Continuing this thread from here.
Sorry about not getting back sooner on this thread.
Laura, you are correct about the greater demand that is on the grid today, as evidenced by the CA brownouts and blackouts a few years back. It is manageable - all in controlling the sequence of giving back power. The grid is set to run at exactly 60 Hz (cycles per second), and the entire North American power grid is synchronized to that frequency. There is a “jumper” system at the Mississippi that lets power across and resynchronizes to the Eastern and Western US grid.
AC (Alternating current) power generation is totally an on-demand situation. It supplies exactly the power demanded at 60 Hz. A generator in Maine will be in synch with a generator in Florida because the grid actually drives the generators at that speed. If load is too high the frequency drops under 60 Hz, and the safety disconnects kick out until the frequency returns to 60. Like-wise, the generators have controls to reduce power if they start to over-speed when load is lost, right up to the point of tripping off-line to prevent damage (fail-safe).
One of the hardest jobs in power generation was synchronizing a unit coming on line to the rest of the grid in pre-computerized days. It was a skill much like landing an airplane, to be at just the right speed and phase at the right moment when the big switches connected. In a few cases, the controllers missed with “spectacular” results, including a hole in a main transformer you could have driven a VW through in I saw at one plant.
To restart the system the grid is now designed to disconnect every one if the system goes off line beyond the point of recovery. That saves the equipment for restarting things – “fail-safe” again.
The Black Start rule is no one gets power until enough plants are on line to handle the load they are going to need to take - except another plant. It takes a lot of power to start a big power plant, be it gas, coal, or nuclear. Even hydro units need some power to run valve controls on start up. Most have their own emergency generators to supply a portion of their start up power. The best have an incremental start-up power system - that is the plant has multiple generators that increasingly give the next generator the power to start.
One specific plant I worked, LV Sutton in NC, had a 454 CID Chevy engine tied to a generator that it used to start a big gas turbine (jet engine) generator, that in turn was used to start the big coal burner units, that would then feed the next power station miles away to let it start. If the battery on the Chevy was dead, in theory we could us jumper cables to start it (sorry, some “blue collar comedy”).
Once a few plants were back up, the distribution center then would categorize the power starting to be fed to essential services. These are usually core utilities - like water and sewage plants - and life-safety facilities - like hospitals and police and fire 911 dispatch centers, telephone/internet switch centers and now cell towers. Next would come plants like fuel depots and refineries because of the safety and long restart times in many of those plants and their need for critical infrastructure support.
Next are large population centers and commerce areas, then the suburban sites, on down. It stops at the sub-station level, and that is how they control the power load. If too many washers and AC units and such come on at once, the sub-station will kick back off line. Until the imbalance is resolved, that area will stay unpowered. At that point the idea would be to have media (battery radioes) request people turn off appliances until the power is restored. (In the longer version of “The Stand” Stephen King had “cut-off crews” doing this so they could turn the power back on once the Bolder, CO power station was working. He really got that part right.)
It takes between hours and days depending on the damage that happened when things went down to “Black Start” a grid. But if an adjacent grid is working, then the plants “borrow” power to speed things up and the systems can reduce the time a lot.
I’ll only touch on something here because it will take a lot more detail than I can stay awake for tonight, but nuclear plants are a problem and a blessing in this situation.
The problem is that a nuke MUST have power, even if it is shut down, because reactors do not just cool off in a few hours. They take weeks to decay off the tremendous heat in a running core. And even then, the used fuel stored in the plants in what are called “spent fuel pools” has to be cooled and the reactor buildings themselves have to maintain negative air pressure to prevent chances of releasing radioactive gasses. True that the levels of radioactivity are not likely to be dangerous if the air handlers go off a few hours, but a few days would be different.
So all nukes have tremendous auxiliary power generators, big enough to run small towns, in duplicate, to be sure that they can maintain themselves for days or weeks. But at some point in a matter of 2 to 4 weeks, these generators will require more fuel, so that is why the “Black Start” requires getting refineries back into operation.
The blessing is that once a nuke is back on line, it can run for as much as a year without refueling, giving time to get the other plants repaired and get a lot of recovery work done. They also have some of the largest generators, meaning that nukes will hold more of the backbone of recovery power by running at near 100% capacity while other plans may run low on coal or gas until re-supplied by mines, refineries, or wells.
The best case for survival would be to be in an area with a nuke station and several fossil plants and a few hydro plants available to rebalance the load as quickly as possible. I’ll avoid the nuclear / no nuclear debate for now and just say that at our present technology having them is better than not having them to restart or even prevent the grid going off line. Having alternatives in the future would be even better. I have kids, and I want them to have safe power if we live through a pandemic.
I hope someone else will chime in on the Internet side. I know just enough about the telephone and Internet fiber-optic backbone to say it is made in a similar “fail-safe” fashion, but not in the detail I know the power grid system.
TRay75 - Thank you very much for this description. I allows me to make sense of the grid regarding a fuel shortage due to some kind of an event.
Thanks for the rundown TRay but can I just point out that it’s very well documented by now that the famous Californis blackouts and brownouts of a few years ago were artificially created by Enron
Thanks Tray for your knowledge. I have a friend at the phone company - I am going to grill him on their plans, etc. Maybe I cna get him to post as well.
lauraB - You are welcome. I’d like to hear more from the telco/internet folks about their system restart contengencies.
gw_doc - Enron cause a part off the CA blackouts, but after a point it was beyond even their control. Remember the “on-demand” aspects of power distribution. When Enron could not/did not get enough extra power capacity from the neighboring utilities, the other regional grids popped the disconnects and said “You’re on your own!” because to hang on and try to keep CA burning would have reduced frequency on the entire grid west of the Mississippi.EVERYONE would have gone dark. So in a way, even in light of Enron’s greed, the system proved that it worked by kicking them off line. That didn’t help the folks with no power, but it kept millions of others running.
(I personally think the Enron execs are in a class that rank with some of the lowest scum in history and I would never let them out of prison becasue their acts of greed caused deaths during those blackouts.)
I just hope your jaded view of their acts do not taint respect for the efforts the people working those power plants and distribution systems deserve. It is dangerous, hot, sometimes dirty work with something that will kill you if you make a mistake around a live steam or electric line. Most people working those jobs understand the responsibility of doing the job right and keeping power on as long as, to as many people as, possible. I know even if TSHTF some will work despite the risk because to stop will increase the death and suffering of their own families and friends.
Well, I just got back on after alsmot 3 days without DSL service. A main feeder was struck by lightning in my area. If it takes 3 days with the full complement of personnel, then just imagine what might happen in the event of a normal spring lightning storm with 1/3 or more of the folks out, and maybe no spare parts available when needed
Exactly the problem there. Eccles. I hopw we hear from someone on the Internet and telco side soon.
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