Outage at Exelon’s Mystic plant drove tight ISO-NE Labor Day conditions
The outage at the Mystic plant, located in Boston, highlights the issues at stake in contentious debates over fuel security in New England and grid resilience at FERC.
On Sept. 3, ISO-NE implemented emergency operating procedures, purchasing power from neighboring regions and calling for voluntary conservation as real-time prices topped $2600/MWh.
ISO-NE said at the time that errors in its load forecast and unplanned outages caused the situation, but did not name a specific cause. Dolan said that conversations with companies in the market revealed Mystic was involved.
“Through conversations with market participants it was clear that Mystic was knocked off the system by an outside transmission outage,” Dolan said. “That certainly contributed to the issues, in addition to missing the load forecast.”
After Utility Dive reported the outage, Exelon said a power line fault affecting the neighboring Distrigas LNG import facility was to blame.
“The Distrigas LNG terminal experienced a power supply interruption around 3:30 p.m. on Sept. 3rd that resulted in a rare and significant fuel pressure reduction to Mystic Generating Station,” Exelon said in an emailed statement. “The loss of fuel pressure resulted in an automatic loss of power at Mystic [unit] 8 and partial loss of power at Mystic [unit] 9.”
ISO-NE does not release outage information for individual plants and declined to comment on whether Mystic was involved.
“We don’t identify resources that undergo forced outages, nor any financial charges or credits for any specific resource,” spokesperson Marcia Blomberg said via email. “That’s market-sensitive, confidential information.”
Blomberg said there were no forced outages on the ISO-NE transmission system that day, but that distribution lines not overseen by the grid operator could have caused other issues.