Re: Explode is not interesting
By "grid" you mean "tiny tiny section of the grid hanging off your local pole-mounted transformer"
No, I think he does mean the NATIONAL grid - and yes it's quite feasible to cause some serious disruption to it.
... the UK grid (and other developed countries' grids) are segmented to prevent cascading failures knocking down large chunks of the network simultaneously.
Actually, the UK grid is a single network - the North American grid is segmented by a few DC links, partly for stability reasons (it's a lot harder controlling a single grid of that size than one the size of the UK), and partly because for some long distance lines it's more efficient (less losses) to use DC.
We did have a national outage in the UK back in the 40s IIRC (or could have been later than that, can't find any references online). I recall my late father telling me about it, and how they found that there was a flaw in just about every power station design - an assumption that they would always have grid power during startup !
Each power station was designed on the assumption of there being grid power available for running all the machinery etc needed to run the power station. When the whole grid went dark, they found a catch 22 situation of not having the power to start up the power stations to generate power. I assume there was some carefully managed switching done to get some bits of the grid live and so allow the main stations to be started up. After that, they had a program of retrofitting gas turbine generators at most power stations to give them a black start capability - and they also came in useful for fast reacting peak lopping (ie coping with the peak when people go and switch the kettles on during the ad breaks on telly.) But I digress ...
As an AC has mentioned, we've had relatively recent experience with loss of significant generating capacity - have a read of this report.
The flip side is, what happens if someone can hack the control system and cause a massive disconnection of loads - perhaps at a peak time like the 6-7pm teatime slot on a cold winters evening, or thinking a bit more, it might be more effective if you can do it when they are already at a point of having to dial back the big plant at times of low demand. There's scope for some modelling there methinks ...
Answer, if you can drop a few GW off the grid, both voltage and frequency are going to go up VERY fast. That's probably going to cause some generating capacity to trip automatically* - that alone is going to cause some chaos. Then, when some of the big generators have tripped - turn all the loads back on. You've not got something similar to the 2008 incident above - but with some generating capacity tripped out and probably taking some time to get back into operational state. Rince and repeat a few times, I think you'll find it has "quite an impact" on the National Grid - and yes, I do think there is potential for significant blackouts (though probably not a complete national one.
* Hint - what do you think happens in a nuclear power station if it's running at full load, and it's generators trip out on over-voltage/frequency ? Well that's one hell of a kettle, and there's going to be an emergency shutdown on the nuclear side - there's no safety risk as there should still be power for all the safety and cooling systems to continue working as normal while it cools down. I strongly suspect that if the grid calls up 10 minutes later and asks for full output, they won't get an "OK, be on in the next few seconds" answer. They can probably get a significant output going quite quickly - but it takes time to ramp up the thermal output of the reactor so full power will take a while.
Similarly, in a coal plant, they'll shut down the coal feed immediately - putting the fires out. I don't know if they have any minimum time before they can attempt a relight - anyone have any inside knowledge on that ?