Is it difficult to join two modern power grids? [closed]

Question

I understand the voltage, frequency, phase, and maybe power quality of each grid must all be compatible at the moment of linking, and that each grid is a complex beast that's difficult to influence. So in the past, it could be very difficult to align all these variables at once.

How much has modern technology improved this? For example, atomic or GPS clocks should allow each grid to keep its frequency and phase locked to a common standard... at least in theory?

If we wanted a resilient grid design where a fragmented grid could start undamaged parts of itself independently, then link back together automatically as soon as faults were cleared - how close are we to having the technologies to do this, and how much restriction or expense would it add?

I'm also interested in near-future (but not science fiction) speculative designs, like putting large batteries in the grid fragments with grid-forming inverters that could drag the fragments into mutual compatibility.

Answer 1

It's a lot simpler than that, because grid parameters depend on each other.

Frequency is just the derivative of phase, so if the phase matches, so does frequency.

When you connect two grid points, the voltage difference between them determines how much power is transferred.

So you basically just adjust the frequency (by tuning generator output) until it is within .1 Hz, wait for the phase to be roughly the same, connect the grids and let them balance each other out.

After the connection has been made, one side will be leading a bit, which causes power to be transferred to the other side, where it takes load off the generators, causing them to speed up, increasing the frequency and by this, the phase. After a while, that reaches an equilibrium state, and you have a single grid.

In principle, we can automate this today. In practice, you still want grid operators, so that automation doesn't save much.