Home Power Grid

How it works

The power grid is the network of power supply lines interconnecting the power generation plants, switching systems, and the local power supplier.

Once upon a time, a power generating company would wire the area around its dam or whatever and switch this power to its customers.  This is still true but any one plant can no longer reliably deal with those customers.  Nor would you want it to.  If the dam had a problem, its customers would not have power until the dam was fixed.  The neighbors using the next dam would still have power.  So they have a switching station capable of handling both sets of customers from either dam.  Then the power companies involved have contracts on cross supply of power. 

Now imagine that this is true of all power companies across the country.

Well, not quite, this is a big country so there are three or four major grids.  You cannot imagine the complexity of the switching networks here.  At each switch point, there are circuit breakers in case something goes wrong.  Again the water pipe analogy is good here.  Think of each dam or windmill farm as a pipe supplying water (electricity) down line. The water pipes are all connected to each other in junctions and there are many smaller pipes going to communities then to individual homes.  When multiple sources are pumping water into the system, everything works as long as there is no pressure buildup in any of the junctions such that water would be forced back to one of the dams.

Oh. And in the northeast the power grid loops into Canada from Michigan to New York.

When Things Go Wrong

If things are working properly and one dam in the network finds backpressure from the network, that dams junction would be closed and the dam shut down.  When there was a higher demand and the pressure was removed from that junction, that dam could again produce water (electricity) and push it into the system.  Think of it as a 10-pound push from the dam and suddenly there is a 100-pound push from the network.  You shut down the dam or the water (electricity) goes the wrong way.

Any sudden surge, positive or negative, on the system activates shutdown procedures.  A broken line needs to be shutdown or people will get electrocuted.  There are computer consoles with multi-colored displays at each power junction indicating what is happening on all of the lines in and out.  Let’s say that a line goes down that is feeding the network.  This produces a sudden negative surge on the network.  If the network is fully loaded, and communicating with the grid about the line down, the grid will cover the load minimally until it can integrate another power source.

This same break causes a sudden positive surge on the local dam and the dam generators are cut down or totally shit off.  In this case, the network recovers and the local power company has an outage proportionate to the down side of the broken line.  If there is an alternate path to the down line customers and the downed line is isolated, the alternate source is activated and only those very local to the break are out of power until the line is repaired.

OK.  Now everything working, people are scrambling, the big yellow trucks are running.  The outage is fixed in minutes or hours or days depending upon the nature of the break.

The decision-making process (computers) takes milliseconds at each switch point.  The great New York shutdown of 2003 took a total of nine seconds.  This is critical.  Something did not communicate properly to cause the shutdown but the shutdown itself worked exactly right.  You did not hear this part.  Again think of a series of water pipes.  The water is flowing and something breaks.  We suddenly have a massive flood (short-circuit).  The whole system will dump its electricity into the break.  This will blow the pipes (melt the wires) in every switching station in the grid.  Each switch must open and absorb its local load or it will melt.  Remember, the water must go somewhere – you do not want the flood to occur in someone’s home.

A Story

I have always had eyes with very fast resolution.  I also had, until I got older, very acute vision.  I could read things most people only saw as blurs.  So I am working in a computer laboratory that is lit with fluorescent lights.  Fluorescent lights blink 60 times per second.  Most people’s eyes cannot see past 24 blinks per second.  Every afternoon the lab went black.  Then came back.  This was very disturbing to me.  More disturbing was the ridicule of my workmates who did not like me much anyway but though it absurd that the lab had gone black.  Their persistence of vision carried them through the blackout.  I called a friend of mine at the local power company (Mike Short, are you still at APS?)  I asked him what happened every afternoon about 2pm that would cause this.  He told me that the 4-corners power plant was integrated at that time to cover the additional load of the AC units in Phoenix.   The process took 2 or 3 power cycles before the Sine wave was properly synchronized.  He thought nobody could see 1/30 of a second.  These are the speeds that we are talking about and this was 20 years ago.

Another Story

About the same time as the blink thing, I was driving across the north side of Phoenix on Bell Road.  At this time Bell road was about as far north as Phoenix went.  I was driving toward Scottsdale from I-17.  Phoenix slopes down to the south so that from where I was driving, except for some mountains, I could see the entire city laid out to my right.

The city turned off.  It turned off in sections, basically west to east.  In a matter of seconds everything was black.  This included the signal and street lights around me.  I was glad I had the KZ-1000.  I was able to get around the drivers who suddenly had ego problems and were driving like madmen.  Realizing that this was a major event, I went to work and powered-down our network.  Then I went home to make sure the house would recover.

The problem?  There is a giant power line that runs from Oregon to Los Angeles.   This line went down.  Interestingly enough, this is a DC power line.  In any case, the break caused the network to hiccup all the way to Phoenix.  Some places in Arizona were without power for 20 minutes.  Some places for hours.  All in all, it was a power loss.  The New York thing seems about the same to me.  I guess New York thinks it is better than Los Angeles or maybe because we are more dependant than we were 20 years ago or maybe …

Synopsis

What happened in New York?  The network communication technology is obsolete.  In other words, we need more computer logic and more sensing equipment to make sure that when there is a break or surge that the network is informed and it takes appropriate buffering actions to contain and handle it.  Anything in this area requires decision-making speeds in seconds.  In a minute, the water will exit somewhere and it is best if that somewhere is controlled.

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Written:  2003          Updated:  Updated:  April 19, 2005          Back To Top