paralelism or synchronism?

[odlanor]

after the blackout of a Large Grid, the restoration of the system begins by SE-230kV substation;
As a start, SE-230 is found to have two independent busbas 230kV energized;

The A-busbar is connected to A-load a priority that is being supplied by the A-power plant via a 110km -230kV line.

B-busBar is connected to high-priority B-load which is being supplied with the B-power plant through a 10km-230kV line.

system B defines the frequency of Large Grid. It is necessary to connect the A-busbar with B-busbar to continue the restoration of Large Grid.
You must install a synchronization system in the SE-230kV;
question:
1 - that is parallel or synchronism of system A to B?
2 - What would the procedure for the synchronization (or parallelism) knowing that the A-powerplant is 100km away.

 

[inpran]

Its synchronisation. A and B bus-bars are at different frequencies, considering that they are being fed from different sources and catering to different loads and hence connecting then would involve syncronising. Had the both buses been fed from the same source and had a common load end, then it would have been parallel.
As for the procedure, generally there will be a synchro check relay in the Bus-coupler panel that will enable bus-coupler breaker's closing when the synchronising conditions are met. I'm not sure whether it matters or not if you have a differently loaded bus at the time of synchronising.

 

[odlanor]

inpran,
I am not so sure. This is not unload generator. There are two independent island system operating in 60Hz. Phase angle of frequency are differents.
This is a big difference:
- synchronism
For manual synchronization I have to install synchronoscope and synchrocheck relay at synchronization panel. There will be remote comunication between operators of SE-230kV and A-power plant A.
-paralelism
For manual paralelism I have to install synchrocheck relay at synchronization panel. Operator at SE230kV close circuitbreaker meanwhile operator of A-power plant A will change regulation of power slowly up to synchrocheck relay operate at close circuit of CB.

 

[waross]

The paradox is that to synchronize frequencies the frequencies must be unequal. If the frequencies differ by only 0.1 Hz, (60:60.1 Hz or 50:50.1 Hz) there will be a phase angle match every 10 seconds. That should give an easy synchronization.
If the frequencies are exactly equal but more than about 5 deg. displaced they will never come into synchronization.
This is a window of +5 deg. to -5 deg. or 10 Deg. compared to 360 Deg, that is one chance in 36 that equal frequencies will be able to synchronize.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[odlanor]

We use 0.2 Hz, (60:60.2 Hz ) there will be a phase angle match every 5 seconds.
We can not permit frequencies exactly equal but more than about 5 deg. displaced they will never come into synchronization.If you change frequency A-power plant from 60.1 to 59.9 Hz you can get mismatch.
I guess some transmission substation use up to 30 degree to close ring system.