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Feeding solar power back into municipal grid: Issues and finger-pointing - Page 31

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Posted by no spam on April 23, 2011, 11:14 am
 

    [ghost-0-busted]


    /YOU\

... mind your tone of voice, chum.
I might just be one of those Usenet
"tough guys" you dream you
could maybe be, one day.

for now..?

GFYB



Posted by Mho on April 18, 2011, 4:02 pm
 
Especially since you answered your own questions in your response.

-------


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


Posted by Mark on April 17, 2011, 8:27 pm
 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









Posted by MarkK on April 17, 2011, 11:39 pm
 test


Posted by Mho on April 18, 2011, 4:05 pm
 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








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