The California Independent System Operator (ISO) declared a Stage 2 emergency Thursday after a fire at the Oregon border unexpectedly cut power deliveries into California. The ISO earlier issued a Stage 1 warning and requested supplemental energy bids of up to 3,000 Mw.
Power plants totaling 3,964 Mw of electricity are also off line Thursday due to mechanical failure or planned maintenance that could not be postponed, the ISO said. It said the fire was reportedly caused when a transmission line that is part of the crucial California-Oregon Intertie sagged into a tree, igniting the fire. Power deliveries into California on the path of the lines have been cut by several hundred Mw, the ISO said.
It said fires affecting power supplies in southern California Wednesday have been contained and are not a factor in today's resource shortfall.
The ISO said electricity consumption is expected to peak about 4 p.m. PST, drawing more than 40,482 Mw from the ISO-controlled power grid. At 1:30 p.m., loads already totaled 39,197 Mw.
The ISO said the alert is in effect through 7 p.m.
The grid manager said it will attempt to maintain stability of the transmission system without activating voluntary load management programs. If conservation measures are insufficient in lowering the demand for power, the ISO said load management programs that implement voluntary curtailments of power are probable.
On Wednesday, the ISO called a Stage 2 alert after reserves dropped below 5%. At this level, large commercial customers that have signed up to voluntarily curtail power during high demand days are asked to begin shedding load.