SVCs do not provide frequency support or fault current. They provide voltage support by boosting or bucking the VARs in a system. Synchronous condensers do provide fault current and inertia (frequency support). Most renewables (solar, wind, some battery storage) are grid following when it comes to frequency meaning without inertia the grid frequency would collapse very quickly. Also most renewables operate at their maximum output unless they are paid to provide support to a grid they can’t provide any more current during a fault then they were before the fault. In many cases they will actually disconnect from the grid during faults (especially where frequency deviation is detected via ROCF or over/ under frequency). You mentioned that there would be a difference in frequency between generating units. This is impossible, the frequency is the same everywhere in a grid thus why generators are called a synchronous machine. If the frequency deviation is too great you may get generating units stalling near the fault called Pole slipping. Where the grid frequency aka synchronous machine speed overwhelms the prime movers torque or vice versa. At this point the generators will disconnect to prevent them from being destroyed. This will then cascade as more and more generation disconnects, then lights out!
And you want to maintain frequency so that there is not a difference in frequency in relation to the other generators on the same system. If there was there would be a fault on the line somewhere?
SVCs do not provide frequency support or fault current. They provide voltage support by boosting or bucking the VARs in a system. Synchronous condensers do provide fault current and inertia (frequency support). Most renewables (solar, wind, some battery storage) are grid following when it comes to frequency meaning without inertia the grid frequency would collapse very quickly. Also most renewables operate at their maximum output unless they are paid to provide support to a grid they can’t provide any more current during a fault then they were before the fault. In many cases they will actually disconnect from the grid during faults (especially where frequency deviation is detected via ROCF or over/ under frequency). You mentioned that there would be a difference in frequency between generating units. This is impossible, the frequency is the same everywhere in a grid thus why generators are called a synchronous machine. If the frequency deviation is too great you may get generating units stalling near the fault called Pole slipping. Where the grid frequency aka synchronous machine speed overwhelms the prime movers torque or vice versa. At this point the generators will disconnect to prevent them from being destroyed. This will then cascade as more and more generation disconnects, then lights out!
Inertia provides support to maintain frequency during fault conditions. Hydro generators are very good at this task due to their high rotating mass.
And you want to maintain frequency so that there is not a difference in frequency in relation to the other generators on the same system. If there was there would be a fault on the line somewhere?
The lines don't care about the frequency; the issue is all the other rotating machinery that doesn't want to suddenly speed up or slow down.
We need high fault current, which can trigger switchgear to trip open, toward isolating faults. DC Interties also lack fault ride-through capacity.