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Warpspeed
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Posted: 26 June 2018 at 3:35pm | IP Logged Quote Warpspeed

If the home position coincides with the usual prevailing wind direction, the reset action should get a reasonably good workout.

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Warpspeed
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Posted: 27 June 2018 at 11:08am | IP Logged Quote Warpspeed

Another thought about the loss or corruption of the direction sensing.

You can get good quality potentiometers that are designed for continuous motion (without rapidly wearing out) and are often used for position indicating with mechanical servo systems. These potentiometers are also designed to have no mechanical end stops.

There would be all kinds of difficulties using one of these for primary position indication, because of the necessary break in the track at one point, and the sudden very violent 360 degree jump in readout that creates.

But it could be used for verifying the primary incremental counter at any time, and you could write into software to just ignore it whenever it gets dangerously close to either end of its resistive track, and only carry out a correction when its in a safe area of its angular travel.

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Madness
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Posted: 27 June 2018 at 12:00pm | IP Logged Quote Madness

You could make a version of a rotary encoder with 2 micro switches and 2 semicircle pieces of pipe offset by 90 degrees. This would allow a microcontroller to know the direction and number of turns from home position.

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Posted: 27 June 2018 at 7:17pm | IP Logged Quote Tinker

Warpspeed wrote:
Another thought about the loss or corruption of the direction sensing.

You can get good quality potentiometers that are designed for continuous motion (without rapidly wearing out) and are often used for position indicating with mechanical servo systems. These potentiometers are also designed to have no mechanical end stops.

There would be all kinds of difficulties using one of these for primary position indication, because of the necessary break in the track at one point, and the sudden very violent 360 degree jump in readout that creates.



I have used one of these servo pots for many years on my windvane (direction indication).
A cascaded LM3914 chip decoded the varying voltage output to 16 direction steps, driving LED's arranged in a circle.
I had set the 0 pint to the least common wind direction here - North.

Unfortunately the pot track wears out after 10 years or so at the most common wind direction, SW here.

There is an optical rotary encoder (I have one but not yet installed) which puts out two pulse trains offset by 90 degrees (if I recall correctly) and from that the direction could be computed.
However, this would require more than the two existing wires going up to my windvane which is why it has not yet replaced the worn out servo pot.


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Boppa
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Posted: 28 June 2018 at 10:08am | IP Logged Quote Boppa

I had an old exmil setup for many years that had two loops, one driven by a circuit, the other hooked up to a meter, depending on the mast rotation, it varies the output on the meter (variably coupled transformer)
was great until I moved and lost the box it was in
:-(
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BarkyJ
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Posted: 15 July 2018 at 7:21pm | IP Logged Quote BarkyJ

Hey All

Bit of an update.

Got the mast pole, cut it in half, added a hinge arrangement and a lock. Fabricated the motor mount, and the mount for the drive cog.

Over the weekend we got the mast pole base concreted, pole is removable, hinged 2.5m above the ground, and then about 3.2m above the hinge. Pole goes into the ground just under a meter. It's a 76mm OD medium wall black pipe, about 3.6mm thick or so.
Got the guy wire supports in the ground.
Installed the 3 12mm eyelets into the pole for the guy wires.
Devised the winch system to raise and lower the mast today, that works well.
Measured all the lengths for the wire rope for the supports after getting the mast fully raised up, so will get those bits ordered tomorrow. Will be using 6mm galv wire rope, turnbuckles, wire gips, etc. Should work out well.

All going pretty well really.

Been building the more final controller, which is taking shape, few more bits to add to it plus more testing to do, more code to write, but going well.

Got the wind vein and speed sensor installed on top of the control shed, a stone throw from the windmill itself, along with 20W of solar to keep the controller's batteries charged during the day.

Few progress pictures.







Next step is to get the blades I have made, mounted on the hub, balanced, then bolted to the generator. Then the generator connected to the controller for some more testing, then attached to the mast, motor mounted, more testing, etc etc, then we might be somewhere near ready to do some initial controlled tests. Still got a few 'what if' situations to work through and how to handle them, but they are all part of the fun of building one of these things.

