"Smitty Two" wrote in message
news

I've chewed this over a bit, and I still don't like it, and here are my
reasons:

1: Voltage sources in parallel do not push *against* one another.

2: If no voltage source can join the grid without being at a higher than
grid potential, then every contributing power station would have to be
at a higher potential than every other one, and that's impossible.

3: While voltage might *push*, it's the load that it said to *pull* the
current. If there's a demand, current will flow whether the supply
voltage is 119, 120 or 121.


Where is my thinking flawed?

But... but... but... EVERY car insurance company is cheaper than its
competitors and every alkaline cell is the longest lasting... LOL

Seriously, the power stations are not higher than each other, but every one
is higher than the grid, imagine three power stations, or 3 generators in
the same station all putting out exactly 48KV, the substation/transformer
they are connected to is getting slightly less, say 47,990 volts. If they
then need to bring a fourth generator online they use a syncroscope to
adjust the prime mover to sync up the frequency and phase, adjust the field
to match the voltage IE 47,990, close the breakers, and slowly increase the
field and prime mover so that the load is shared and now all 4 are at 48KV.

On 4/17/2011 7:19 PM Jim Wilkins spake thus:

On Apr 17, 9:15 pm, Smitty Two wrote:

...
Where is my thinking flawed?

It makes more sense if you think of the inverter as forcing a constant
CURRENT and let the voltages be whatever the source (wire etc)
resistance makes them at that current.

The grid may or may not act like an infinite sink. The continual load
variations will probably swamp out any voltage measurement you might
make, so it's reasonable to consider it an infinite sink unless you
have a very large inverter. The GTI wants to dump all the current from
the array onto the line and will adapt itself to the line voltage,
whatever it may be.

If you connect a PV panel to a 12V battery the panel will source as
much current as the sunlight produces, at the voltage of the battery
even if the panel's open circuit voltage is above 20V. The battery
voltage will rise a little because of the IR drop in its internal
resistance.

http://en.wikipedia.org/wiki/Current_source

It *sounds*--and I'm sure you'll correct me if I'm wrong--as if you're
agreeing with me, and with Smitty, and others when we say that it is
*not* required that the photovoltaic inverter supply a higher voltage in
order to transfer current to the grid. (I take this from the last
sentence in the next-to-last paragraph, where you say " ... will adapt
itself to the line voltage, whatever it may be".)

The arguments against this, with all the pseudo-science being thrown
around (most of it by the ones who are also slinging insults) are
getting quite tiresome here.


--
The current state of literacy in our advanced civilization:

yo
wassup
nuttin
wan2 hang
k
where
here
k
l8tr
by

- from Usenet (what's *that*?)

On Sun, 17 Apr 2011 20:40:37 -0700, David Nebenzahl
wrote:

On 4/17/2011 7:19 PM Jim Wilkins spake thus:

On Apr 17, 9:15 pm, Smitty Two wrote:

...
Where is my thinking flawed?

It makes more sense if you think of the inverter as forcing a constant
CURRENT and let the voltages be whatever the source (wire etc)
resistance makes them at that current.

The grid may or may not act like an infinite sink. The continual load
variations will probably swamp out any voltage measurement you might
make, so it's reasonable to consider it an infinite sink unless you
have a very large inverter. The GTI wants to dump all the current from
the array onto the line and will adapt itself to the line voltage,
whatever it may be.

If you connect a PV panel to a 12V battery the panel will source as
much current as the sunlight produces, at the voltage of the battery
even if the panel's open circuit voltage is above 20V. The battery
voltage will rise a little because of the IR drop in its internal
resistance.

http://en.wikipedia.org/wiki/Current_source

It *sounds*--and I'm sure you'll correct me if I'm wrong--as if you're
agreeing with me, and with Smitty, and others when we say that it is
*not* required that the photovoltaic inverter supply a higher voltage in
order to transfer current to the grid. (I take this from the last
sentence in the next-to-last paragraph, where you say " ... will adapt
itself to the line voltage, whatever it may be".)

No, the voltage will STILL be higher if you're supplying current to the grid.
Wires have resistance. Current sources don't go against physics and really
are the same thing as voltage sources (Norton/Thevenin duality). Physics
doesn't lie.

The arguments against this, with all the pseudo-science being thrown
around (most of it by the ones who are also slinging insults) are
getting quite tiresome here.

You're throwing around the pseudo-science. If you don't like the treatment,
you can easily leave.

On 17/04/2011 14:27, wrote:

You're wasting your time with Mho. He obviously isn't interested in
figuring out anything. I provided a detailed circuit analysis that
shows bringing an additonal power source online will result in
a slightly higher voltage at the grid and the load, provided
everything
else stays the same. The example was a FIXED load. I only
pointed out that one alternative to raising the grid voltage is that
the load could instead increase

His silly short response makes no sense at all.




Well, I was just teasing him, did not really expect any answer.

On 17/04/2011 20:40, David Nebenzahl wrote:

It *sounds*--and I'm sure you'll correct me if I'm wrong--as if you're
agreeing with me, and with Smitty, and others when we say that it is
*not* required that the photovoltaic inverter supply a higher voltage in
order to transfer current to the grid. (I take this from the last
sentence in the next-to-last paragraph, where you say " ... will adapt
itself to the line voltage, whatever it may be".)

The arguments against this, with all the pseudo-science being thrown
around (most of it by the ones who are also slinging insults) are
getting quite tiresome here.



If you take the voltage drops into account, the voltage at the inverter
has to be higher than the voltage at the grid connection point.

This is a real world scenario.

