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RevUpWind Regular Member Joined: 03/05/2008 Location: AustraliaPosts: 60
Posted: 11:28pm 09 Feb 2009
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Sorry folks ignore last post, was only a draft of an
earlier one. ....River Heads - Australia
The wind blows wherever it wishes; you hear the sound it makes, but you do not know where it comes from or where it is going.
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 11:41pm 09 Feb 2009
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Deleted by me. Gave up waiting. Edited by GWatPE 2009-02-12become more energy aware
RevUpWind Regular Member Joined: 03/05/2008 Location: AustraliaPosts: 60
Posted: 03:06am 10 Feb 2009
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Yes it tis the browser, using Google Chrome which is very good but not in this case.
Yes just changed my website to .org as .com is down. Not too relevant to this form and think will revmove the link.
Cheers
Peter....River Heads - Australia
The wind blows wherever it wishes; you hear the sound it makes, but you do not know where it comes from or where it is going.
RevUpWind Regular Member Joined: 03/05/2008 Location: AustraliaPosts: 60
Posted: 03:22am 10 Feb 2009
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Hello GWatPE, have no edit tab on that incorrect post so cannot remove.
The corrected one was already posted on previous page and I came along and mistakenly posted the draft. Can you remove it?....River Heads - Australia
The wind blows wherever it wishes; you hear the sound it makes, but you do not know where it comes from or where it is going.
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 05:27am 10 Feb 2009
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I cannot see how this is so. No I cannot edit your posts, but you can. You need to read what follows.
Use the EDIT button at the botttom of the post window, then update post with the changes. You do need to be logged in as well to see the EDIT button.
here are examples. See if you can spot the differences.
The first one is when I was not logged in.
This one is when I was logged in.
It is not really much more difficult than updating your profile, which you have already done.
Gordon.
PS edit: Many readers have edited out posts, so you should be able to as well.Edited by GWatPE 2009-02-12become more energy aware
RevUpWind Regular Member Joined: 03/05/2008 Location: AustraliaPosts: 60
Posted: 12:36am 11 Feb 2009
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Regarding Betz or Betts law/ limit or whatever Let's think outside the circle; Literally.
Betz law assumes a non real world cylinder of air which passes through the turbine blades and cannot be slowed down to 100%.
In the real world this cylinder of air does slow down but it also compresses and ignoring the inner part of the turbine for the moment, the wind spirals out towards the tip of the blade being an area of least resistance where it speeds past and rapidly returns behind the blade to fill the partial vacuum behind.
Betz law assumes that if you present a flat disc to the wind and stop the whole column of wind that no rotation of the disc would be observed.
This is true. However I can still make use of the wind in the real world that accelerates around the edge of the disc under pressure and being sucked back in.
E.G. Put the flat disc in place as your turbine and mount trailing turbine blades at right angles to the disc but fully within the limits of the cylinder and see what happens. Yes it will turn and make power!
This is the portion of wind that I am experimenting with to boost the performance of wind turbines. (small ones)
One of the rationalizations behind this idea is the fact that the effect of wind at the tip is likely to be a cubed factor increase over the centre portion of the turbine. So any benefits obtained at the tip are benefits indeed.
Laws are made to be broken. That is true science.
Dealing with losses occuring in the middle is another subject.Edited by RevUpWind 2009-02-12....River Heads - Australia
The wind blows wherever it wishes; you hear the sound it makes, but you do not know where it comes from or where it is going.
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 04:27am 11 Feb 2009
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I think continued discussion of blades would be better suited to a new thread.
Gordon.become more energy aware
herbnz Senior Member Joined: 18/02/2007 Location: New ZealandPosts: 258
Posted: 08:09pm 13 Feb 2009
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Hi By god he's got it .
Its about time to start another thread that deals with alternator theory. Many ppl are jumping in at the deep end with no idea of the basics so going back to beginning and building up to caps etc would be of benifit. I cannot seem to get into a writing mode these days but will try to make a effort
Herb
thaelin Newbie Joined: 14/02/2009 Location: United StatesPosts: 4
Posted: 06:12pm 14 Feb 2009
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Hi all:
Just joined in from across the big pond from you. Have been reading here on caps and resonance how it related to the coils of the gen. I have been searching for a low speed gen for a new type of mover for some time now. All have been to high of rpm's.
