Author Topic: Power factor correction capacitors used on wind turbine PMA's  (Read 1696 times)

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XeonPony

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« Last Edit: October 31, 2017, 07:02:49 AM by XeonPony »
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SparWeb

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Re: Power factor correction capacitors used on wind turbine PMA's
« Reply #28 on: October 31, 2017, 04:37:57 PM »
Dave,
I think you could be underestimating some of your efficiency numbers.

Do yourself a favor and check that the power drill is actually delivering the mechanical power that you think it is.  Remember, efficiency cuts all machines, so the efficiency of your power drill is dependent on its speed, gearing, and the voltage you get out of the wall.  Measuring the drill's power consumption is a start, and relatively easy to get an accurate number.  If the drill uses 1200W of electric power, you can be very certain it can't create 1200W of mechanical power.  Probably 80-90% efficient.  No reason to expect it to consume exactly 1200W either.  My 500W power drill uses 750W of electricity.  When you snap in the speed reducer that could change its mechanical efficiency too.
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

DaveP68

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Re: Power factor correction capacitors used on wind turbine PMA's
« Reply #29 on: October 31, 2017, 05:38:12 PM »
Hi SparWeb

It's not about the drill actually having a shaft power of 1200 W exactly, it was for illustration purposes only. All those efficiency numbers could be 10 % lower. It's the difference between them, that is the most important factor. My testing outlined above to illustrate it another way is about Watts output vs RPM. So test # 1 is 1.13 W per 1 RPM, test # 2 is 1.775 W per 1 RPM,and test # 3 is 2.41 W per 1 RPM.

Anyway enough on that subject for now, I have an inductance reading 62.518 mH for 1 set of 12 poles (coils) of a 36 pole F&P stator. Hope this number is of use to you with the calculations you would like to make.

Next measurement will be voltage vs current phase angles in the AC winding in Delta mode.

David

Found an error so have edited the inductance value.
« Last Edit: October 31, 2017, 10:20:09 PM by DaveP68 »
There are realities that if you do not accept, will lead to frustration because you will be spending time on wrong assumptions and the results cannot follow!

joestue

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Re: Power factor correction capacitors used on wind turbine PMA's
« Reply #30 on: October 31, 2017, 11:33:48 PM »
how much additional current is flowing through the coils, as a percentage of practical load, when you add the capacitors?

DaveP68

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Re: Power factor correction capacitors used on wind turbine PMA's
« Reply #31 on: October 31, 2017, 11:59:15 PM »
Thanks XeonPony for the links re power factor correction, taking a bit of reading to get though them.

SparWeb has given me the clue to what is probably going on here. Now that I know the inductance of the coils 62.518 mH per phase, I've been able to calculate a resonant frequency 219 Hz 6 uF AC capacitors are connected.

That translates to 548 RPM which is why I notice such a large increase in the output power above 300 RPM.

Next step is to plot the power difference on a graph with output power no capacitors added 60 to 600 RPM and then carry out the same test with the capacitors connected over the same RPM range.

joestue

Was given a 3 channel storage scope today, so plan on taking some AC volts and current readings in the Delta windings this weekend.
There are realities that if you do not accept, will lead to frustration because you will be spending time on wrong assumptions and the results cannot follow!

SparWeb

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Re: Power factor correction capacitors used on wind turbine PMA's
« Reply #32 on: November 01, 2017, 01:12:56 PM »
Dave,
Glad to see you pursuing this.

Back in 2008, I tried to crunch the numbers - using my machine's stats - and published to Gordon's long caps-mod thread.
Below is a calculation sheet that I tried to "make pretty" for those interested in the math.


Later in that thread, I posted this, given some of Gordon's F&P parameters:



400 RPM, eh?

A few months after I posted that, an accident with my tower destroyed that wind turbine.  When I built the next one I never did pick up this subject again, until now.
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

kitestrings

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Re: Power factor correction capacitors used on wind turbine PMA's
« Reply #33 on: November 01, 2017, 08:20:46 PM »
Welcome to OP.

Quote
I'm no longer contributing to 'The Back Shed'

I'm sorry to hear this Dave.  As you know I murk about in the margins of several sites including The Back Shed.  I have less to contribute due to the alternator of predominant choice there, but still some interesting ideas.

With solar far and away the more popular choice these days, it's getting harder to find folks who are stubborn enough to still muck about with small-scale wind design.  Still watching a turbine is immensely more satisfying than a sunbathed PV array IMO.

~ks


SparWeb

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Re: Power factor correction capacitors used on wind turbine PMA's
« Reply #34 on: November 01, 2017, 11:15:34 PM »
Hi Dave,
The thing about the power drill is not trivial.
If you test in condition 1 and get one output curve, and then test in condition 2 and get another output curve, then all you know is that something changed.
But if you aren't watching the input power, then you could be mistaking a change in power with a change in speed range, or worse, fooling yourself that there is any improvement at all.  Even in the best case, you would want to know input power, to get the blades to match the generator characteristics.  If the blades get stalled, then no amount of capacitors on the generator will correct it.

As I said, I went back to the old threads on the Backshed and started re-reading them.  You'd better take a look at the comments from "HerbNZ" in the "Visual effect of capcitors" thread from GWatPE in particular, approximately page 20.  I don't think the inductance explanation has legs.  The other theories have merit, but by the time they were put forward, nobody still reading was interested in figuring out the rest.

