The whole point of the grid is that it is effectively one giant electrical machine, physically. It isn't possible to target your local generations n any more than it's possible to target a particular generator three towns over.

In any case, a 4.5gw load imbalance from moment to moment is not a difficult problem to solve. This is why all utilities are required to have 'spinning reserve' available to serve new load at very short notice. In the meantime the grid would just drop frequency very slightly (like 0.1 hz would be an enormous instantaneous deviation)