PJM has proposed new reliability standards that would require data centers and other large computing loads to stay connected to the grid during voltage and frequency disturbances, instead of disconnecting and switching to their own backup generation.
The proposal, announced Sept. 8, follows a July 22 event in which nearly 4,000 megawatts of data center load in northern Virginia unexpectedly disconnected from the PJM power grid and switched to backup generators. PJM and Dominion operators had to respond quickly to imbalances between load and generation, along with spikes in transmission voltage and frequency. The grid did not suffer reliability impacts that could not be resolved that day, but it was the third separate measurable event of this kind in the last two years, said David Souder, PJM's executive director of system operations. "This type of operation is unsustainable and needs to be addressed," Souder told the PJM Planning Committee.
What the proposal would require
Introduced at the Sept. 8 Planning Committee meeting, the proposal would set new standards requiring Large Load facilities, PJM's term for computational loads including data centers and crypto-mining operations, to stay connected through normally cleared transmission disturbances. That means "riding through" voltage and frequency excursions beyond normal operating limits without adding reliability risk for the grid. The standards would cover minimum voltage and frequency ride-through requirements for both existing and future Large Loads. Byoungkon Choi, PJM's principal engineer for generator modeling and dynamic studies, said PJM staff plans to work with existing facilities on a transition plan to adjust their operating parameters to comply. "PJM plans to establish these requirements as soon as possible," Choi said.
FERC order and timeline
The action also responds to a June 18 order from the Federal Energy Regulatory Commission requiring PJM to identify gaps in how it evaluates the reliability impacts of Large Loads. FERC's order states it is concerned that PJM's tariff does not specify ramp rate or ride-through requirements for the transmission customers serving large loads. PJM plans to file proposed solutions with FERC in November, and will hold a Planning Committee special session on large-load ride-through education on Sept. 15.
Other grid operators moving too
PJM's proposal follows standards already advanced by grid operators MISO and ERCOT, and by PJM transmission owners Dominion and American Electric Power. The North American Electric Reliability Corporation is also developing Large Load reliability guidance and ride-through recommendations and standards.