On Apr 17, 9:29*pm, "
wrote:
On Sun, 17 Apr 2011 17:43:09 -0700 (PDT), The Ghost in The Machine





wrote:
On Apr 15, 11:45*pm, "
wrote:
On Fri, 15 Apr 2011 20:03:02 -0700 (PDT), The Ghost in The Machine

wrote:
On Apr 14, 12:23 am, "
wrote:
On Wed, 13 Apr 2011 20:46:43 -0700 (PDT), The Ghost in The Machine

wrote:
On Apr 13, 11:38 pm, "
wrote:
On Wed, 13 Apr 2011 21:33:08 -0400, "vaughn"
wrote:

wrote in message
news

E=IR, certainly *IS* Ohm's law. I and E are proportional. You can't increase
I without increasing E.
Wrong. You CAN increase I without increasing E. You have 3 variables in that
formula, not just 2.

Dumbass, it's a fixed circuit.

Get it? I suppose not.

Apparently not.

You've only proved that you're just as stupid as David.

SO, NOW WE ALL SHOULD RESORT TO ANGRY NAMECALLING & FAGGOTY RESPONSES
HAHN???

GROW UP FOOL, OR DROP IT, YOUR STALE INSIGNIFICANT DULLARD POSTINGS
ARENT HELPING ANY.

Speaking of dumbasses...

PAT ECUM

Here is Roy Queerjano, A.K.A. Pat E. Cum/

DANNNNNNNNT WRONG !!!!

"DANNNNNNNNNT"? *That word isn't in my dictionary, Roy Queerjano?

YOU SHOULD SHUT UP DONKEY KELLY WE KNOW ALL ABOUT YOU AND MICHAEL
TERRELL'S *GAYTARD BROKEN HEART OVER ROY Q...YOU FOOL....FYI I AM NOT
HIM ......YOU SYCOPHANTIC USENET ABUSER.

You're a liar, Roy Eat Cum.

COLLECTING AND DELIVERING YOUR HATEFUL OPPRESSIVE RESENTFUL SOUL TO
HELL WILL BE A TREAT TO MANKIND.

Go away, Roy.

THIS ROY YOU KEEP BRINGING UP, HAVE YOU BEEN PERFORMING FELLATIO ON
HIM???

No, Roy, you are *not* my type. *Now go *away*!

YOU MUST BE IN LOVE WITH HIM, YOU QUEER, SEEMS HE HAS GOT YOU ALL UP
IN A TIZZY, KIZZY.

Isn't it cute when Roy Queerjano accuses others of being what he *is*.

I HOPE YOU TWO LIVE IN ONE OF THOSE LEGAL GAYTARD MARRIAGE STATES, ID
HATE TO HAVE YOU BACK IN HERE CRYING AND WHINING ABOUT HOW YOUR TWINKY
LITTLE HEART IS BROKEN CAUSE YOU CANT MARRY
HIM ....BWAHAHAHAJAHAHA !

Sorry, Pat Eats Cum, I'm already married - longer than you've been alive,
moron.

AND IT'S MR. ECUM TO YOU FOOL.

No it's *not*, Roy.

IF YOU ARE MARRIED THEN WHY DO YOU KEEP FANTASIZING ABOUT THIS FELLOW
ROY THAT I SEEM TO REMIND YOU AND SEVERAL OTHER USENET CLOSET CASES
OF???

DOESNT YOUR HUSBAND MAKE YOU HAPPY.....?

I SEE YOU ALSO HAVE A PERVERTED SEMEN FETISH, YOU DEVIANT!!

PLEASE LEAVE OUR USENET GROUPS AND PERSUE YOUR TWISTED FANCY IN SOME
DATING SERVICE FOR UNHAPPLIY WED PERSONS LIKE YOURSELF, OR TAKE IT
ELSEWHERE FELLER, WE'RE NOT IN THE MOOD FOR YOUR MANBOY CRAVING
SHENANIGANS.

PATECUM

On Apr 17, 11:49*pm, "
wrote:
On Sun, 17 Apr 2011 20:40:37 -0700, David Nebenzahl
wrote:





On 4/17/2011 7:19 PM Jim Wilkins spake thus:

On Apr 17, 9:15 pm, Smitty Two wrote:

...
Where is my thinking flawed?

It makes more sense if you think of the inverter as forcing a constant
CURRENT and let the voltages be whatever the source (wire etc)
resistance makes them at that current.

The grid may or may not act like an infinite sink. The continual load
variations will probably swamp out any voltage measurement you might
make, so it's reasonable to consider it an infinite sink unless you
have a very large inverter. The GTI wants to dump all the current from
the array onto the line and will adapt itself to the line voltage,
whatever it may be.

If you connect a PV panel to a 12V battery the panel will source as
much current as the sunlight produces, at the voltage of the battery
even if the panel's open circuit voltage is above 20V. The battery
voltage will rise a little because of the IR drop in its internal
resistance.

http://en.wikipedia.org/wiki/Current_source

It *sounds*--and I'm sure you'll correct me if I'm wrong--as if you're
agreeing with me, and with Smitty, and others when we say that it is
*not* required that the photovoltaic inverter supply a higher voltage in
order to transfer current to the grid. (I take this from the last
sentence in the next-to-last paragraph, where you say " ... will adapt
itself to the line voltage, whatever it may be".)

No, the voltage will STILL be higher if you're supplying current to the grid.
Wires have resistance. *Current sources don't go against physics and really
are the same thing as voltage sources (Norton/Thevenin duality). *Physics
doesn't lie. *

The arguments against this, with all the pseudo-science being thrown
around (most of it by the ones who are also slinging insults) are
getting quite tiresome here.

You're throwing around the pseudo-science. *If you don't like the treatment,
you can easily leave. *

SO!' BY NOW YOU'VE CONSUMED YOU DOSE OF CRACK AND ARE NOW SPEWING YOUR
MEGALOMANIACAL COCAINE PSYCHOSIS CRAP...

ONLY DIFFERENCE IS NOW YOU ARE PICKING ON DAVID NEBUCADNEZAR?
DOES HE EXCITE YOU LIKE THIS ROY YOU KEEP DREAMING OF???