I may have jumped to the wrong opinion when you started this subject.  Since that old thread was poorly resolved, and didn't offer any method to judge what capacitors to use when, despite being 40+ pages long, I think there's still room to step in and offer a better solution.  If you're willing to help, this will go faster than if I have to figure it out on my own.

To see the kind of test I'm talking about:  http://www.sparweb.ca/3_Gen_MoCo/Baldy.html

It's not necessary to go nuts with a lathe like that - I just had access to one, and it was big enough to drive the generator up to 2kW+.  For your tests, all you need to do is put the washer drum back in the washing machine and, presto, you have a smooth bearing-mounted axle that the F&P generator can drive, while a prony brake holds the drum.  Torque * RPM = Input power.    Output power / Input power = efficiency
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

DaveP68

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Re: Power factor correction capacitors used on wind turbine PMA's
« Reply #35 on: November 02, 2017, 12:40:03 AM »
Hi SparWeb

I haven't over looked what you are referring too with the drill, as I stated before "input shaft power was 1200 W". Again that isn't an exact figure but close enough.

One thing I've noticed on forums over time is many over read what isn't there in what I post ('m not picking on you here). I have done hundreds of hours of testing and yest do have an AC power meter monitoring what is going into the drill. All power readings you see are maximums taken over several tests taking into account input AC mains voltage to drill, power input reading of drill, temperature, how hot the drill gets, etc, etc.

All peak readings were taken first test of the day under colder conditions.

I can't accurately monitor the torque but that drill is hand held so I get to feel what happens each test so close enough for me.

The drill is providing a "maximum" reference point which just so happens to work in my favor. It has a 3 to 1 reduction gear box so the aim is to get a stator to output 1 kW at around 330 RPM. I know this is possible at in direct drive mode I can easily get 1 kW out of an F&P stator using the drill, but this is only achieved at above 900 RPM.

There is no chance of blade stall every happening when I use some form of MPPT after the stator. I already use a form of MPPT when doing my testing on these F&P stators just check out the voltages they run at which is the big give away (>400 VDC).

The reason why I post the YouTube video of the Pratt & Whitney PW1000G high-bypass geared turbofan, is Aviation is my main interest and I hold a pilots licence. I also worked at ATC at Auckland Airport a few years ago. There is a close relationship between aircraft and wind turbines.

This is just a hobby to me so have never made a dollar from it...
There are realities that if you do not accept, will lead to frustration because you will be spending time on wrong assumptions and the results cannot follow!

DaveP68

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Re: Power factor correction capacitors used on wind turbine PMA's
« Reply #36 on: November 02, 2017, 12:59:42 AM »
Welcome to OP.

Quote
I'm no longer contributing to 'The Back Shed'

I'm sorry to hear this Dave.  As you know I murk about in the margins of several sites including The Back Shed.  I have less to contribute due to the alternator of predominant choice there, but still some interesting ideas.

With solar far and away the more popular choice these days, it's getting harder to find folks who are stubborn enough to still muck about with small-scale wind design.  Still watching a turbine is immensely more satisfying than a sunbathed PV array IMO.

~ks

Hi ks

Thought you would notice my presence on here soon enough :)

It was the resident diesel mechanic and the farmer that drove me away from that website. I suspect some of the same types drove away Gordon who was a bright chap that many still talk about on there and the same chap made reference too in this topic. Shame as I think he still had lots to offer.

Anyway having a much better experience over here so far  :D
There are realities that if you do not accept, will lead to frustration because you will be spending time on wrong assumptions and the results cannot follow!

SparWeb

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Re: Power factor correction capacitors used on wind turbine PMA's
« Reply #37 on: November 02, 2017, 12:55:54 PM »
Cool Dave,
I could tell you had some smarts about you.
I do a bit of aircraft work, too; modifications like the Australian Coast Guard's turboprops (DHC-8-100).

Quote
... with the drill, as I stated before "input shaft power was 1200 W". Again that isn't an exact figure but close enough.
The chances of that being true are small.  Sorry.

Quote
I can't accurately monitor the torque...
Sure you can.  Once you get your head around it, it can be as easy as a C-clamp, a board, and a bathroom scale.

Quote
...drove me away from that website...
Their loss
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

SparWeb

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Re: Power factor correction capacitors used on wind turbine PMA's
« Reply #38 on: November 02, 2017, 01:03:47 PM »
Wait a minute - if you have two F&P motors, and convert 1, you can use the other as the drive for testing. 
Looking at your other thread about mods to the motor controller, it looks like you have already started on this path...
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

DaveP68

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Re: Power factor correction capacitors used on wind turbine PMA's
« Reply #39 on: November 02, 2017, 02:00:38 PM »
Hi SparWeb

Thanks for the endorsement. Yes working on the torque measurement technique using "C-clamp, a board, and a bathroom scale" to capture the input power component. Haven't bother to date as holding drill was just easier.

David
There are realities that if you do not accept, will lead to frustration because you will be spending time on wrong assumptions and the results cannot follow!

DaveP68

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Re: Power factor correction capacitors used on wind turbine PMA's
« Reply #40 on: November 03, 2017, 10:23:16 PM »
For those following this topic, today graphed the power output difference with capacitors connected to the stator and with no capacitors.
10891-0

That is a greater than 2 to 1 gain in power output vs RPM and I didn't even reach the peak which by calculations is at just over 500 RPM.

The peak power was 852 W at 375 RPM as can be seen on the graph (Green line).
There are realities that if you do not accept, will lead to frustration because you will be spending time on wrong assumptions and the results cannot follow!