power to the brake will take more power, but even that is very small compared to the turbine output. At the turbine head, do you have room for, say, a 3-inch square printed circuit board? I think that's about all you'd need to have a small power supply and a few components for the control "head". How exactly do you plan to apply power to the brake? In other words, how much juice will you need to apply?
  7. shortbus

    shortbus Senior Member

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    Why not use a "fly-ball' type governor on the turbine shaft? Like is used on a steam engine to regulate speed. This would be a purely mechanical way to keep the turbine speed controlled. The faster the wind speed the harder the braking force, and its adjustable to keep the voltage at a maximum level. http://en.wikipedia.org/wiki/Centrifugal_governor
  8. canaryjohn

    canaryjohn Thread Starter New Member

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    There is the room for a PSU, but where would the PSU receive its power from if not the turbine output. I say this as basically I dont want to have to run a cable back the 300m from where the turbine connects to the mains (our farm shed) back to the turbine.

    The plan was as described to simply in effect take off ssome power driectly from the turbine output, rectify it and the convert it down to a useable voltage that could be then be applied to the em brake. I think the em brake is rated at 30w and at 24v so therefore 1.5A

    Its not the speed of the turbine shaft I am trying to control, its the rotation of the turbine head (i.e the direction is faces in relation tot he wind)

    Also there is no turbine shaft as such as the generator within the turbine isa permanent magnet type and as such is a sealed unit where I have no access.


    Having thought through all the options the only real solution to save running a cable back from the barn to provide a voltage to control the turbine heads yaw is to use the op from the turbine generator, rectify it to DC and then use that voltage to control the brake.

    From the components and general description I have given would this work?
    Last edited: Apr 11, 2012
  9. wayneh

    wayneh AAC Fanatic!

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    I think this is no problem at all. As noted, you could probably just rectify a single phase. If it's easier or more satisfying, just use a full 3-phase rectifier. 30W isn't trivial, so you'll probably need a heat sink for the rectifier. It might need to run at full power for hours at a time. You may then want some filtering and voltage regulation for the control circuit.

    Another thing you need to wrestle with is fusing, and startup conditions. That is, you need to resolve what happens if your electronics fail or aren't working at all times. Blowing a fuse at 30mph winds would let the blades go "free", which is a bad thing?
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