http://www.latimes.com/business/reports/power/lat_roll010509.htm

A Delicately Guided Dance With Darkness

Electricity: Reluctantly, engineers set off rolling blackouts to keep the entire grid from failing.

By NANCY RIVERA BROOKS, Times Staff Writer

The heart of darkness for Southern California is in Santa Ana. That's where engineers in Southern California Edison's Distribution Operations Center execute orders for rolling blackouts across the utility's 50,000-square-mile territory when the word comes down from Folsom, home of California's electricity grid operator.

It is a delicate balancing act, coordinated with other Edison operations centers in Fontana, Ventura and Dominguez Hills, to pull the plug on thousands of electricity customers when power supplies dip perilously low. At the same time, Edison must keep the juice flowing to users considered essential--hospitals, fire stations, police stations, air traffic controllers and prisons, among them.

The dance is replicated at Pacific Gas & Electric and San Diego Gas & Electric when commanded by the California Independent System Operator, which balances supply and demand on the grid for about 75% of the state.

"This is no fun," Edison spokesman Steve Conroy said. "We are in the business of keeping the lights on, not taking them down." California goes dark by stages according to an emergency plan maintained by Cal-ISO, the state's top electron traffic cop:

* Stage 1 means operating reserves have dropped below 7%. "Operating reserves" means generation that is not yet being used but could be, a kind of standby power. The utilities issue appeals for conservation.

* Stage 2 means electricity reserves are less than 5%; conservation pleas grow louder; large customers that get discount rates are asked to cut usage.

* Stage 3 means the state is within 1.5% of running out of available power; rotating power outages become likely to keep the electricity system from failing. The industry calls these blackouts "firm load interruptions." Cal-ISO coined a new term this week: "involuntary conservation."

Unlike an earthquake, which spreads out from an epicenter to wreak its damage, blackouts are scattered in clusters of circuits across each utility's service area. Edison bundles customers into groups of about 100 megawatts, with 1 megawatt providing enough power for 500 to 1,000 homes. Each of the roughly 110 groups contains business and residential, wealthy and poor, city and rural customers.

The power is cut automatically to most customers, but some crews must be sent out to open circuits manually to turn off the electricity. PG&E and SDG&E work similar blackout plans, grouping at least 40% of their total customers into such outage blocks. In a 500-megawatt outage, Edison would cut power to five groups for an hour. Electricity would then be restored to those customers, and another five groups would be blacked out if Cal-ISO said the need remained.

Edison limits customer outages to about an hour before moving on. PG&E and SDG&E's blackouts last 60 to 90 minutes. Once a group has been blacked out, it moves to the bottom of the list. PG&E customers have a jump on those of Edison and SDG&E. They are told in their monthl bills which outage block they are in and they can visit the PG&E Web site to see which is next for blackouts.

Edison and SDG&E were ordered last month by the California Public Utilities Commission to provide the same service. Without blackouts, the state's entire system would be at risk, repeating the 1996 outages that swept across Western states. "When we can control the situation and control where the outages are, you avoid a catastrophic collapse," Conroy said. "In an uncontrolled outage situation, blackouts last well beyond an hour and all customers are subject to them."

Copyright 2001 Los Angeles Times

-- Swissrose (cellier3@mindspring.com), May 09, 2001