The California Independent System Operator (CAISO) declared a Stage 3 Electrical Emergency Saturday evening due to increased electricity demand, the unexpected loss of a 470-megawatt (MW) power plant, and loss of nearly 1,000 megawatts of wind power.
The emergency was declared at 6:28 p.m. The load was ordered back online 20 minutes later at 6:48 p.m., as wind resources increased.
Portions of Santa Cruz, Monterey and San Joaquin counties have been affected. By 8 p.m., the power was being restored in some affected regions, including in the city of Santa Cruz.
A Stage 3 Emergency is declared when demand begins to outpace available supply, and grid operators need to tap electricity reserves to balance the grid. Rotating power interruptions of about 470 megawatts were initiated across the state.
Extreme heat throughout the West has increased electricity usage, causing a strain on the power grid. All available resources are needed to meet the growing demand. The California ISO is working closely with California utilities and neighboring power systems to manage strain on the grid and to restore the power grid to full capacity.
As portions of the grid are restored, local utilities will restore power in a coordinated fashion. Although a Stage 3 Emergency is a significant inconvenience to those affected by rotating power interruptions, officials say it is preferable to manage an emergency with controlled measures rather than let it cause widespread and more prolonged disruption.