IT IS YOU THAT SHOULD LEAVE....QUEERAZOID.
OR STOP IT WITH THE FAGGOTY PERSONAL ATTACKS ALREADY, WE DO NOT CARE
NOR WANT TO KNOW YOUR PERSONAL LIKES, LIFESTYLE CHOICE OR
MATERIALISTIC DELUSIONS,. WE'RE JUST HERE TO DISCUSS ENERGY AND
HOMEPOWER, NOT HOMOPOWER.....GOODBYE!

PATECUM
TGINTM CO. INC.
[NET DRIVE]

On Apr 18, 12:29*am, g wrote:
On 17/04/2011 20:40, David Nebenzahl wrote:

It *sounds*--and I'm sure you'll correct me if I'm wrong--as if you're
agreeing with me, and with Smitty, and others when we say that it is
*not* required that the photovoltaic inverter supply a higher voltage in
order to transfer current to the grid. (I take this from the last
sentence in the next-to-last paragraph, where you say " ... will adapt
itself to the line voltage, whatever it may be".)

The arguments against this, with all the pseudo-science being thrown
around (most of it by the ones who are also slinging insults) are
getting quite tiresome here.

If you take the voltage drops into account, the voltage at the inverter
has to be higher than the voltage at the grid connection point.

This is a real world scenario.

YOUR PRIOR STATEMENT IS CORRECT IN THEORY ONLY, BUT ACTUALLY, THE
VOLTAGE NEED NOT BE HIGHER FOR HARMONIC DISPLACEMENT INTO THE GRID.

AND SO: IN THEORY THE DEMAND ON THE GRID WOULD DRAW FROM THE PATH OF
LESS RESISTANCE, HENCE, IN THE CASE OF A GRID TIDE PRODUCT AS THE
SUGGESTED SOLAR PANEL SYSTEM, WITH A CHARGE OF EQUAL PROPORTION BUT
LESSER RESISTANCE, AGAIN, IN THEORY, THE DEMAND WOULD FALL UPON THIS
LESSER SYSYEM.
THEREFO SUCH A SYSTEM IS NOT RECOMMENDED FOR GRID CONSUMPTION.
BUT HIGHLY RECOMMENDED FOR LOCAL CLOSED DISTRIBUTION.

((LICENSING REQUIRED FOR OTHER THAN PRIVATE USE))

PATECUM
TGITM - NET DRIVE

On Apr 17, 11:40*pm, David Nebenzahl wrote:
On 4/17/2011 7:19 PM Jim Wilkins spake thus:
...
It *sounds*--and I'm sure you'll correct me if I'm wrong--as if you're
agreeing with me, and with Smitty, and others when we say that it is
*not* required that the photovoltaic inverter supply a higher voltage in
order to transfer current to the grid. (I take this from the last
sentence in the next-to-last paragraph, where you say " ... will adapt
itself to the line voltage, whatever it may be".)

The inverter output is higher -internally- by the V=IR drop between it
and the grid.

In this case I is the independent variable, the array's output, and V
is whatever it takes to make I pass through R to get to the grid
voltage.

jsw

g wrote:
On 17/04/2011 14:27, wrote:

You're wasting your time with Mho. He obviously isn't interested in
figuring out anything. I provided a detailed circuit analysis that
shows bringing an additonal power source online will result in
a slightly higher voltage at the grid and the load, provided
everything
else stays the same. The example was a FIXED load. I only
pointed out that one alternative to raising the grid voltage is that
the load could instead increase

His silly short response makes no sense at all.




Well, I was just teasing him, did not really expect any answer.

Pigs-arse you were "teasing". You were sucked in
by the GymmyBob troll.. another of a few hundred
of his 'victims'. Deservedly so on this occasion.. you
prove a clueless dolt.

Get yourself educated on "how to" in reading news, rube.
netscape.public.mozilla.general

Then go check out your 'victor' :-/
"Gymy Bob" /3auj4kc
"John P. Bengi" /3zgxjxa
"Solar Flare" /42ytgkq
"Pizzza Girl" /3p979nm
"Janice" /3bctgwr
"Joesepi" /3qkwmxr

... mind how you go. Don't want you
bleeding all over the place:-D

To Smitty

I've chewed this over a bit, and I still don't like it, and here are my
reasons:

1: Voltage sources in parallel do not push *against* one another.


You can't have two voltage sources EXACTLY in parallel, its like
dividing by 0. There is always some small resistance between voltage
sources or the sources themselves have resistance.


2: If no voltage source can join the grid without being at a higher than
grid potential, then every contributingpowerstation would have to be
at a higher potential than every other one, and that's impossible.


The sources have to be higher then the grid, not higher then eaach
other. Lets say the grid is some point in the middle of a square and
it is at 120.0. Lets say there are 4 sources feeding that center
point from the 4 corners. Each feed has a small resistance between it
and the "grid point". Each one can be at 120.1 for example and power
will flow from each to the grid point. If feed point one is a big
nuclear plant it might be at 120.3 and your small solar plant at point
2 might be at 120.01. But each will feed power TO the grid point
load. Each plant adjusts itself to the right slight increse in voltage
to feed the amount of power it has avaialbe.

(This is an oversimplification of what really happens. What really
happens also has a lot to do with frequency and phase.)



3: While voltage might *push*, it's the load that it said to *pull* the
current. If there's a demand, current will flow whether the supply
voltage is 119, 120 or 121.

If the load is at the grid point and is at 120.0, then any source
under 120.0 will pull power and not source it., but the load as a
reistor will pull current no matter what voltage is on it. A resistor
can never geneate power. But a motor connected to a grid can pull
power if you load the shaft or it can push power if you hook an engine
to the shaft and drive it.

Mark

Especially since you answered your own questions in your response.

