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TLDR; Caused by trees. And poor planning. FirstEnergy didn't adequately trim trees in the right of way for a 345 kV line. On a hot day, due to other outages,

by ghouse 8y ago

TLDR; Caused by trees. And poor planning. FirstEnergy didn't adequately trim trees in the right of way for a 345 kV line. On a hot day, due to other outages, the load on that line caused the conductor to heat, expand, sag, and then electricity shorted to the tree. Protection equipment removed the line from service, but with the loss of that transmission capacity, other lines also exceeded their capacity with their protection equipment tripping them offline. Planning criteria should have 1) prevented the first line from having as much load as it did, and 2) prevented the loss of the first line from causing cascading failures. Page 18 is a good place to start if you don't have the patience for the full 238 page report.

catawbasam 8y ago
FirstEnergy -- the same company currently gunning for a multi-billion bailout in the name of system reliability. :)
citrablue 8y ago
Failure to trim wild growth is a very common cause of massive wildfires.[0] In California, there's an incentive problem because the utilities try to charge the costs to the consumers. They have reduced economic incentive to maintain safe zones around their equipment. [0] http://www.latimes.com/business/la-fi-utility-wildfires-20171017-story.html http://www.latimes.com/business/la-fi-utility-wildfires-2017...
jcranmer 8y ago
That's not a fully accurate situation. The most damning thing is that FirstEnergy didn't realize their system was falling apart. They lost alarm notifications at 2:14, and didn't realize that things were bad for another hour and a half. The first transmission line to fail completely [1] wasn't discovered by anyone until after the blackout, and FirstEnergy was called about the first transmission line failure but they dismissed it as a fluke because they received no notification of its failure. It took several people calling them asking about line failures before they realized that they weren't seeing their internal notifications, and by that time, their system was pretty much one minor thing away from disaster. The only actual recourse they would have had at that point would have been to start disconnecting people from their system. That takes time, and by the time they realized that they were in such an emergency, it was too late. The system was already collapsing and the full blackout was just 20 minutes away. [1] The Star-South Canton transmission line crossed company boundaries and failed twice then immediately automatically reconnected before failing for good a third time. The first failure precedes the Harding-Chamberlain failure, while the other two failures occurred after two lines were off for good, so this line's failure is considered the third failure.
gizmo686 8y ago
I'm still working through the report, but your TLDR seems wrong. The report seems to be repeatedly emphasizing that the grid is supposed to be resilient to unpredictable failures at unpredictable times. While the trees were the immediate cause [0], the real story of the outage was the resulting cascade failure, which absolutly should not have happened. To take a CS example, when Google/Amazon/etc suffer a cascade failure, they do not blame the proximal cause (such as a few nodes getting overloaded), but rather their load balances and failure recovery systems for allowing/causing the problem to cascade into a full network failure. [0] And a result of inproper vegetation management

by ghouse 8y ago

catawbasam 8y ago

FirstEnergy -- the same company currently gunning for a multi-billion bailout in the name of system reliability. :)

citrablue 8y ago

Failure to trim wild growth is a very common cause of massive wildfires.[0] In California, there's an incentive problem because the utilities try to charge the costs to the consumers. They have reduced economic incentive to maintain safe zones around their equipment. [0] http://www.latimes.com/business/la-fi-utility-wildfires-20171017-story.html http://www.latimes.com/business/la-fi-utility-wildfires-2017...

jcranmer 8y ago

That's not a fully accurate situation. The most damning thing is that FirstEnergy didn't realize their system was falling apart. They lost alarm notifications at 2:14, and didn't realize that things were bad for another hour and a half. The first transmission line to fail completely [1] wasn't discovered by anyone until after the blackout, and FirstEnergy was called about the first transmission line failure but they dismissed it as a fluke because they received no notification of its failure. It took several people calling them asking about line failures before they realized that they weren't seeing their internal notifications, and by that time, their system was pretty much one minor thing away from disaster. The only actual recourse they would have had at that point would have been to start disconnecting people from their system. That takes time, and by the time they realized that they were in such an emergency, it was too late. The system was already collapsing and the full blackout was just 20 minutes away. [1] The Star-South Canton transmission line crossed company boundaries and failed twice then immediately automatically reconnected before failing for good a third time. The first failure precedes the Harding-Chamberlain failure, while the other two failures occurred after two lines were off for good, so this line's failure is considered the third failure.

gizmo686 8y ago

I'm still working through the report, but your TLDR seems wrong. The report seems to be repeatedly emphasizing that the grid is supposed to be resilient to unpredictable failures at unpredictable times. While the trees were the immediate cause [0], the real story of the outage was the resulting cascade failure, which absolutly should not have happened. To take a CS example, when Google/Amazon/etc suffer a cascade failure, they do not blame the proximal cause (such as a few nodes getting overloaded), but rather their load balances and failure recovery systems for allowing/causing the problem to cascade into a full network failure. [0] And a result of inproper vegetation management