The terminology seems to be somewhat in flux. If an inverter based resource has the right software and control scheme setup, it can mimick either inertia or pr

The terminology seems to be somewhat in flux. If an inverter based resource has the right software and control scheme setup, it can mimick either inertia or primary frequency reserve. Although I think they're generally calling it all FFR (fast frequency response) now anyway. When a frequency event occurs, the rotating masses of conventional generation arrests the decline in frequency for a very short amount of time (this is caused by inertia), and then the control schemes of generators respond to assist with fully stopping the decline and some degree of recovery (PFR or primary frequency response). After that, your secondary reserves of (regulation) help take it back up and then (spinning reserves) until frequency is back at nominal. So, yeah FFR can be better than the conventional approach of inertia + PFR. Everything has to be configured properly (not any different than conventional resources, except FFR is still pretty new).