Posted on 08/16/2003 11:28:25 AM PDT by tictoc
Yep, the lights went out for 50 million people yesterday, and we still don't really know why it happened. Canada blames a fault in our system; we blame a fault in Canada's system, or a bad transmission line in the Midwest, but we're all sure it wasn't a terrorist.
Why? Just because nothing blew up?
Let's try a little experiment, change the word terror to sabotage. Sound any more likely now?
The leading theory on the root cause of the failure, at least, the leading theory as I rode in to work this morning, was the simultaneous failure of multiple transmission lines in the northern Mid-West US.
Hmmm. When I learned to trouble shoot, they taught us that multiple faults are very rare, and to look for a single fault first. If you seemed to be chasing a multiple fault, step back and look again. You probably missed something.
Here's a scenario to consider: Some idiot with an axe to grind and no sense of self preservation decides to die gloriously for Allah or whoever. He shorts two high tension transmission lines together, vaporizing himself while causing a cascading overload which shuts down power to 50 million people.
That's "simultaneous failure of multiple transmission lines."
This is offered as a possibility. I have no evidence, not even a hunch. Possibly a short occurred naturally, I don't know. But I'm getting a bit tired of the first words coming out of every politico's mouth when something happens being "It wasn't terrorism" when in truth, there's no way to know.
Don't lie to me.
OK, rant over. Now to the informative portion of this post.
There are a lot of folks griping about the collapse of the power grid, and the predictable voices are blaming the President, as if he had something to do with the design and construction of the grid. First of all, the thing wasn't designed; it grew. Second, it's not a monolithic system with some control room out of Star Trek. It's grunches of smaller, local systems interconnected, co-operative but independent of each other. Third, the complaint that "Somebody ought to do something" is easy; determining what to actually do is the hard part.
To give you some idea of how hard that question is, I have to take you into the complexities of the power grid, give you a tour of how it operates, and why it is set up the way it is. My knowledge in this area is based on my Navy career as Nuclear Reactor Operator. I didn't deal directly with the power distribution system, but through extensive cross training, I am familiar with the principles and techniques involved. And if I make any mistakes, I'm sure Sparky will correct me.
A simple power grid has three components:
The generator converts physical energy, ie movement, into electrical energy. The transmission lines carry this energy from the plant to the distribution center, where it is routed to the loads. If any of the three components fail, the grid goes down and the lights go out, and Auntie Eunice can't watch her stories.
Deciding that this was a bad thing, some fairly smart people decided that if you put two small generators instead of one big generator in the grid, if one failed, you could still handle most of the load with the one that was left, and Auntie wouldn't miss finding out if Jim and Suzy got married, even though Suzy was pregnant with Ralph's baby.
So that's what they did.
Now it gets interesting.
Two generators carrying the same load are said to be operating in parallel, like two horses pulling the same wagon. Now there has to be some way of controlling how much of the electrical load each generator is carrying, so that the system will be stable. Like our horse and wagon, if one horse is pulling harder than the other, not only is the off horse not doing his share of the work, but the wagon is also harder to steer. Unbalanced loads on parallel generators have a similar effect. Fortunately, it turns out that electricity is pretty cool, because it will automatically distribute the load based on the voltages the generators are putting out. The higher the voltage, the more load the generator will carry, reducing the load on the other generator. So we can control the output voltage of each generator to match the loads. Remember this bit, because it becomes very important later in the discussion.
So what we've done is increase the reliability of the system by building in backup generating plants, which adds both spare capacity, and redundancy. The problem is that building plants is expensive. There's a constant battle being fought over how much spare capacity the system needs, and how much redundancy is cost effective. Spare capacity costs money, but doesn't generate revenue, so plant owners want the minimum amount necessary to ensure reliability. Plant managers on the other hand, like to maximize spare capacity to be prepared for outages or overloads.
That's what a local system looks like. Now let's zoom out a little and look at the regional picture. We've got several local power grids, all working to supply power to their communities, all wrestling with the need to grow to meet demand, and to maintain enough spare capacity to handle outages. At some point, a couple of these systems got together, and realized that if they connected their power systems, they would increase their available spare capacity, and redundancy without having to build new plants. It was highly unlikely that a problem would strike both systems simultaneously, which meant that each system could rely on their own spare capacity, and the spare capacity of the other system to handle any outages.
The plant owners were happy with this arrangement, because now they could sell their spare capacity to another system, turning an overhead item into a revenue generating item. The plant managers were happy, because now they had enhanced redundancy, and massive spare capacity.
This is how the power grid came to exist. Discrete power systems interconnected to share both the load, and spare capacity.
"Now this all sounds great, but if the system is so stable, how come we still get massive blackouts?"
Well, there are two factors operating here. Many major cities do not generate anywhere near enough power to supply their loads. They depend on shared power from outside the city to meet their needs. The recent energy crisis in California was a perfect illustration of this. Due to outages, maintenance and other factors, the state could not generate enough electricity to meet its needs, and had to buy energy from other states. If a large city loses its access to that shared power, through a fault in the transmission or distribution system, it will not have enough power to sustain its load, and there will be a blackout. The second factor is that demand for electricity is outstripping supply. The grid has a fair amount of spare capacity under normal use conditions, but when power demand hits a peak, like it did this week due to the hot weather, spare capacity in the region is almost nil. Any outage at that point is extremely likely to cascade, spreading far beyond the initial blackout.
"That's the second time you've talked about a cascade. What do you mean?"
(Excerpt) Read more at shotsacrossthebow.com ...
Another blogger analyzed usage graphs from the Web and drew his preliminary conclusions here.
Terrorism, or sabotage, come in many forms. Not saying this is muslim connected or not. Just think "WORM" "WINDOWS". There's plenty of nasty-ass people out there to consider....JMHO.
FMCDH
If this is indeed the operative scenario, perhaps what's needed is to construct some thermal reservoirs near the plants which contain a fair amount of water along with some large resistive heating elements. In case part of the plant's load needs to be disconnected, divert energy into the reservoir. Since the water wouldn't generally be circulating, there wouldn't be any need for expensive purified water; rainwater would probably suffice for baseline usage, and tap water for replenishment.
That's outrageous. We can't go around letting people informing themselves and reaching conclusions while bypassing the New York Times.
Just goes to show, things we take for granted, like electricity, are not simple at all.
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