Being the only Power Engineer in my group of friends I will attempt to answer a decent number of questions raised:
Q: Why was the blackout so wide spread?
A: A number of factors could lead to this, most of it was the grid failed fairly quickly, the grid was stressed and the all plants were at peak capacity. When the automated protect circuitry kicked in to protect the system most of the trips would have been over voltage which are substantially faster trips than say over current. The overvoltage in fact would travel as a transient wave on the power lines at the speed of light all the way back to the power plants where the main generator protection would trip to keep from arcing the generator windings. Also power plants tend to be grouped in certain regions, many regions (think urban) don't generate enough to support themselves.
Q: Why are they saying some stations have damage?
A: Sometimes the generator protection isn't fast enough to prevent the transient from making it back to the source. Also if there isn't a place for the energy to go, the generator having a huge amount of inductance and generating in the kilo amp range, will create an open circuit voltage large enough to arc itself. Generator protection is a last resort; it is preferable to take out load in a controlled manner.
Q: Why will it take so long to repower everything?
A: Power in the United States is distributed using AC at 60Hz. Each and every generating station has to be synchronized with the grid at the connection point or else there will be a tremendous amount of harmonics generated and thus huge amounts of power wasted (plus a whole slew of power related problems that I won't get into). So when the whole grid goes down like it has the power companies and ISOs have to energize the main power transmission lines while leaving all consumers and generators off, then bring up generators near the border of the black-out first and gradually move toward the center of the blackout. This is because it takes time for a signal to propagate between point A and point B, thus while the whole grid is in sync at 60Hz there is a phase difference between point A and B associated with the distance between. Granted this could be accomplished with modern technology but power plants don't have any newer technology than what would have been state of the art in about 1970. Also the time it takes depends on the type of plant and type of trip. For Example take a steam (nearly all big ones) power plant: generator protection notices an over-voltage occur on the line, it trips and takes the generator out of the circuit, the generator over-voltages, so the winding energizer shuts down removing load from the steam turbine, the turbine overspeed protect trips and cuts steam pressure, the boiler preasure relief goes and now the plant is totally off-line. It takes about a week to bring a boiler online from cold. So lets hope the big plants didn't have trips going all the way back to the steam system.
Q: Why did some states loose power while their neighbors didn't?
A: Due to de-regulation the grid is segmented by ISOs and they have to buy power from one place and sell it to another until eventually the person buying it is a consumer. Some states at that time were not selling near their peak capacity either because they were charging more than someone else or because the interconnect was too week to supply that much. I would suspect a combination of the two.
Q: Why was the blackout so wide spread?
A: A number of factors could lead to this, most of it was the grid failed fairly quickly, the grid was stressed and the all plants were at peak capacity. When the automated protect circuitry kicked in to protect the system most of the trips would have been over voltage which are substantially faster trips than say over current. The overvoltage in fact would travel as a transient wave on the power lines at the speed of light all the way back to the power plants where the main generator protection would trip to keep from arcing the generator windings. Also power plants tend to be grouped in certain regions, many regions (think urban) don't generate enough to support themselves.
Q: Why are they saying some stations have damage?
A: Sometimes the generator protection isn't fast enough to prevent the transient from making it back to the source. Also if there isn't a place for the energy to go, the generator having a huge amount of inductance and generating in the kilo amp range, will create an open circuit voltage large enough to arc itself. Generator protection is a last resort; it is preferable to take out load in a controlled manner.
Q: Why will it take so long to repower everything?
A: Power in the United States is distributed using AC at 60Hz. Each and every generating station has to be synchronized with the grid at the connection point or else there will be a tremendous amount of harmonics generated and thus huge amounts of power wasted (plus a whole slew of power related problems that I won't get into). So when the whole grid goes down like it has the power companies and ISOs have to energize the main power transmission lines while leaving all consumers and generators off, then bring up generators near the border of the black-out first and gradually move toward the center of the blackout. This is because it takes time for a signal to propagate between point A and point B, thus while the whole grid is in sync at 60Hz there is a phase difference between point A and B associated with the distance between. Granted this could be accomplished with modern technology but power plants don't have any newer technology than what would have been state of the art in about 1970. Also the time it takes depends on the type of plant and type of trip. For Example take a steam (nearly all big ones) power plant: generator protection notices an over-voltage occur on the line, it trips and takes the generator out of the circuit, the generator over-voltages, so the winding energizer shuts down removing load from the steam turbine, the turbine overspeed protect trips and cuts steam pressure, the boiler preasure relief goes and now the plant is totally off-line. It takes about a week to bring a boiler online from cold. So lets hope the big plants didn't have trips going all the way back to the steam system.
Q: Why did some states loose power while their neighbors didn't?
A: Due to de-regulation the grid is segmented by ISOs and they have to buy power from one place and sell it to another until eventually the person buying it is a consumer. Some states at that time were not selling near their peak capacity either because they were charging more than someone else or because the interconnect was too week to supply that much. I would suspect a combination of the two.
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