Jetlagged,
On B747 classic and DC10, it is the load controlles that controls the freq by speeding up or slowing down the csd.
Blacksheep,
You said that the GCU/loadcontollers keep the gen freq´s syncronised. As I understand it, once the generators are conected in parellel they will always be syncronised, but the generator which phase comes ´first` will take the load.
Brgds
Doc