-------

"g" wrote in message ...

Well, I was just teasing him, did not really expect any answer.

Why would there be a local increase in the voltage?

The grid is filled with tapchangers and capacitors to adjust the voltage to
a constant level, loads on a complex grid can shift load continuously to
another place. A small PV source may increase the voltage up to the next
house and would never be noticed.

-------------------

"Mark" wrote in message
...

there is a VERY slight increase in local voltage.

If you want to push 5 kW back into the gird, the local voltage rises
by the amount of voltage drop in the wires leading to the grid with 5
kW flowing through them. Its the same amount as it drops when 5 kW
flows out.

For example, if the grid is 120.0 and your house is pulling 5 kW,
then the local voltage at your house may drop to 119.9.

If your house pushes 5 kW into the grid the local voltage at your
house may rise to 120.1.

The 5 kw is not wasted, the rest of the grid reduces its generation by
that 5 kW to keep the grid at 120.0.

Another analogy is tandem bikes. If the back person pushes harder,
the front person has to push less to go at the same speed.
For synchronous AC motors and generators this is really a good
analogy, they are all running at exactly the same speed and the PHASE
slips ahead or behind slightly depending on which way the power
flows. You can think of it as a bit of stretch in the bike chain one
way or the other.

A lot of the engineering of power systems goes into how the load is
shared among multiple sources.

But in any case, a 5 kW load or source is very small compared to the
overall power flow in the grid.

Mark

Perfect logic and based on real thinking.

Bonus points...select a vowel.
-----------------

"Smitty Two" wrote in message
news
In article ,

I've chewed this over a bit, and I still don't like it, and here are my
reasons:

1: Voltage sources in parallel do not push *against* one another.

2: If no voltage source can join the grid without being at a higher than
grid potential, then every contributing power station would have to be
at a higher potential than every other one, and that's impossible.

3: While voltage might *push*, it's the load that it said to *pull* the
current. If there's a demand, current will flow whether the supply
voltage is 119, 120 or 121.


Where is my thinking flawed?

Absolutely correct.

Two voltage sources in parallel are at the same voltage.
Two exact voltage in parallel can supply the same load and split the load
between them based on the impedance from source (including it's own internal
impedance) to the load in the loop formed.

Yes the trolls are only trying to wreck another group. Sad from some
mentally damaged types but it happens.

---------------------
"David Nebenzahl" wrote in message
. com...
It *sounds*--and I'm sure you'll correct me if I'm wrong--as if you're
agreeing with me, and with Smitty, and others when we say that it is
*not* required that the photovoltaic inverter supply a higher voltage in
order to transfer current to the grid. (I take this from the last
sentence in the next-to-last paragraph, where you say " ... will adapt
itself to the line voltage, whatever it may be".)

The arguments against this, with all the pseudo-science being thrown
around (most of it by the ones who are also slinging insults) are
getting quite tiresome here.


--

Sorry, totally incorrect assumption. I guess the real world isn't for you



Load current is shared depending on impedance of parallel source loops.

--------------------

"g" wrote in message ...
If you take the voltage drops into account, the voltage at the inverter
has to be higher than the voltage at the grid connection point.

This is a real world scenario.

Sorry, Your inconsideration, using all caps and messing with header info is
intolerable, m II, no spam, g

PLONK
-----------------------

"The Ghost in The Machine" wrote in message
...
DOESNT YOUR HUSBAND MAKE YOU HAPPY.....?

I SEE YOU ALSO HAVE A PERVERTED SEMEN FETISH, YOU DEVIANT!!

PLEASE LEAVE OUR USENET GROUPS AND PERSUE YOUR TWISTED FANCY IN SOME
DATING SERVICE FOR UNHAPPLIY WED PERSONS LIKE YOURSELF, OR TAKE IT
ELSEWHERE FELLER, WE'RE NOT IN THE MOOD FOR YOUR MANBOY CRAVING
SHENANIGANS.

PATECUM

On 18/04/2011 05:44, no spam wrote:
wrote:


Well, I was just teasing him, did not really expect any answer.

Pigs-arse you were "teasing". You were sucked in
by the GymmyBob troll.. another of a few hundred
of his 'victims'. Deservedly so on this occasion.. you
prove a clueless dolt.

Get yourself educated on "how to" in reading news, rube.
netscape.public.mozilla.general

Then go check out your 'victor' :-/

You apparently have spent a lot of time "checking out" people.
Well, it is your time, waste it as you see fit. Better you than me.

Your tone of language though is one that tell much more about you than
you understand. Maybe you and Mho can waste each others time checking
each other out. For all I know you are one and the same.

Hopefully you will be so busy name-calling each other that the rest of
us can forget about you.

On 4/18/2011 4:34 AM Jim Wilkins spake thus:

On Apr 17, 11:40 pm, David Nebenzahl wrote:

On 4/17/2011 7:19 PM Jim Wilkins spake thus:

...

It *sounds*--and I'm sure you'll correct me if I'm wrong--as if
you're agreeing with me, and with Smitty, and others when we say
that it is *not* required that the photovoltaic inverter supply a
higher voltage in order to transfer current to the grid. (I take
this from the last sentence in the next-to-last paragraph, where
you say " ... will adapt itself to the line voltage, whatever it
may be".)

The inverter output is higher -internally- by the V=IR drop between it
and the grid.

In this case I is the independent variable, the array's output, and V
is whatever it takes to make I pass through R to get to the grid
voltage.

OK, now we're getting somewhere.

At the risk of igniting another round of sniping here, how does that
work, exactly? I assume you're talking about the voltage drop between
the inverter and the point where it's tied to the external power lines
(= grid), correct? So since it can only "see" its own internal voltage,
how does the inverter even know what that voltage drop is? How does it
regulate its voltage so that it's equal to the grid voltage at the point
of connection?

