Electrical Engineering - Generator Grid Synchronization

Author

Generator Grid Synchronization - Distributed Line, Dedicated Line

lekosmoth@yahoo.com

2007-03-24, 9:25 am

If you are synchronizing a generator with a substation (grid). Do you
need a dedicated line from the generator to the grid - meaning all
generated power is supplied directly to the grid? Or is it possible
to distribute power along the way and connect to the grid?

If both the methods work. How would we synchronize generator and grid
on the non-dedicated line? What are the advantages and disadvantages
for both the techniques, assuming both work? What would we need other
than a synchro scope?

Thanks,
LS

Don Kelly

2007-03-26, 3:25 am

<lekosmoth@yahoo.com> wrote in message
news:1174743395.093658.298580@p15g2000hsd.googlegroups.com...
> If you are synchronizing a generator with a substation (grid). Do you
> need a dedicated line from the generator to the grid - meaning all
> generated power is supplied directly to the grid? Or is it possible
> to distribute power along the way and connect to the grid?
>
> If both the methods work. How would we synchronize generator and grid
> on the non-dedicated line? What are the advantages and disadvantages
> for both the techniques, assuming both work? What would we need other
> than a synchro scope?
>
> Thanks,
> LS

There is actually no difference
You have, at the point of synchronism, i.e. at the switch between the
incoming generator and the grid, a case where the whole of the grid- all
generators, loads and lines - appears as a Thevenin source on one side of
the switch. This presents a voltage and frequency. On the other side of the
switch there is the generator-or even another grid-also a Thevenin
source-which presents a voltage and frequency (I am ignoring phase rotation
in polyphase machines as this is, presumably hard wired to be correct).
Synchronisation simply involves matching the generator voltage -both phase
angle and magnitude- so that they are the same as the system voltage
magnitude and phase (matching phase implies matching frequency as one can't
match phase if frequency differs). Then close the switch. If done perfectly,
there will be no current flowing from the incoming machine to the grid. Then
one can try to raise speed a bit to pick up real power and try to raise
voltage to pick up reactive power.

If the incoming machine is supplying load and the switch is beyond this
load - at the grid connection- then the matching should still be at the
location of the switch- where the incoming and existing grid meet- this can
mean controlling a remote generator or even an incoming grid. This is a bit
more cumbersome than handling a single unloaded incoming generator (which is
the usual condition) but the basic information and control is the same-
match voltage and phase -A sychroscope simply shows the phase difference
when frequency differences are low. A method of detecting voltage magnitude
differences is also needed. A voltmeter will do.
- --

Don Kelly dhky@shawcross.ca
remove the X to answer
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