A few pages back a comment was made to the effect of it is a shame we don't have a constant speed mill. Well that is basicly what I have in mind. By adjusting the length of runner for the switches you can vary its speed to some extent.
I am using a large stepper motor right now for a gen head. It howls very bad but is capable of 5 amps at around 25v which is enough for its conformation. Where you fellas use wind, I have used gravity. The use of the caps to all but double the output of the gen head and lower the cutin speed is what caught me.
I of course will not be able to find a F/P motor over here but since you have posted pics of its internals, one could very easily be made and migrated to my system
If this is not in topic here, then plz move to a comfortable place. I will be posting a few pics shortly and then a movie of it in operation.
thaelin
KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691
Posted: 07:29pm 14 Feb 2009
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Hi Thaelin and welcome to the Back Shed.
You seem to have an interesting project and it sounds like it is worthy of its own topic, may I suggest either here (if it relates to windmills) or in the Stuff.Edited by KiwiJohn 2009-02-16
thaelin Newbie Joined: 14/02/2009 Location: United StatesPosts: 4
Posted: 09:59pm 15 Feb 2009
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First try at this failed so will post again with it.
I just hooked up my big stepper with two seperate coil sets in a three wire setup. From those three wires I hooked back to back 1000uf 400v caps before the bridge set.I am seeing double the output there abouts. Open circuit I can see 30v and it shows 4 amps with a 12v car head lamp on it. Should be great for the inital run. Then to wire up a gen head as talked about here for the final.
Will have to wait till wednesday for a part I broke as I am not sure where to get more close by.
I will be opening up a thread in Stuff for the rest of the writeup on my project. Cheers.
thaelin
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 04:42am 19 Feb 2009
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Some recent developments.
The capacitor voltage doubler on Bolty's mill [1kW chinese style] works very effectively, but the cutin could be lower still. A voltage trippler with varying capacitor sizes may be a better option. This will be tested at the earliest opportunity.
Gordon.become more energy aware
Bolty Regular Member Joined: 03/04/2008 Location: AustraliaPosts: 81
Posted: 07:22am 19 Feb 2009
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As Gordon has suggested we thought out the idea of using
a voltage tripler to get more low end generation going
back to the grid. At present, my turbine can be spinning
and producing 53 volts DC. My controller connects the
turbine to the grid connect inverter at 54 volts. Hence
at 53 volts, no power is being generated, although
around 20 to 30 watts could be if connected. The idea
was to add an extra 3 phase bridge in series with the 2
existing doubler bridges, effectively tripling the AC.
We realized that this would then produce a considerably
higher voltage, but with very little power. This would
cause the grid connect inverter to overload the turbine,
probably causing it to stall. Hence we came up with the
idea of using a lower value capacitor bank in the extra
tripler bridge. This would limit the loading effect of
the inverter on the turbine, allowing it to spin and
still produce more than 53 volts.
Thinking on further, we soon realized that the loading
characteristic could be appropriately shaped by
judiciously choosing different capacitor values for each
of the 3 bridges in series. At present my doubler has
470 uF back to back on each of the 6 legs. Gordon is
suggesting trying 100 uF as the lower value with around
220uF or 330 uF for the intermediate, and retaing the
470uF for the largest.
What I see of considerable merit with this, is that it
will not change the existing doubler (except if I reduce
the capacitor value to 330 uF) but the extra tripler
should give me extra voltage (and hence exceed 54 volts
to produce power) This should have the effect of
outputting 20 watts or so for much of the time that I
now get nothing.
We will post again when we have some results of these
ideas!
Bolty Regular Member Joined: 03/04/2008 Location: AustraliaPosts: 81
Posted: 02:09pm 19 Feb 2009
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I have done some testing with extra capacitors. Because
Gordon loaned me a doubler using back to back 330uF
capacitors. I thought that I would try adding this in
series with the existing 470uF doubler, effectively
making a quadrupler. The low end performance has been
dramatically improved, with the cut in for connection to
to the grid-connect inverter now being 80 rpm. Before
adding the extra doubler, the cut in was 173 rpm. There
appears to be no excessive loading by the early
connection, as when the inverter connects, there is no
excessive reduction in turbine rpm. This means that I am
now getting a lot more low end power. 24 hours of 30
watts equates to an extra 0.72 kwhr, virtually for no
cost!
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 08:18pm 19 Feb 2009
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I am guessing that the inverter spends a lot less time in synchronizing mode, and this should also make for more watts into the grid.