Or is this somehow self-regulating, where the inverter simply "aims" at
what it calculates is the grid voltage, based on the current delivered
by the PV system, and the voltage self-stabilizes?

Gory details, please.


--
The current state of literacy in our advanced civilization:

yo
wassup
nuttin
wan2 hang
k
where
here
k
l8tr
by

- from Usenet (what's *that*?)

On Apr 18, 3:45*pm, David Nebenzahl wrote:
On 4/18/2011 4:34 AM Jim Wilkins spake thus:





On Apr 17, 11:40 pm, David Nebenzahl wrote:

On 4/17/2011 7:19 PM Jim Wilkins spake thus:

...

It *sounds*--and I'm sure you'll correct me if I'm wrong--as if
you're agreeing with me, and with Smitty, and others when we say
that it is *not* required that the photovoltaic inverter supply a
higher voltage in order to transfer current to the grid. (I take
this from the last sentence in the next-to-last paragraph, where
you say " ... will adapt itself to the line voltage, whatever it
may be".)

The inverter output is higher -internally- by the V=IR drop between it
and the grid.

In this case I is the independent variable, the array's output, and V
is whatever it takes to make I pass through R to get to the grid
voltage.

OK, now we're getting somewhere.

At the risk of igniting another round of sniping here, how does that
work, exactly? I assume you're talking about the voltage drop between
the inverter and the point where it's tied to the external power lines
(= grid), correct? So since it can only "see" its own internal voltage,
how does the inverter even know what that voltage drop is? How does it
regulate its voltage so that it's equal to the grid voltage at the point
of connection?

Or is this somehow self-regulating, where the inverter simply "aims" at
what it calculates is the grid voltage, based on the current delivered
by the PV system, and the voltage self-stabilizes?

Gory details, please.




Take a look at the simple circuit analysis I provided earlier today
that is
a few posts down in this thread. I drew a model of the situation we
have been discussing which is very similar to the example circuit
Wilkins provided earlier. And it shows how not only the internal
voltage
of the PV array must rise, but so too the voltage on the grid at the
point of connection. It all follows directly from Krichoff's Law.




--
The current state of literacy in our advanced civilization:

* *yo
* *wassup
* *nuttin
* *wan2 hang
* *k
* *where
* *here
* *k
* *l8tr
* *by

- from Usenet (what's *that*?)- Hide quoted text -

- Show quoted text -

On Apr 18, 3:45*pm, David Nebenzahl wrote:
On 4/18/2011 4:34 AM Jim Wilkins spake thus:





On Apr 17, 11:40 pm, David Nebenzahl wrote:

On 4/17/2011 7:19 PM Jim Wilkins spake thus:

...

It *sounds*--and I'm sure you'll correct me if I'm wrong--as if
you're agreeing with me, and with Smitty, and others when we say
that it is *not* required that the photovoltaic inverter supply a
higher voltage in order to transfer current to the grid. (I take
this from the last sentence in the next-to-last paragraph, where
you say " ... will adapt itself to the line voltage, whatever it
may be".)

The inverter output is higher -internally- by the V=IR drop between it
and the grid.

In this case I is the independent variable, the array's output, and V
is whatever it takes to make I pass through R to get to the grid
voltage.

OK, now we're getting somewhere.

At the risk of igniting another round of sniping here, how does that
work, exactly? I assume you're talking about the voltage drop between
the inverter and the point where it's tied to the external power lines
(= grid), correct? So since it can only "see" its own internal voltage,
how does the inverter even know what that voltage drop is? How does it
regulate its voltage so that it's equal to the grid voltage at the point
of connection?

Or is this somehow self-regulating, where the inverter simply "aims" at
what it calculates is the grid voltage, based on the current delivered
by the PV system, and the voltage self-stabilizes?

Gory details, please.


http://www.solarpanelsplus.com/solar...lar-Panels.pdf

On 4/18/2011 2:39 PM Bruce Richmond spake thus:

On Apr 18, 3:45 pm, David Nebenzahl wrote:

At the risk of igniting another round of sniping here, how does
that work, exactly? I assume you're talking about the voltage drop
between the inverter and the point where it's tied to the external
power lines (= grid), correct? So since it can only "see" its own
internal voltage, how does the inverter even know what that voltage
drop is? How does it regulate its voltage so that it's equal to the
grid voltage at the point of connection?

Or is this somehow self-regulating, where the inverter simply
"aims" at what it calculates is the grid voltage, based on the
current delivered by the PV system, and the voltage
self-stabilizes?

Gory details, please.

http://www.solarpanelsplus.com/solar...lar-Panels.pdf

Y'know, that's the *second* time you've offered that document as a
supposed answer to a question, and it doesn't contain any more relevant
information to what I asked than it did the first time. It is chock-full
of other interesting details, but it does *not* answer my question at
all. The most they have to say is that a DSP is used to sense the
line-side voltage and relay it to the intertie; however, they don't
explain just how this all works in the detail I was asking for.

I invite you to point out specific sections that answer my question, as
I have a copy of the PDF handy, if you think I'm mistaken.


--
The current state of literacy in our advanced civilization:

yo
wassup
nuttin
wan2 hang
k
where
here
k
l8tr
by

- from Usenet (what's *that*?)

On 4/18/2011 2:20 PM spake thus:

On Apr 18, 3:45 pm, David Nebenzahl wrote:

At the risk of igniting another round of sniping here, how does
that work, exactly? I assume you're talking about the voltage drop
between the inverter and the point where it's tied to the external
power lines (= grid), correct? So since it can only "see" its own
internal voltage, how does the inverter even know what that voltage
drop is? How does it regulate its voltage so that it's equal to the
grid voltage at the point of connection?

Or is this somehow self-regulating, where the inverter simply
"aims" at what it calculates is the grid voltage, based on the
current delivered by the PV system, and the voltage
self-stabilizes?

