What happens to the power grid if we loose 40% of it all at once?????????????????????????

-- FLAME AWAY (blehman202@aol.com), November 09, 1999

Answers

If 40% of the generating capacity fails, the "net" as a distribution system, must shed 40% load real fast to hold together. 40% in the dark is either "local" (remember Bennett!), or by rotating blackouts. Even though rotating blackouts make more sense, I doubt that this can be done technically or administatively. I cannot imagine a decision by anyone to put a major city into the dark for a few hours (the jerks at NERC?). Therefore the grid may exist in pieces, with much switcheroo going on, resulting in "dirty power". It is a matter of definition whether that still is a viable distribution "grid". All stands or falls with power in January!

-- Wf (notcookbut_edguess@guess.com), November 09, 1999.

I'm in a town that has it's own power and water company. I was wondering if we could just disconnect from the grid... (bye, bye.)

-- Mara (MaraWayne@aol.com), November 09, 1999.

Top demand is in summer with all the AC going. I would think that 40% in winter may be doable. But I guess it depends on where the failure is, and wheather the rest of the "local grid" can make up for it. A bunch of failures in the warm southeast won't matter much, as far as heat goes. But a bunch of failures in the cold northeast (my neck of the woods), where the "local grid" can't keep up, well, let's just say better safe than sorry...

Tick... Tock... <:00=

-- Sysman (y2kboard@yahoo.com), November 09, 1999.

MARA-- Let's hope your companies are up to snuff.

beej

-- beej (beej@ppbbs.com), November 09, 1999.

Mara, Technically, the answer is probably yes - legally, due to distribution contracts, it would almost undoubtedly be no.

On the technical side, the grid serves small power generators as a buffer against changing demand. Power delivery in a small area from one producer is seldom as clean or stable as that from a large grid.

On the legal or management side, if/when the power goes off, no one knows for how long it will be off, so initially there would be little to no thought of breaking distribution contracts. After a few weeks(???), the management *might* be more disposed to relieve the suffering around them by isolating and providing power locally. But who are the owners and where are their loyalties? You could go to the plant and ask. ;-)

Joe

-- Joe (paraflyr@cybernet1.com), November 10, 1999.

WF, you need to make sure you do not confuse capacity with load. It is when capacity drops below load that there are problems (blackouts, brownouts, rationing), but there is usually excess capacity. Here in the northeast, we have been told by the New England grid operator that we will have twice the capacity we really need at rollover. Assuming that is true (I have some problems with his assertion), then a 40% drop in capacity would be manageable.

-- Brooks (brooksbie@hotmail.com), November 10, 1999.

Very, very hard to say - because not only is the loss of capacity postulated (by your question) but the way it is lost is left to the imagination.

Remeber, everything anybody is predicting - including 40% loss like your question - is a guess, followed by assumption by the people answering, based on their assumptions of what might happen afterwards - all compounded by the uncertainity of "problems" INSIDE the system.

So even if we predict the response correctly, we can only make the predictions based on assumptions about how things might (or might not) work after any given problem occurs.

So lets assume "best case:" There will be less load than max: compare winter holiday weekend with many businesses shutdown to summer time with all AC running, all industrial loads at full capacity, and all transportation and services needed. So: loosing some generating power "gracefully" could be managed - if the loss is not sudden and unexpected, but as a result of different stations across region each going off line - and each being able to tell the central distribution stations that they are shutting down, and each distribution center being able to read, measure, control, and shuffle loads appropriately to keep the remaining stations safe.

This requires good data from the grid, control and sensing accurate from the grid, good comm's (everywhere) to allow changing and responding to shifts in demand, etc. requires that all the "lost stations" be dropped at different times (as if they had to shutdown for different reasons, or after different kinds of failure that affect each power plant differently at different times.

Under these conditions, the reserve capacity might be able to keep most areas of the grid up - if the whole grid remained connected. Selective outages - most likely, by cutting industrial power to the biggest loads, would mean that no business could be done on Monday/Tuesday/Wednesday...., but would possibly keep power to home users.

(You can cut entire huge individual loads to very large facilities centrally, but cannot cut off individual houses without cutting out the whole neighborhood at the substation. There is no practical way to cut off (or restore) individual houses one by one.)

---

Worse case?

Simultaneous loss of several power plants at the same time withno warning or central control. This surge/voltage spikes trips other plants before they can compensate, and even successfully remediated plants are tripped off. Regional blackouts ensue immediately as other sections of the grid lose control, sensors, and feedback, and as other automatic trips lock in based on conflicting and "inaccurate" data, actual "inaccurate" data, and actual "correct" data - some of which tells units to shutdown, some tell it that nothing has changed, and some tells it that things are operating successfully.

Some of the remaining plants are able to stay up, most trip off and have to be locally "black started" - but too few have emergency generators at the power stations to assume all the needed hotel loads (pumps, heaters, burners, coolers, recirc systems, etc.) to actually start off with the grid itself intact.

Recovery takes days (weeks to finish everything?), as the operating plants try to restart themselves using irregular procedures and unfamilar emergency operatin gmodes to get power down to the grid, then try to resume control of the grid distrbution, then restart the failed plants, then resume distribution to the failed sections (assumed now repaired) in the distribution system.

Then power gets to the first customers.

Not enough conventional plants have

-- Robert A. Cook, PE (Marietta, GA) (cook.r@csaatl.com), November 10, 1999.

The benchmark the government is using is that at rollover, when the embeddeds "bloom", the system is at 52% of capacity. As businesses come back to work after the weekend, obviously we would be at much more than 52%. So I would GUESS, that 40% loss is doable, depending on location/dispersment within each of the regional grids.

But they better be back up come Monday morning!

-- Duke 1983 (Duke1983@AOL.com), November 10, 1999.