Author Topic: 180 volt 3.2 meter turbine  (Read 21709 times)

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Offline ChrisOlson

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180 volt 3.2 meter turbine
« on: February 12, 2012, 05:52:56 pm »
This is the stator for a new turbine I'm going to experiment with - just got the stator done today:

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This new turbine is a 3.2 meter machine like the last one, with a geared generator.  But I'm using a 12 pole 9 coil three phase neo generator on it.  It will hit 180 open volts @ 450 rpm (blade speed), and it's design max power @ 400 rpm is 160 open/147 loaded @ .47 ohm internal resistance for 27 amps, or 3.9 kW power output @ 91.9% power efficiency at the generator.

It will require a lower gear ratio than my previous ferrite generator, which will improve the drivetrain efficiency by about .6%.

The purpose of this experiment is to see if I can build a CHP turbine.  Run the Classic 150 controller right up against its voltage limit with the blades running at TSR 6.5 so the voltage clipper will be required to come on just to regulate the voltage during normal operation.  Then dump the excess to three phase water heating with the clipper as part of normal operating parameters.

The reason I chose a neo gen for this one is because it's hard to get that sort of efficiency and voltage from a ferrite generator for a turbine this size.  With the neo gen it's easy.  I had to de-rate my ferrite 3.2 meter because it wouldn't furl running at too high of a rotor speed.  With this one I won't need to over-speed it to get the voltage I want from it to be able to do this, and at 30 mph those 3.2 meter blades got 4.1 kW available at the shaft.

Rather than de-tuning it, I want to build one that can run balls out just to see how much you can really get from a 10.5 foot turbine.    :)
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Chris

Offline rossw

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Re: 180 volt 3.2 meter turbine
« Reply #1 on: February 12, 2012, 06:04:23 pm »
Chris - serious question.

If you're building turbines that can run balls-out all day and not explode or catch fire, have you considered doing away with the furling tail and all its attendant complexity, cost and weight, and making downwind units?

For a modest increase in weight/complexity/cost, you could put a disc brake on it to stop it in the event of a major blow.

Just seems to me that with "tough as nails" turbine assemblies and control gear, and something to *DO* with all the power, the tail is just unnecessary clutter and one more thing to fail?

Offline Wolvenar

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Re: 180 volt 3.2 meter turbine
« Reply #2 on: February 12, 2012, 06:43:21 pm »
My last long term wind genny I had in the air was a small 6 footer zubbly style motor conversion that had no furling, and ran out full speed. It did end up failing in a spectacular fashion, but it took many unbelievable winds in stride. If I remember right we were topping 120 mph gusts in a massive storm to take it out. The genny was an approx 600 watt in strong winds, it was made from a motor that was originally a 1/2hp motor rewound.

When outside you used to hear that thing in high winds making sounds that would scare just about anyone, but it took it in stride.
With some integration of a 1:1transmission and a heavier shaft, the genny would have survived  the blade coming apart, and it would likely still be out there today. The transmission loss would have been negligible as far as losses I would think given I would rather it still been alive making some power.
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Offline ChrisOlson

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Re: 180 volt 3.2 meter turbine
« Reply #3 on: February 12, 2012, 07:31:28 pm »
If you're building turbines that can run balls-out all day and not explode or catch fire, have you considered doing away with the furling tail and all its attendant complexity, cost and weight, and making downwind units?

I have considered eliminating it as a furling tail and just place the turbine inline with the yaw as an upwind unit.

I think I'm to the point where I'm reasonably comfortable with controlling the turbine with electronics.  Using a very robust generator with gearing provides greatly enhanced control over rotor speed even in very high winds.  After I test and tune this one, if it works as expected, it will not need a furling tail and still be able to bring the turbine under control and stop it at 70 mph wind speed, with just the generator, with no damage to it.

When you can use PWM to drive your clipper, using a grossly oversized three-phase clipper load, you can bring a speeding turbine under control very gently with the PWM.  And at the same time, match shaft power to the clipper load using the PWM at virtually any speed.

Once I achieve that, you'd better believe that furling tail will be gone and replaced with an emergency parking brake for wind speeds over 70 mph.
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Chris

Offline ChrisOlson

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Re: 180 volt 3.2 meter turbine
« Reply #4 on: February 12, 2012, 08:40:45 pm »
With some integration of a 1:1transmission and a heavier shaft, the genny would have survived  the blade coming apart, and it would likely still be out there today. The transmission loss would have been negligible as far as losses I would think given I would rather it still been alive making some power.