Gory details, please.

Take a look at the simple circuit analysis I provided earlier today
that is a few posts down in this thread. I drew a model of the
situation we have been discussing which is very similar to the
example circuit Wilkins provided earlier. And it shows how not only
the internal voltage of the PV array must rise, but so too the
voltage on the grid at the point of connection. It all follows
directly from Krichoff's Law.

The problem I have with that post is that the ASCII graphics you used
are all jumbled and I can't make sense of them (trouble with line
lengths, I think). Any chance you can redraw it in such a way that news
clients won't scramble it? (Maybe try drawing shorter lines with "hard
returns" at the end?)


--
The current state of literacy in our advanced civilization:

yo
wassup
nuttin
wan2 hang
k
where
here
k
l8tr
by

- from Usenet (what's *that*?)

On Tue, 19 Apr 2011 02:21:10 +1000, "Mho" wrote:

Sorry, totally incorrect assumption. I guess the real world isn't for you

You're wrong, 'g' is correct. You can't even figure out how to use a
newsreader.

Load current is shared depending on impedance of parallel source loops.

Word salad.

--------------------

"g" wrote in message ...
If you take the voltage drops into account, the voltage at the inverter
has to be higher than the voltage at the grid connection point.

This is a real world scenario.

On Apr 18, 12:37*pm, "Mho" wrote:
Sorry, Your inconsideration, using all caps and messing with header info *is
intolerable, m II, no spam, g

PLONK
-----------------------

"The Ghost in The Machine" *wrote in ...
DOESNT YOUR HUSBAND MAKE YOU HAPPY.....?

I SEE YOU ALSO HAVE A PERVERTED SEMEN FETISH, YOU DEVIANT!!

PLEASE LEAVE OUR USENET GROUPS AND PERSUE YOUR TWISTED FANCY IN SOME
DATING SERVICE FOR UNHAPPLIY WED PERSONS LIKE YOURSELF, OR TAKE IT
ELSEWHERE FELLER, WE'RE NOT IN THE MOOD FOR YOUR MANBOY CRAVING
SHENANIGANS.

PATECUM

RIGHT BACK ATCHA -YOU ARE NOT ALL THAT NICE OR CORRECT EITHER OHM.
YOU ARE JUST DEFENDING YOUR LITTLE TROLL FRIEND THERE.
NO HEADERS WERE HARMED IN THIS DISCUSSION.
PLONK!!!
PAT ECUM

On Mon, 18 Apr 2011 16:01:51 -0700, David Nebenzahl
wrote:

On 4/18/2011 2:20 PM spake thus:

On Apr 18, 3:45 pm, David Nebenzahl wrote:

At the risk of igniting another round of sniping here, how does
that work, exactly? I assume you're talking about the voltage drop
between the inverter and the point where it's tied to the external
power lines (= grid), correct? So since it can only "see" its own
internal voltage, how does the inverter even know what that voltage
drop is? How does it regulate its voltage so that it's equal to the
grid voltage at the point of connection?

Or is this somehow self-regulating, where the inverter simply
"aims" at what it calculates is the grid voltage, based on the
current delivered by the PV system, and the voltage
self-stabilizes?

Gory details, please.

Take a look at the simple circuit analysis I provided earlier today
that is a few posts down in this thread. I drew a model of the
situation we have been discussing which is very similar to the
example circuit Wilkins provided earlier. And it shows how not only
the internal voltage of the PV array must rise, but so too the
voltage on the grid at the point of connection. It all follows
directly from Krichoff's Law.

The problem I have with that post is that the ASCII graphics you used
are all jumbled and I can't make sense of them (trouble with line
lengths, I think). Any chance you can redraw it in such a way that news
clients won't scramble it? (Maybe try drawing shorter lines with "hard
returns" at the end?)

Make sure it's in a fixed space font.

On Apr 18, 10:13*pm, "Mho" wrote:
Adding another source lowers the net impedance of the supply to the load.

This is simple network theorem. Even ohm's law can tell you the voltage
requirements.

The voltage at the grid connection (assuming where Rg is) will not be the
same as the V2 source.

Well, duh! I think everyone here, on both sides of the discussion
acknowledge that.



In DC theorem what you are saying would be basically all true but in AC we
have waveform phase angle and waveform distortion.

Not just basically, it is ALL exactly true with the equations to back
it up.
As for the complications of AC, there wouldn't appear to be much
point in discussing that until there is agreement on what happens
with a simple DC distribution system voltage example.




As an extreme example: consider a PV co-gen that is 180 degrees out of phase
from the grid. Now we can have a 10 volt PV source hooked to a 240V grid and
still supply current from it.
--------------------

I guess I went too fast for you with the AC stuff.

The whole point is regarding AC connections and different rules apply. The
DC basics are mostly valid no matter how much you want to disagree with
something but still moot and established by the discussing people about 100
posts ago. Your ASCII schematic was nice.

I will let you disagree with yourself a little more for the next while.
----------------

wrote in message
...

On Apr 18, 10:13 pm, "Mho" wrote:
Adding another source lowers the net impedance of the supply to the load.

This is simple network theorem. Even ohm's law can tell you the voltage
requirements.

The voltage at the grid connection (assuming where Rg is) will not be the
same as the V2 source.

Well, duh! I think everyone here, on both sides of the discussion
acknowledge that.



In DC theorem what you are saying would be basically all true but in AC we
have waveform phase angle and waveform distortion.

Not just basically, it is ALL exactly true with the equations to back
it up.
As for the complications of AC, there wouldn't appear to be much
point in discussing that until there is agreement on what happens
with a simple DC distribution system voltage example.




