Ann de Rouffignac
OGJ Online
Unprecedented forced outages of power plants Thursday prompted the California Independent System Operator (ISO) to warn Californians rolling blackouts may be imminent this evening.
ISO said Thursday morning that if nothing changes, it will begin shedding load at 5 p.m. PST in blocks of 100 Mw for 1 hr at a time. The blocks will be rotated from area to area hourly until 8 p.m.
After another 2,000 Mw of power tripped off line Thursday morning, bringing to 13,000 Mw the amount out of service, the ISO called a Stage 3 emergency, signifying blackouts have become a possibility. To keep the entire system from collapsing during peak demand, the grid operator may have to request utilities cut off 1,500 Mw of power for as long as 3 hr. Roughly 1 Mw serves 1,000 people, ISO officials said. Up to 1.5 million people could be affected.
�We made it through the morning, barely, with less than 1.9% of operating reserve,� said Kellan Fluckiger, the ISO's CEO. �The evening adds an additional 3,000 Mw of load.�
Without relief, Fluckiger says, rolling blackouts will be instituted but will be mostly confined to northern California. Relief could come in the form of conservation or more imports from the Northwest.
The state is not importing its maximum amount of power yet, Fluckiger said. Power imports from the Southwest can�t help California because of constraints in the middle of the state on Path 15, the transmission lines carrying electricity between the southern and northern regions of the state.
Order expired
The Department of Energy�s emergency order requiring power generators and providers to sell surplus electricity to California expired Wednesday night, but was reinstituted Thursday at the ISO's request. With or without the order, the Northwest is not in a position to sell much power to California because drought conditions have shrunk hydroelectric power supplies.
�We don�t have any surplus power. We can�t sell them power. We can only exchange power if it is returned to us within 24 hr,� said Mike Hansen, spokesman for Bonneville Power Administration (BPA), a federal entity with 11,000 Mw of hydroelectric power in the Northwest.
BPA agreed to ship 1,000 Mw-hr between 5-8 p.m. Thursday. The ISO agreed to return the power this weekend on a two-for-one megawatt basis.
In 20 years, Fluckiger says, he has never observed so many plants out for unexpected repairs at the same time. The winter storm affecting plants� cooling system intakes on the coast only worsened the situation.
Wednesday night, a large gas-fired unit experienced violent load swings and then tripped off line because of fuel supply problems. Then another unit had excessive vibrations causing it to trip off line.
Still another plant developed sudden boiler and condenser tube leaks. On top of that, a piece of mechanical equipment on the direct current line connecting Oregon and southern California failed. The failure reduced capacity on the line 350 Mw.
The ISO has asked all interruptible load in northern California to be cut off but still has some available in the South. But ISO officials said that load can�t be shed yet because it's needed to maintain voltage support on Path 15.