[neltnerb]

Nope! They're connected in triangles all the time. I was stuck on this phase synchronization for a while, but really it's just the local phase lead or lag that is required.

Think of the phase as a distributed signal that indicates the current state of the local system taking into account all connected generators. It's weird but true!

[gpvos]

Can you elaborate? It is still unclear to me.

[neltnerb]

I may be explaining it wrong, but here is a reference, particularly 22.8:

https://www.scribd.com/doc/118169687/Network-Protection-Auto...

This makes it sound more complex than what I learned when I last tried to figure it out =)

They seem to be describing that where two grids meet they go through a synchronizer that disconnects one or the other if they aren't in sync, so implies manually disconnections throughout the network as needed locally.