As an extreme example: consider a PV co-gen that is 180 degrees out of
phase
from the grid. Now we can have a 10 volt PV source hooked to a 240V grid
and
still supply current from it.
--------------------

Or is this somehow self-regulating, where the inverter simply
"aims" at what it calculates is the grid voltage, based on the
current delivered by the PV system, and the voltage
self-stabilizes?

Gory details, please.


http://www.solarpanelsplus.com/solar...ters-Work-With
-Solar-Panels.pdf

Y'know, that's the *second* time you've offered that document as a
supposed answer to a question, and it doesn't contain any more relevant
information to what I asked than it did the first time. It is chock-full
of other interesting details, but it does *not* answer my question at
all. The most they have to say is that a DSP is used to sense the
line-side voltage and relay it to the intertie; however, they don't
explain just how this all works in the detail I was asking for.

I invite you to point out specific sections that answer my question, as
I have a copy of the PDF handy, if you think I'm mistaken.


David,

my suggestion to you is to google the term "current source". Most sources
you are familiar with like batteries and generators are more like voltage
sources. A current source is in a way the opposite concept and you need to
think about it for a while.) A grid tie inverter emulates a current
source. It puts out at its terminals (within limits) whatever voltage is
needed to cause the desired current to flow.

They all follow Ohms law I=E/R. With a voltage source, V is fixed and I
varies with R. With a current source, I is fixed and V varies with R.

In a normal grid tie situation, the amount the V has to vary is very small
probably 1 or 2 volts at the most. That is the detail of how it controls
the current. The voltage will rise or fall as required such that the
desired current flows.

You can Google the design of current sources for more detail.

Mark

In article , "MarkK"
wrote:

A grid tie inverter emulates a current
source.

Good lord. That's what all this is about? 9,000 rambling posts full of
arithmetic and gibberish and it all comes down to that? Why didn't you
speak up earlier? Well, maybe you did, I confess I've gotten bogged down
with all the long-windedness that's permeated the thread and I've
deleted a few posts without reading them.

Now I feel like we're getting somewhere, or at least, I might be. All
that talk of inverters putting out an extra volt to compensate for the
resistance of the wire from the house to the pole made no sense at all.
A current source, that's something I can comprehend.

On Apr 19, 1:06*am, Smitty Two wrote:
In article , "MarkK"
wrote:

A grid tie inverter emulates a current
source.

Good lord. That's what all this is about? 9,000 rambling posts full of
arithmetic and gibberish and it all comes down to that? Why didn't you
speak up earlier? Well, maybe you did, I confess I've gotten bogged down
with all the long-windedness that's permeated the thread and I've
deleted a few posts without reading them.

Now I feel like we're getting somewhere, or at least, I might be. All
that talk of inverters putting out an extra volt to compensate for the
resistance of the wire from the house to the pole made no sense at all.
A current source, that's something I can comprehend.

HEAVENS TO BETSY, WE ARE SO HAPPY FOR YOU SMITTY TWO TWO.
GOODNIGHT!:-/

PAT ECUM

On Apr 18, 6:56*pm, David Nebenzahl wrote:
On 4/18/2011 2:39 PM Bruce Richmond spake thus:





On Apr 18, 3:45 pm, David Nebenzahl wrote:

At the risk of igniting another round of sniping here, how does
that work, exactly? I assume you're talking about the voltage drop
between the inverter and the point where it's tied to the external
power lines (= grid), correct? So since it can only "see" its own
internal voltage, how does the inverter even know what that voltage
drop is? How does it regulate its voltage so that it's equal to the
grid voltage at the point of connection?

Or is this somehow self-regulating, where the inverter simply
"aims" at what it calculates is the grid voltage, based on the
current delivered by the PV system, and the voltage
self-stabilizes?

Gory details, please.

http://www.solarpanelsplus.com/solar...r-Inverters-Wo...

Y'know, that's the *second* time you've offered that document as a
supposed answer to a question, and it doesn't contain any more relevant
information to what I asked than it did the first time. It is chock-full
of other interesting details, but it does *not* answer my question at
all. The most they have to say is that a DSP is used to sense the
line-side voltage and relay it to the intertie; however, they don't
explain just how this all works in the detail I was asking for.

I invite you to point out specific sections that answer my question, as
I have a copy of the PDF handy, if you think I'm mistaken.

On pg 76 it mentions a DSP

http://en.wikipedia.org/wiki/Digital_signal_processor

It can take DC voltage and build a sin wave using PWM (Pulse Width
Modulation)

http://en.wikipedia.org/wiki/Pulse-width_modulation

As shown on pg 74 that is smoothed and fed into a transformer. A
feedback circuit measures the current flow and adjusts the voltage of
the constructed wave as needed. Not sure what you want here. If you
want the exact details about how each part works google is your
friend. 30 years ago I was working with drive panels for large
industrial DC motors that did all this to feed current back into the
lines when doing regenerative braking. When they want to slow down
they don't worry about sharing a load. They know there are loads out
there and they just pump the power into the line. At that time it was
all controlled using analog circuits.

On Apr 19, 1:06*am, Smitty Two wrote:
In article , "MarkK"
wrote:

A grid tie inverter emulates a current
source.

Good lord. That's what all this is about? 9,000 rambling posts full of
arithmetic and gibberish and it all comes down to that? Why didn't you
speak up earlier? Well, maybe you did, I confess I've gotten bogged down
with all the long-windedness that's permeated the thread and I've
deleted a few posts without reading them.

Now I feel like we're getting somewhere, or at least, I might be. All
that talk of inverters putting out an extra volt to compensate for the
resistance of the wire from the house to the pole made no sense at all.
A current source, that's something I can comprehend.

Google "Norton and Thevinin Equivalency" or "Norton Thevinin
Circuits".

You'll see that a resistive circuit can be modeled as either a current
source or a voltage source together with a resistor and that they are
interchangeable and equivalent in how they behave.

