PJM weighs stricter grid reliability rules for data centers after 4GW Virginia outage

PJM Interconnection, the largest regional transmission operator in North America, is considering changes to interconnection reliability requirements for data centers and cryptocurrency mining facilities following a major outage in Virginia late last month. The incident, which occurred on July 22 and originated in northern Virginia—home to the world's highest concentration of data centers—took nearly 4GW of data center capacity offline, marking the largest such event ever recorded across PJM's footprint.

According to Dominion Energy, the utility serving the region, a transmission line went out of service on the morning of July 22, prompting data centers in the area to disconnect from the grid and switch to backup power. While PJM reported that the grid did not experience significant reliability impacts during the event, it did see a high imbalance between generation and load, along with large swings in voltage and frequency—conditions that can stress physical grid infrastructure.

In the aftermath, PJM's operating committee convened a meeting with Dominion to review preliminary findings, system impacts, and ongoing efforts to develop standards for reliably integrating large-scale computational loads onto the bulk power system. The discussions are part of a broader push to address the unique challenges posed by data centers, which are highly sensitive to voltage fluctuations and often trip offline during grid disturbances.

"This was a normally cleared fault," said Emanuel Bernabeu, chair of PJM's operating committee. "They should not disconnect from the grid. These data centers are too sensitive to the kind of voltage that they like, and we feel they are disconnecting too early." Bernabeu added that PJM and Dominion are continuing to jointly review the event and system impacts, with an eye toward stakeholder coordination for new standards.

Matthew Wharton, PJM's manager of reliability engineering, said the RTO is "currently evaluating potential enhancements to reliability requirements, with consideration of existing and future industry ride-through standards and practices." The goal is to ensure that data centers remain connected during grid disturbances, reducing the risk of cascading reliability issues.

The incident highlights a growing concern for grid operators as data center demand continues to surge. Many facilities configure their protection systems to detect sudden voltage changes and rapidly switch to on-site backup generation, a response that can raise system frequency, create generation-load imbalances, and increase voltage levels—potentially damaging grid equipment. Without updated standards, such outages could become more frequent as computational loads expand.

Federal regulators have taken notice. In July, the Federal Energy Regulatory Commission ordered the North American Electric Reliability Corporation to define and create the first phase of enforceable reliability standards aimed at managing the risks posed by computational loads. PJM's proposed changes would complement those efforts, potentially setting a precedent for other RTOs grappling with similar challenges.