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Do power substations have automatic voltage regulation equipment?

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Posted by BobG on May 11, 2010, 9:19 pm
 
Just wondering how 'automatic' the load regulation is. Substation
feeds neighborhood... everyone comes home and turns on the stove and
air conditioner. Substation tries to step up the volts, which I
suppose tries to pull more from the primaries. Now lets say everyone
in this neighborhood gets a couple thou watts of PV on their roofs,
and on a sunny day, the whole subdivision might be a net producer,
which it seems to me would try to raise the volts on the hi voltage
feeders, but I was wondering what happens when a cloud drifts over
this subdivision... in seconds many KW would start flowing out instead
of in, which would start pulling down the feeders. Do the voltage
regulators work in a couple of cycles? Or seconds? Or??

Posted by Josepi on May 11, 2010, 9:36 pm
 
The units I have experience with responded in 20-30 seconds for the first
tap change and depending on the age, within a few seconds for each
successive tapchange. The older units waited the same 20-30 seconds each
time. Each tap was 5/8 to 3/4 of a percent of the system voltage.

Larger stations were outfitted with voltage regulation (230kV to 28kV) and
the lower voltages were typically not (28kV to 8kV). In the rural with long
lines there were some isolated poletop tapchangers on poles with similar
timings.

Backfeeding would become a problem as the voltage on the PV side would be
seens as high and the tapchanger woul go the wrong way. Advance CPU units
have current direction sensing to prevent this and grid-tie units are not
supposed to feed when the grid is down.

Different utilities allow more or less fluctuation in the voltages. As long
as your residence gets 120vac +/- 10%, to the panel, the legal requirements
are satisfied.



Just wondering how 'automatic' the load regulation is. Substation
feeds neighborhood... everyone comes home and turns on the stove and
air conditioner. Substation tries to step up the volts, which I
suppose tries to pull more from the primaries. Now lets say everyone
in this neighborhood gets a couple thou watts of PV on their roofs,
and on a sunny day, the whole subdivision might be a net producer,
which it seems to me would try to raise the volts on the hi voltage
feeders, but I was wondering what happens when a cloud drifts over
this subdivision... in seconds many KW would start flowing out instead
of in, which would start pulling down the feeders. Do the voltage
regulators work in a couple of cycles? Or seconds? Or??



Posted by m II on May 12, 2010, 4:40 am
 Josepi wrote:


Gymmie, Gymmie...the pile keeps getting deeper and deeper.

Two thousand watts produced per household in one area would have NO
effect whatever on the grid line voltage. The community in which this
power would be produced would use it all up. 2KW on a 240 volt house
feed is about 8 amperes. The ratio of the sum of all the dryers, ranges,
lighting and car block heaters going compared to 8 lousy amperes is
pretty small.

Now, it does mean the grid would supply a little bit less of the total,
but nowhere near enough of a drop in current to make the line voltage
rise to ANY noticeable degree.

I've been looking at your past posts and notice you were a child
medicine expert before becoming a transformer expert. Giving mood
altering tranquilizers to children is disgusting. Remember that?

Now, you've been a Transformer Design Engineer for over twenty years.
You told us that just before you said a fifty Hertz transformer needs
twice the core size of a sixty Hertz version.

Give it up, fraud....and please spare me the oh so predictable attacks
by one of your other five newsgroup personas.




mike

Posted by m II on May 28, 2010, 1:59 am
 

What are you some kind of child? You sure act like one

--

mike


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