On 4/19/2011 12:33 PM Mho spake thus:

You need to change your "fixed spacing" font to one that is "fixed
spacing"

I can even read it perfectly in your reply.

Look, my display font IS monospaced. Like, duh.

It's still all garbled. Line wrapping and all that. Your news client
(Microsoft Windows Live Mail 15.4.3508.1109) probably behaves
differently from mine (Thunderbird).


--
The current state of literacy in our advanced civilization:

yo
wassup
nuttin
wan2 hang
k
where
here
k
l8tr
by

- from Usenet (what's *that*?)

On 4/18/2011 12:05 PM, Mho wrote:
Why would there be a local increase in the voltage?

The grid is filled with tapchangers and capacitors to adjust the voltage
to a constant level, loads on a complex grid can shift load continuously
to another place. A small PV source may increase the voltage up to the
next house and would never be noticed.


Like he said, if there is a change in the current flow there is a change
in the voltage drop across each component between you and 'the grid'.
The impedance of these components is small, but nevertheless it exists.

Besides, grid voltage regulation is not perfect. Those tap-changers you
mentioned have discrete steps and most have time-delays in them with a
dead-band around their set-point. These are designed so the thing
doesn't wear out constantly stepping up and down when the voltage
set-point is 'between' the tap settings.

daestrom
snip

On Apr 19, 4:56*pm, daestrom wrote:
...Those tap-changers you
mentioned have discrete steps and most have time-delays in them with a
dead-band around their set-point. *These are designed so the thing
doesn't wear out constantly stepping up and down when the voltage
set-point is 'between' the tap settings.

daestrom
snip

Would the contacts be the tungsten (heavy) cylindrical slugs sometimes
found below equipment-laden power poles?

jsw

On Tue, 19 Apr 2011 04:56:03 -0700 (PDT), "
wrote:

On Apr 19, 1:06*am, Smitty Two wrote:
In article , "MarkK"
wrote:

A grid tie inverter emulates a current
source.

Good lord. That's what all this is about? 9,000 rambling posts full of
arithmetic and gibberish and it all comes down to that? Why didn't you
speak up earlier? Well, maybe you did, I confess I've gotten bogged down
with all the long-windedness that's permeated the thread and I've
deleted a few posts without reading them.

Now I feel like we're getting somewhere, or at least, I might be. All
that talk of inverters putting out an extra volt to compensate for the
resistance of the wire from the house to the pole made no sense at all.
A current source, that's something I can comprehend.

Google "Norton and Thevinin Equivalency" or "Norton Thevinin
Circuits".

You'll see that a resistive circuit can be modeled as either a current
source or a voltage source together with a resistor and that they are
interchangeable and equivalent in how they behave.

Bingo! It doesn't matter which you model the inverter as, the physics doesn't
change.

On Apr 19, 6:49*pm, "
wrote:
On Tue, 19 Apr 2011 04:56:03 -0700 (PDT), "





wrote:
On Apr 19, 1:06 am, Smitty Two wrote:
In article , "MarkK"
wrote:

A grid tie inverter emulates a current
source.

Good lord. That's what all this is about? 9,000 rambling posts full of
arithmetic and gibberish and it all comes down to that? Why didn't you
speak up earlier? Well, maybe you did, I confess I've gotten bogged down
with all the long-windedness that's permeated the thread and I've
deleted a few posts without reading them.

Now I feel like we're getting somewhere, or at least, I might be. All
that talk of inverters putting out an extra volt to compensate for the
resistance of the wire from the house to the pole made no sense at all..
A current source, that's something I can comprehend.

Google "Norton and Thevinin Equivalency" or "Norton Thevinin
Circuits".

You'll see that a resistive circuit can be modeled as either a current
source or a voltage source together with a resistor and that they are
interchangeable and equivalent in how they behave.

Bingo! *It doesn't matter which you model the inverter as, the physics doesn't
change.- Hide quoted text -

- Show quoted text -

Yes, we'e on the same page. They are interchangeable, but I think
Mark had a good idea in bringing up the idea of the current source,
as conceptually it's a bit easier to understand. It appears to have
got Smitty at least partly convinced.

Jim Wilkins wrote:
On Apr 19, 4:56*pm, daestrom wrote:
...Those tap-changers you
mentioned have discrete steps and most have time-delays in them with a
dead-band around their set-point. *These are designed so the thing
doesn't wear out constantly stepping up and down when the voltage
set-point is 'between' the tap settings.

daestrom
snip

Would the contacts be the tungsten (heavy) cylindrical slugs sometimes
found below equipment-laden power poles?

jsw

... twould be a strange grid/retic system indeed were
tap change contacts found in the environment.
Then again I am not surprised at anything uttered
from those who feed the Gymmy Bob troll.

GB will be very busy searching his digests of
"Popular Mechanics" for the term "dead-band"
just to be sure it isn't an old Bob Marley joke:-

"Gymy Bob" /3auj4kc
"John P. Bengi" /3zgxjxa
"Solar Flare" /42ytgkq
"Pizzza Girl" /3p979nm
"Janice" /3bctgwr
"Joesepi" /3qkwmxr

... mind how you go. Don't want you
bleeding all over the place:-D

On 4/19/2011 17:28 PM, Jim Wilkins wrote:
On Apr 19, 4:56 pm, wrote:
...Those tap-changers you
mentioned have discrete steps and most have time-delays in them with a
dead-band around their set-point. These are designed so the thing
doesn't wear out constantly stepping up and down when the voltage
set-point is 'between' the tap settings.

daestrom
snip

Would the contacts be the tungsten (heavy) cylindrical slugs sometimes
found below equipment-laden power poles?

jsw

The few tap-changers I've seen 'up close and personnel' are in
sub-stations, not pole-mounted. The contacts are in oil-bath and
arranged such that they don't open under appreciable current (multiple
contacts, a center-tapped inductor and ingenious mechanism).

daestrom