PJM reliably served demand through extreme hot weather May 18–20, which was made increasingly challenging during typical spring shoulder season maintenance outages, well-above-average temperatures across much of the PJM region, and transmission congestion in the Mid-Atlantic and Dominion zones, Paul Dajewski, PJM Sr. Manager – Dispatch, said at the June 4 Operating Committee meeting.
In coordination with generation and transmission owners, PJM kept the power flowing in its footprint and served an instantaneous peak load of 136,222 MW, logged May 19, the second-highest May peak in over a decade.
“For us to have a day where our load is 136,000 MW in mid-May is significant,” Dajewski said, noting the extreme heat took place near the end of the spring shoulder season, at a time when generation maintenance outages remained notable. “Had this happened more in the middle of the season, the consequences would have been more severe.”
Shorter Shoulder Seasons
Fall and spring, referred to as the shoulder seasons, are typically reserved for maintenance by generation and transmission owners to prepare facilities to perform during peak winter and summer periods.
As hot weather approached, PJM Operations worked to verify that facilities were coming back online on time from previously scheduled outages. In addition, generation and transmission owners responded by postponing new outage work.
On the heels of the previous heat event in mid-April, PJM Operations is contending with more extreme weather events during shoulder seasons, Dajewski said, while working to meet reserve requirements. “We do realize shoulder seasons are getting shorter and shorter,” he noted, adding PJM is working with precision when seeking delays or rescheduling of routine maintenance by generation and transmission owners. “We try to take that into consideration before we make those kinds of requests.”
In contrast, PJM is prepared to serve loads in excess of 150,000 MW this summer, when scheduled outages are rare and more equipment remains in service.
Emergency Procedures Activated
With a forecast of 90-degree-plus temperatures, PJM issued a number of emergency procedures to operate the system reliably during the heat stretch:
- Maintenance Outage Recall to return equipment to service by May 18
- Hot Weather Alert for the PJM region (excluding the ComEd zone) on May 18 and for the Mid-Atlantic and Southern areas for May 19 and 20. This alert is a routine procedure PJM issues ahead of forecasted hot weather and/or high humidity to prepare transmission and generation personnel and facilities for expected increases in demand.
- Maximum Generation Alert and Load Management Alert for May 18 and 19 for the entire PJM region and May 20 for the BGE, Pepco and Dominion service areas. This alert is targeted at transmission/generation owners, who then determine if any maintenance or testing on equipment can be deferred or canceled. By deferring maintenance, the units stay online and continue to produce energy that is needed to serve electricity demand within the PJM region.
- Low Voltage Alert and Heavy Load Voltage Schedule Warning for May 18–20. The purpose of both emergency procedures is to increase bulk electric system voltage to allow for additional transfer capability across critical transmission interfaces.
In addition, Pre-Emergency Demand Response helped ease constraints and contingencies for unscheduled transmission or generation outages in the BGE, PEPCO and Dominion service areas on May 18 and 19. PJM also called for Pre-Emergency Demand Response in the Columbus, Ohio, area on May 19. Demand response or load management customers are paid to reduce their electricity consumption to ease demand during critical periods.
Dajewski said that cooperation from transmission and generation owners was essential to bring equipment back or postpone new jobs during the heat event. “The coordination and willingness to postpone some of these projects had a significant impact on reliability,” he noted.
DOE 202c Order Granted
On May 17, before the onset of the severe heat, PJM also requested and was granted approval under an emergency 202c order by the U.S. Department of Energy to direct transmission owners, if required as a last resort prior to voltage reduction or load shed, to curtail data centers and other large loads that have backup generation.
PJM requested and was granted similar permission in January during Winter Storm Fern due to the extremely cold temperatures.
While PJM did not require data centers or other large load customers to curtail or move to backup generation during either weather event, the DOE Order offers one more tool to minimize the risk of outages to customers.