I can't give you an honest answer. I know that the system is, and has been hardened against the likes of lightning and such for decades, but that isn't the same as an EMP. Upgrades have been made, particularly to control circuitry in substations which would likely be the most vulnerable.
I think (my opinion) that the biggest vulnerability would be the CPU-based equipment, probably communications stuff also. Manual operation would be the alternative, providing that the field equipment is operational.
A lot of older electromechanical control devices have been upgraded to CPU-based over the last 25-30 years and I'm not privy to the resilience of that equipment to EMP type situations. It is something that, for the benefit of this board, I shall look into.
It is definitely on the industry radar, and we are working on it, but I am not in a position to know just where we stand on that. A lot of moves have been made to build in more redundancy in the transmission grid, which is prudent anyway, but the primary thing is to make something like an EMP a more local issue rather than system-wide.
The local grid is city owned with gas powered generators and a little hydro.
10-12 years ago, Qx wrote the city about EMP and received a very idiotic reply that the USA military would take care of us that there was nothing to worry about. He was so disgusted with the stupidity of the response he just gave up. He has thought of trying again, recently since it has been more in the news. And, there have been 2 Congressional studies trying to sound the alarm.
It has appeared that the PTB have deliberately neglected upgrading the system.