Wolv,

The transmissions I build are 95.5% efficient at cut-in and 94.8% efficient at 3.3 kW input power.  What that equates to, basically, is 8 watts loss at cut-in speed, mostly due to viscous drag from oil on the chain.  At 3.3 kW input it equates to 172 watts loss in the drivetrain, and about half of that is due to the extra set of bearings you have to run when you have two shafts as opposed to one.

On a smaller rotor where you would only have say 1 kW input power, then the efficiency is right at 95%, meaning you'll lose 50 watts in the drive.

There is no "free lunch" with gearing - you have to trade torque for speed to make gains in gen efficiency to get it to work out to a positive net gain.  And I think the smaller the rotor, the harder it is to justify using gearing on it.

On these very high voltage turbines I'm building now, it's a hands-down no-brainer to use gearing.  There is no way to build generators that put out 180 volts at only .47 ohm resistance @ 400 rpm without gearing, and still get the coils to fit in the stator.
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Chris

Offline Watt

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Re: 180 volt 3.2 meter turbine
« Reply #5 on: February 12, 2012, 08:59:12 pm »
With some integration of a 1:1transmission and a heavier shaft, the genny would have survived  the blade coming apart, and it would likely still be out there today. The transmission loss would have been negligible as far as losses I would think given I would rather it still been alive making some power.

Wolv,

The transmissions I build are 95.5% efficient at cut-in and 94.8% efficient at 3.3 kW input power.  What that equates to, basically, is 8 watts loss at cut-in speed, mostly due to viscous drag from oil on the chain.  At 3.3 kW input it equates to 172 watts loss in the drivetrain, and about half of that is due to the extra set of bearings you have to run when you have two shafts as opposed to one.

On a smaller rotor where you would only have say 1 kW input power, then the efficiency is right at 95%, meaning you'll lose 50 watts in the drive.

There is no "free lunch" with gearing - you have to trade torque for speed to make gains in gen efficiency to get it to work out to a positive net gain.  And I think the smaller the rotor, the harder it is to justify using gearing on it.

On these very high voltage turbines I'm building now, it's a hands-down no-brainer to use gearing.  There is no way to build generators that put out 180 volts at only .47 ohm resistance @ 400 rpm without gearing, and still get the coils to fit in the stator.
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Chris

What size are the rotors for this one?
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Offline ChrisOlson

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Re: 180 volt 3.2 meter turbine
« Reply #6 on: February 12, 2012, 09:21:43 pm »
They are 255 mm with 2 x 1 x .5 N42's

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This is the same generator as the 12G turbine has, except running at 1,300 rpm on this one, and five more turns of wire in the stator.  This one has .343 gears in it.
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Chris


Offline Wolvenar

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Re: 180 volt 3.2 meter turbine
« Reply #7 on: February 13, 2012, 12:05:49 am »
Notice 1:1 ratio.
Maybe not so much a transmission, as a larger shaft in bearings, with a rubber or padded joiner connecting the two in a strait line.
This would be because the motor shaft was extremely lightweight for the job it was doing.
Any which way I like the way you setup your bearings, and an adaptation of this would have saved the alternator. I am not sure if its because I have the access to mills, lathes etc, but I don't find that it would be to incredibly hard to replicate a design like Chris has. I am sure there are things I do not know about it, but with work, and maybe a couple tries I am confident I could pull it off. I'm reasonably sure there are a few here also that could if they set out to do it.
 Not to say Chris's design isn't something set apart from the ordinary.
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Offline rossw

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Re: 180 volt 3.2 meter turbine
« Reply #8 on: February 13, 2012, 12:08:35 am »
Not to saying Chris's design is not something apart from the ordinary.

I've read that a bunch of times, and too many double-negatives for me to comprehend!

