I saw a presentation last night put on by our local POCO, (LIPA) on the chain of events leading up to the Blackout on Long Island (NY) and the challenges faced in getting everything back online. The speaker was the person in charge of keeping all of the High Voltage lines in operation. He went on to talk about what he says was the worst (and most educational) 26 hrs of his life.
I don't know a lot about this stuff, but what he said sounded logical to me and some of the problems mentioned in getting things back on line also made sense and I think we may take these guys for granted a bit much sometimes. It sounds like a whole lot more than just flipping switches back on. My hat's off to anyone involved in bringing things back that might be reading this.
I used to work at a plant that had three services all pulling just under a gigawatt (1,000,000,000w). The POCO had an automatic cut-out if it went over, which I remember happening at least once. This was caused by large shorts on our end.
-production staff would go to 'general coffee', and the emergency generator would hopefully start
-everyone would shut up on the radio, except the electricians
-the electrical super or plant engineer would assign tasks to 3-14 electricians, depending on the time of day (24/7 production, $20,000/min downtime)
-we would then start isolating sections of the plant
-the power would return automatically
Start panicking, but remain calm and follow instructions.
-we had to bring everything back online in an order that both avoided inrush trips, as well as the most cost effective order for production
-the short would usually show up at this time, and trip us out again.
Remember which breaker you were turning on when the lights went out the second time.
Power failures from outside would have a similar procedure. The plant has been expanding since construction in the '60s-'70s, and the staff keeps tuning the procedure. My contribution was putting an emergency light in the electrical shop.
Some of the problems discussed had to do with getting the different type of generators restarted, Steamline ruptures, purging and re-energizing some liquid-filled power lines (?) stabilizing frequency as things were started up and loads were added.
It seemed like they had to be very careful about what they did until they were re-connected to the main grids, because unbalances could easily cause frequency change and automatic load-shedding or over/under frequency relays to drop out and shut things down again.
He used an analogy to describe how important the stability of being connected to the main grid that I don't know how accurate it is but I thought was great. It was something like this:
Picture the load as being a child jumping up and down on a bed. Picture the generating plants across the country all connected together as a 100 pound weight. When the child jumps up and down on the bed it doesn't have much effect on the weight. Now picture unconnected generating plants as 100 one pound weights. Each time the child jumps on the bed some will fall off until all are gone.