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21
Wind Power Machines / Re: Interfacing wind turbines to the grid
Last post by MaryB -
Quote from: SparWeb – on
Quote from: bigrockcandymountain – on
What if all you did was add a very large capacitor (or a few of them) with a resistor in series to limit charge /discharge amps between positive and negative between the ssr and the micro inverter? Would it smooth the dc power enough that the micro would be happy? Would it store enough that when the mppt swept up it would drop a bit of amps and mimic a solar panel?

Funny you mentioned the SSR just when I was getting frustrated with designing my circuit with a MOSFET, and tonight I've been replacing it with a SSR.

I think I have the microcontroller signals figured out.  What's really bothering me now is that I've made some assumption about the inverter and I don't like the way things go bad if I am wrong.  I've been using Falstad's site to simulate this, and it suggests I will be blasting the 0.5 ohm power resistor with brief bursts of 90 amps.   Probably just something I have simulated wrong, but...

To your suggestion BRCM, yup, a big capacitor soaks up a lot of nuisance noise.  You just have to make sure it doesn't drown out the signal you want to measure.  Circuits that combine resistors and capacitors have a "time constant".  If the constant is long (in the electronics world 1 millisecond is long) then the time for the capacitor to charge up is longer than the time for a 1 kiloHertz signal to arrive, and you probably won't measure the signal.  On the other hand, if the capacitor is too small or ineffective, then the microcontroller is measuring pulses and it may pick up the pulse on the Hi during one reading, and on the Lo on the next.  From the microcontroller's perspective, the signal went from on to off, and in a sense, it would be right.  But in another sense it failed to detect what the power resistors are doing.  It missed the next Hi peak which has a different voltage than the last Hi peak, and that was the information it's looking for.  So there's a balance, when Goldilocks finds the right oatmeal.

Quote from: bigrockcandymountain – on
It sounds like a thread hijack when I read through it, but it kind of applies to sparweb's setup too.

Nah, you're forgiven

Most resistors have it buried somewhere in the spec sheet for a certain time it can handle an overload...

1.7 Pr 5 s for R < 2 Ω this example is 1.7 times the power rating for 5 seconds for a .5ohm 35watt

If you have a part number or maker/value used I can look up the spec....
22
General Discussion / Re: How is everyone surviving the cold and snow?
Last post by Bruce S -
Late to the party I see.
Well, the snow came along with unusually frigid here in St. Louis. Of course the people trying to just stay warm cause a 4-alarm fire, ( no one harmed and warming buses called in once it hit 3-alarm kept most from suffering).
Big talk was the extreme cold and freezing hose links.
Snow pretty with sunshine bouncing off it. Panels are almost completely cleaned off.
Got to try out the diesel heater to keep early start veggies warm. I'm liking the ability to tweak the fuel to just keep things warm enough to not get frost stress. Peppers and Sage do not like cold at all.
Consumption is pretty good to 3-day amount tested before I left for work this morning was just a hair over 10 liters. Any lower and the inside temps got too low for my liking. I use a mix of diesel /veggie/& Unleaded total cost? ~$5USD Being able to pick peppers while snow is falling and covering over old Jack Russell terrier ? Priceless  :)) 
Almost forgot. Growing area is a 10'Wx14'Lx9'H
25
General Discussion / Re: How is everyone surviving the cold and snow?
Last post by MaryB -
The short days cut my solar output, but I get gain from snow reflection... not enough to cancel the short days but it helps. Dec thru Feb I see a reduction in output. With my panels at 45 degrees snow tends to slide off. Yep I am at 44.5 north!
26
General Discussion / Re: How is everyone surviving the cold and snow?
Last post by MagnetJuice -
I am fortunate to live where I live. The coldest I’ve seen this winter is -3C. We get a lot of rain here through the winter but to me that’s better than the cold and freezing weather. I hope those living in the southeast US make it through OK. That looks like a really nasty storm.

Spar, for those that have panels close to the ground, it should not be too difficult to build a rack that would pivot, then use an actuator to flip the panels down 30 or 35 degrees. They could be flipped when there is a lot of snow in the way, then moved back after the storm. BigRock and kitestrings have used actuators successfully with their wind turbines.

Stay warm guys.

Ed
28
Wind Power Machines / Re: Interfacing wind turbines to the grid
Last post by SparWeb -
Quote from: bigrockcandymountain – on
What if all you did was add a very large capacitor (or a few of them) with a resistor in series to limit charge /discharge amps between positive and negative between the ssr and the micro inverter? Would it smooth the dc power enough that the micro would be happy? Would it store enough that when the mppt swept up it would drop a bit of amps and mimic a solar panel?

Funny you mentioned the SSR just when I was getting frustrated with designing my circuit with a MOSFET, and tonight I've been replacing it with a SSR.

I think I have the microcontroller signals figured out.  What's really bothering me now is that I've made some assumption about the inverter and I don't like the way things go bad if I am wrong.  I've been using Falstad's site to simulate this, and it suggests I will be blasting the 0.5 ohm power resistor with brief bursts of 90 amps.   Probably just something I have simulated wrong, but...

To your suggestion BRCM, yup, a big capacitor soaks up a lot of nuisance noise.  You just have to make sure it doesn't drown out the signal you want to measure.  Circuits that combine resistors and capacitors have a "time constant".  If the constant is long (in the electronics world 1 millisecond is long) then the time for the capacitor to charge up is longer than the time for a 1 kiloHertz signal to arrive, and you probably won't measure the signal.  On the other hand, if the capacitor is too small or ineffective, then the microcontroller is measuring pulses and it may pick up the pulse on the Hi during one reading, and on the Lo on the next.  From the microcontroller's perspective, the signal went from on to off, and in a sense, it would be right.  But in another sense it failed to detect what the power resistors are doing.  It missed the next Hi peak which has a different voltage than the last Hi peak, and that was the information it's looking for.  So there's a balance, when Goldilocks finds the right oatmeal.

Quote from: bigrockcandymountain – on
It sounds like a thread hijack when I read through it, but it kind of applies to sparweb's setup too.

Nah, you're forgiven
29
Wind Power Machines / Re: Interfacing wind turbines to the grid
Last post by SparWeb -
Quote from: bigrockcandymountain – on
...my diversion load is a 500hz 12v signal that goes to a ssr and dumps the 48v battery voltage through an approx 10ohm resistor (water heater element) I assume the 48v comes out of the ssr at 500hz, not exactly as dc.

48v/10 ohms = 4.8 Amps
60v/10 ohms = 6.0 Amps

Hmm surely you'd dump more than that?  I think your WT is bigger than mine is, and I need a 2kW diversion load (and I admit mine turns out to be only 1.8kW).  It may not matter in your case if you're using your batteries most of the time.