Offline Wolvenar

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Re: 180 volt 3.2 meter turbine
« Reply #9 on: February 13, 2012, 02:08:10 am »
yeah,. I do that a lot. seems that growing up in a multiple language  family screwed me up.
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Just to abuse what I make. (and run this site)

Offline ChrisOlson

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Re: 180 volt 3.2 meter turbine
« Reply #10 on: February 13, 2012, 06:12:47 pm »
Well, on all my other geared turbines I built weldment gearcases out of sheet steel like this:

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I found a piece of 3 x 6 x 1/4" wall rectangular tubing and cut off 10" of it.  The big cog barely fits in it:

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Bore a couple holes thru it for shafts, weld a bottom on it, weld a flange to the top for a cover, and I got a gearcase.  It'll work mint and save a lot of welding.
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Chris

Offline ChrisOlson

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Re: 180 volt 3.2 meter turbine
« Reply #11 on: February 19, 2012, 09:02:34 pm »

Offline oztules

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Re: 180 volt 3.2 meter turbine
« Reply #12 on: February 19, 2012, 09:57:09 pm »
That will be an exciting machine to be near .... 700 rpm is getting very exciting

No matter what else I may say, you do nice work. I like the box section for the g/box.

Will it float between buck to heat, or buck and heat simultaneously?


..................oztules
Flinders Island...... Australia

Offline ChrisOlson

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Re: 180 volt 3.2 meter turbine
« Reply #13 on: February 20, 2012, 04:22:03 pm »
Oz, I will program the power curve in the controller to let it run the turbine at 475 rpm @ 147 volts, or about TSR 6 @ 30 mph.  The controller begins to unload the turbine from the DC load if one of two things happens:
  • The amp limit you set in the controller is reached (I have this set at 84 amps presently).
  • Either absorb or float stages of charging are reached.
When the controller unloads the turbine from the DC load due to one of the above the Aux 2 output of the controller switches the turbine over to the three-phase load with PWM driving a SSR.  It regulates the voltage at the 147 volts.  If it can't hold it at 147 due to excess turbine output (wind speed in excess of 30 mph) it will go over the controller's input voltage limit of 150 volts.  The controller then goes into what is called "HyperVOC".  In HyperVOC the controller stops charging batteries and the load is totally switched over to three-phase.

When the input voltage again drops below 150 the controller starts charging batteries again.

At 40 mph wind speed the turbine should not actually exceed 500 rpm, as the harder it tries to turn as the wind picks up, the load of the three-phase water heating increases faster than shaft power and stalls the rotor.  I'm setting it up to furl between 35-40 mph with the rotor running on the bottom end of it's useful power curve (~ TSR 5).

If I would let it scream to 700 rpm by not having a heavy duty enough three-phase heating load, it would indeed be an interesting machine.

The first turbine taught me about how the controller works and I found you can't blow it up by running it over voltage or over amping it.  boB and Robin have been in the business long enough to know better that to let that happen.  This one is being designed to be able to take better advantage of the turbine's ability to heat water with high-voltage three-phase power, and the controller's ability to switch it back and forth and "blend" both the DC and AC loads as needed to control the turbine's speed.

Many times, what happens is that with both solar and wind the bank will reach float by noon and then the turbine is heating water all afternoon.  The solar controllers regulate the bank at 26.5 volts and the bank and inverter loads can't even come close to using full turbine output.  So rather than running the heater elements with inverter power like I do with my other turbines, why not heat water direct with the three-phase power off the turbine?  You can heat a lot of damn water with 3 kW all afternoon - probably more than we can use in a day, and we got two 55 gallon water heaters to store it.  That's why I'm doing this one this way.

I got one element controlled by the thermostat and that one runs off inverter power.  That one insures that we always have at least 25 gallons of 125 degree water in the primary water heater.  I got the other three elements (bottom in the primary heater and both in the pre-heater) wired delta for the clipper load.
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Chris




Offline oztules

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Re: 180 volt 3.2 meter turbine
« Reply #14 on: February 20, 2012, 05:07:59 pm »
Sounds like a plan.

When I played with resistive loads, I found that the thing runs away, and as it passed 5kw or more... I wanted to as well.
My problem was that the furling didn't behave as I expected it to..... and it just didn't furl. I don't know how far it went past 5kw, as the amp gauge was pinned to the end, and the voltage was heading past 150 from memory.

I think DaveB mentioned a change in furling behaviour..... but that was after I found out the exciting way. Direct shorts at over 5kw didn't bother the mill... (yet another failed experiment)  but it sure bothered me.. ;D

Will be interested in the eventual outcome.


...............oztules.

What made it more exciting is that  it was on a 3 meter pole/tower, and a bit close for comfort.... There is a write up somewhere of one of the times. If you saw the write up my chainsaw blades, you may note the myriads of knots in the crummy pine.... and that introduced more than a bit of doubt  as well.
Flinders Island...... Australia