Huge CA Outage Took 11 Minutes

Monday, September 26, 2011 @ 01:09 PM gHale


There was not enough coordination between the five power system operators during the Sept. 8 outage that left several million people in Orange and San Diego and Imperial Counties as well as part of Mexico and Arizona without power.

“There were 23 major events that occurred within an 11-minute time period within five different power grids,” said California Independent System Operator (ISO) spokeswoman Stephanie McCorkle.

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The outage began Sept. 8 at 3:27 p.m. when a worker in Arizona accidentally shorted the Southwest Powerlink, which feeds power to Imperial and San Diego counties.

To compensate for the loss, Imperial County started pulling power from the north, which shut down a line when it overloaded. Then, automated systems began pulling power from the San Diego area. At the same time, a power plant in Mexicali shut down and forced Baja, Mexico to pull power from the San Diego area as well.

Since San Diego was losing power to the east, it started pulling power from Orange County lines. When those lines overloaded, they shut down too.

“The powerlink from the north, coming through San Onofre and the local generation by itself is enough to supply San Diego but it’s not near enough to supply San Diego and Imperial County,” said San Diego State University professor Murray Jennex.

There should have been a barrier in place to prevent Imperial County from tapping into San Diego’s power, Jennex said.

There was no barrier or if there was, it was not working, so the entire area went black. The entire sequence of events took less than 11 minutes.

“What is not known at this point is why it occurred,” said McCorkle.

McCorkle said there are five different power operators that felt the impact of the power outage. She admitted the cooperation and communication between the five needs improvement.

It could take months before it has any results from its investigation, ISO officials said.



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