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gpalterpower
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Posted: 03 September 2017 at 8:54am | IP Logged Quote gpalterpower

Thanks guys,
I just needed some sort of uF value to begin with. As luck has it, I was going thru some old boxes today and came across 6 caps with a rating of 450v /470uF. Think the'll do the trick so Im gonna give them a go and see if there is any increase in output, but there's just one thing that puzzles me.

I noticed in the "Electronic projects and info" section, where "Gordons Cap Mod" schematic is wired exactly the same as the one in the
Quote:
f n p gridtie windturbine, triple stator
thread . Just curious why, there was only a small improvement in output then , but Dave who is doing great work on this subject, is extracting unprecedented power output. Is it because of the uF rating or the type of caps used? Id appreciate any thoughts on this.

Marcus

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DaveP68
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Posted: 03 September 2017 at 10:44am | IP Logged Quote DaveP68

Hi Marcus

Yes that is where I copied that circuit from. But it's not a Capacitor Multiplier, it's in fact exactly how I connect the capacitors to the stator for power factor correction.

DC 470 uF caps connected as series pairs will make 235 uF AC capacitors and will be close enough in value to make a big difference. Remember your main drive stator must be wired 12x 1c Delta to get any good results (lots of current) at 24 VDC.

gpalterpower wrote:
Just curious why, there was only a small improvement in output then , but Dave who is doing great work on this subject, is extracting unprecedented power output. Is it because of the uF rating or the type of caps used?

Marcus


Have no in depth knowledge of what was done 8-9 years ago with the capacitor doubler testing etc.

The one thing I do understand is the capacitor doubler does have a wider operating RPM range, but this feature in my opinion is a miss guided view point.

As most on here will already know wind is cubed law, so as the wind speed doubles the power extracted is 8 times greater. This works to your advantage with power factor correction as when it approaches it's peak output the power output climbs very steeply.

More results to follow as I haven't got the maximum output from power factor correction capacitors yet.

David
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Warpspeed
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Posted: 03 September 2017 at 7:09pm | IP Logged Quote Warpspeed

I suppose it depends on what you are trying to achieve.

While I can see that its possible to extract much more power at higher rpm by tuning with (resonant) power factor correction, that is not going to help much with cut in at very low wind speeds.

If you truly live in a location where there are strong constant steady winds, higher power output has to be a good thing. But that is only going to occur where there is more shaft torque available than the alternator can use. So loading it up more electrically can produce more electrical power, but only if there is excess shaft power available to do it with.

At the other end of the scale, where winds are marginal to non existent much of the time, a greatly lowered cut in speed will probably gain you far more than tuning it for higher power output during high winds.

So very much depends on the blade/alternator combination you have, and the prevailing wind pattern.

I can see that a capacitor voltage multiplier would be just the thing for reduced cut in speed in light or variable winds.

For a coastal location with strong steady prevailing high wind, if the system is overpowered with wind, then this power factor correction scheme might offer a very worthwhile improvement.

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DaveP68
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Posted: 03 September 2017 at 8:39pm | IP Logged Quote DaveP68

Tony you overlooked what is on the first page of this topic.

DaveP68 wrote:
Hi Marcus

A 24 VDC system might work with a Dual 36 pole copper staggered stator setup.

The first stator (cut in) would be a 1x 6p Delta with 27-28 Volts at 80 RPM. Then the other half of this first stator is wired as 2x 3p Delta with cut in around 160 RPM. No power factor correction capacitors are required on this stator.

The main drive stator is set up as a 12x 1p Delta with the power factor correction capacitor sized at about 300 uf AC in Delta mode as explained in my other topic.

The total current could be as high as 45 Amps, so run some fat cables!

Peak power of 1200+ W could be reached at 500 RPM or even before that.

Think it's worth a try.

David


If you also read up on my "Cap Doublers vs Power Factor Correction" topic it states there's a 33 % power loss when using a Cap Doubler vs a standard stator or with PFC caps.

The one big advantage of the F&P stator is they can be rewired into many different modes of operation star/delta, staggered setup etc to suit different battery voltages system etc.

Taking all this into consideration the Power Factor Correction will work as I've described in what ever wind conditions. They only cut in to give the extra power at a higher RPM where there is going to be the sufficient shaft torque available.

I just don't see a problem with trying it out on a wind turbine to prove the operation of Power Factor Correction.

Hope it works out for Marcus.

The Single stator operation with Power Factor Correction can only be done with the wide voltage operating MPPT inverter (40 - 540 VDC) that Fred is about to install on his new Wind Turbine.

David
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