Enjoying every minute of it, what a great project.

Cheers
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Boppa
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Posted: 15 July 2018 at 7:32pm | IP Logged Quote Boppa

Only issue I can see that might cause problems is having the sensors on the shed- you have a bit of a hill behind you by the look and surrounding houses etc, the wind at the shed level might not be anything like the wind at the genny- I would think having the sensors near the top of the mast might be less of an issue
Been ages since I played with wind gennys, but anything nearby (trees/houses/hills etc) can cause turbulent air flow around them

I know a genny system on a yacht to provide power when moored, they had one at the top of the mast, one at the bow and one at the stern, all three often ran at different speeds and different directions- sometimes facing opposite each other- all this with a length of 45 ft between them max and a height difference of about 80ft...
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BarkyJ
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Posted: 16 July 2018 at 7:10am | IP Logged Quote BarkyJ

Hey Boppa

Yep, a valid concern.
Only had it up a few days, and the wind direction does seem stable as either a Westerly or an Easterly, but the wind has been so light. It doesn't flutter around much at all, so I think we are OK.

On the top of the hill behind us is a school field, and the wind often comes off the field and then down past us, as it flows down to the road below. The windmill itself should cop all this as its basically level with the field, but yes its a question as to whether the sensors will pick this up accurately, or show something different.

So far it seems to be OK though, but its something I am monitoring to make sure its valid data.

I did think of putting sensors on the mast, but I didn't want the windmill itself to affect the sensors, so opted for close by instead.
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Posted: 18 July 2018 at 4:42pm | IP Logged Quote BarkyJ

Boppa - you were quite correct, the shed turned out to be a flop in terms of location for the sensors. So today I rebuilt the mast and put it up on the house roof, which clears the hill now. And now I have a northerly and its nice and stable.
Got it up just before dark.



Got a box of presents today too, so got those installed (I should have been working...), but now the windmill is secured with 6mm steel cables.

Lifting plank is still in the pictures, that will be lowered down and removed obviously.







Pictures likely come out too small on the forum, hopefully they are still visible.

Making progress :)
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Posted: 18 July 2018 at 4:45pm | IP Logged Quote BarkyJ

So the hill where Dad is standing in the last picture is about level with the rope eyes securing the mast. So there is about 1.6m above those to the top of the pole, so 100mm or so to the centre of the blades, and then 1.4m to the top of the tip of the blades. So it should work out well. Quite a difference in air when standing up on the hill, compared to down by the shed.

Time now to focus on the Turret again, get that rebuilt after painting it, get it installed with the motor, and then onto the blades.... gulp.
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Warpspeed
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Posted: 18 July 2018 at 5:02pm | IP Logged Quote Warpspeed

Its certainly a fairly difficult site, but it may not be all that bad.
The wind coming over from the sports ground may be a bit turbulent, but if there is enough wind, it should work fine.
In the other direction, steeply rising ground is actually quite good.

I have never built a wind turbine system myself, and live in the yuppie suburbs so never will.
But a long time ago I worked for the Victorian Solar Energy Council, and was part of the team responsible for planning and monitoring some government funded wind turbine sites, so this project is of great interest.

Boppa is spot on about monitoring at a position as nearly identical to the final turbine position as possible

Edited by Warpspeed on 18 July 2018 at 5:08pm


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Madness
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Posted: 18 July 2018 at 5:22pm | IP Logged Quote Madness

Turbulence will cause you lots of grief and the harder the wind blows the more turbulent it will be.

I struggled for a few years with a 1500W Dunlite up a 24 metre tower, strong turbulent wind would cause it to turn 360 degrees quite often. AFAIK you need to get at least 10 metres above anything nearby. I had a steep slope to the east and the blowing up it amongst trees was the worst even though the generator was at least 15M above them in altitude. A paper streamer on the end of a very long pole is one way to check turbulence.


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