Looks another promising idea from that man full of ideas over there
..........oztulesVillage idiot...or... just another hack out of his depth
Bolty Regular Member Joined: 03/04/2008 Location: AustraliaPosts: 81
Posted: 11:29pm 19 Feb 2009
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Hi Oztules. Gordon has told me a lot about your
situation on Flinders Island. I certainly envy your life
style there, as I am not a city person. Living at Victor
Harbor A(right next to Port Elliot) is sometimes too
close for me to suburbia. I also am impressed with the
wind regime you get there. Our wind is very ordinary and
usually highly turbulent when we do get it. Gordon,
being closer to the sea gets a much more consistent
pattern.
However I have to work with what I have and optimize it!
The Latronics inverter has not been a problem with
synchronizing due to holding on for about 15 mins of no
wind. This extra doubler gives me the very low cut-in
speed. I realize that it is not a huge amount of energy,
but every little bit counts, especially when it is so
easy to get this extra!
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 02:22pm 22 Feb 2009
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An update on some capacitor sizes for a voltage doubler on a Series80 rewire for 24V system.
I have a series80 7s2p rewire on 24V. I have finally replaced the picaxe programmed variable boost DC-DC converter with a low voltage cutin voltage doubler. The capacitors are NP audio caps, 100V rating, electrolytic type. I have used 2x33uF in parallel in each rectifier input of the voltage doubler. This is 66uF. There are 12 caps in total. Total cost $24 for caps, and $12 for rectifiers. These only have to pass a max of 2-3A. My F&P mill now has full AC coupling to the load, and no electronic switching. The windmill now loads very smoothly and really starts providing current as soon as it starts turning. I have seen 2-5mA AC at 20-30rpm. The mill does not seem to become overloaded and the rpm follows the windspeed much more smoothly than the DC-DC boost converter. Not having a computer try and work out what to do, and having a natural system behaviour do it, seems to result in more time closer to the optimum. The voltage doubler is assisted by the normal rectifiers to the battery when the load current reaches 0.6A. I have to wait for more weather to record some loadings at higher power levels, and check these caps for long term suitability.
Gordon.
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oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 09:08pm 22 Feb 2009
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Gordon,
This is starting to feel like some refinement is happening. It will be interesting to see how the new setup works with higher wind speeds, and what it can deliver ultimately. Does this also have the 48v grid tie running as well, or battery duty only?
I know you were getting some serious output into batteries and inverter, but how does it behave on battery duty only (like I expect most here will be doing).
.........oztulesVillage idiot...or... just another hack out of his depth
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 11:34pm 22 Feb 2009
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Hi oztules,
I still have the 24V battery loading at low power levels only. As the wind energy levels rise, and the rotor rpm increases, the generated emf may be sufficient to allow power to feed the 48V grid inverter as well.
So far, for low power levels up to 10W, goes via voltage doubler only to battery. At 80W, 1ADC is via the doubler, and an additional 2ADC is through normal 24V cap coupled rectifiers. At this point the 48V cct just achieves cutin.
This is the measured performance so far.
For each doubling of the generated AC output voltage, there is an 8fold increase in the power to the load. This is sort of what is required from the windmill.
Without the 48V loading, the windmill speeds up more, and the tsr increases. The caps on the 24V system do more work for similar output power levels. I have not fully tested this, as the windmill braking becomes enabled as the battery is fully charged, and the capacity of the grid loading at 24V becomes exceeded at these power levels. This is why I opted for 48V direct loading to the grid inverter as well.
As long as the battery diversion loading is working for the max expected power levels, all will be OK.
Gordon.
PS edit:
One aspect of the capacitor coupling that I thought other learned readers may have picked up on is that there is no real way to compensate the loading reigime for varying state of charge voltages that will be presented by the battery during typical usage. If the battery is very flat, it will present a bigger loading, and if the battery is fully charged, this will be a lower loading. The electronic switching system is able to be programmed to compensate for this, as is what I have done on the picaxe, and my analogue DC-DC variable boost converters.
At present, the blade tsr seems to adapt to the varying loading and all seems to still be OK.Edited by GWatPE 2009-02-24become more energy aware
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 12:06pm 03 Mar 2009
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Hi thaelin,
Will be good to see how you are proceeding with your testing.
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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as I am not sure where to get more close by.
