PG&E meteorologists explain how they know when a planned power shutoff is needed - KCRA Sacramento

PG&E explains how it knows when to do a planned power shutoff

PG&E meteorologists explain how they know when a planned power shutoff is needed

Meteorologists at PG&E are responsible for identifying days where weather may increase the risk for equipment damage and potential fire starts.

Some Northern California communities experienced their first Pubic Safety Power Shutoff (PSPS) of the season on Wednesday.

The PSPS is a system Pacific Gas & Electric Co. uses in determining when wildfire risk warrants planned shutoffs. PG&E makes the decision to use a PSPS on days when its Meteorology and Fire Science team identifies weather factors that increase the risk of damage to lines that could then ignite a vegetation fire.

"What we do is make sure that the utility puts the right people in the right place to respond the most efficiently," said Evan Duffey, who manages weather forecasting operations for PG&E.

Duffey and a team of six full-time meteorologists analyze the weather forecast for each sector of PG&E's grid systems.

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Each one of those sectors, or circuits, can experience very different weather, requiring a very precise approach to forecasting.

To meet that need, PG&E uses data science to analyze past incidents and compare them with expected conditions.

"What we're trying to do is understand exactly what combination of, maybe high winds with moderate humidity, or low humidity with high heat, could cause issues for each circuit," said Sean Gilleran, a principal data scientist for PG&E.

On days when risk factors are at their most extreme, PG&E utilizes PSPS.

A newer, more intermediate precaution is being used when fuels are very dry, but weather risk factors are low. PG&E calls it Enhanced Powerline Safety Settings.

EPSS can automatically trigger a localized outage when a surge is detected. A pilot program for the technology began in 2021. Last year, EPSS was expanded to cover all high-risk lines in California.

"These are settings that already exist that open up circuits when something falls on the lines," said Eric Lamoureux, deputy director of PG&E's EPSS program.

According to PG&E, EPSS reduces the time to de-energize a line from one second to one-tenth of a second, limiting the potential for a fire.

"We saw a 68 percent reduction in the number of ignitions that occurred throughout our service territory compared with the prior three-year average," Lamoureux said.

So far, in 2023, EPSS has triggered approximately 1,000 outages in PG&E's coverage area. Lamoureux said that PG&E believes that each one of those outages is a fire prevented, but acknowledges that this new system can be frustrating for customers.

"We don't want to turn this protection on unless we absolutely have to," Lamoureux said.

And just like with a PSPS, the decision to use EPSS in a community begins with forecasts made by the PG&E weather team.