SPP set a new peak load record last week as a heat dome left much of the Midwest sweltering in near 100-degree Fahrenheit temperatures.

Regionwide electricity usage in SPP’s 14-state footprint reached 51.04 GW at 4:24 p.m. CT on Wednesday. The RTO’s previous record came in August 2019, when peak load bit 50.67 GW.

The grid operator declared conservative operations, beginning at noon Thursday and ending at 8 p.m. Friday. However, it extended a resource alert until 8 p.m. Saturday. It was originally to have ended Friday night.

When operating under conservative operations, SPP can commit generation to serve load earlier than during normal operations and ahead of standard day-ahead market processes. The declaration alerts market participants that they should make available all necessary generating resources to meet the expected high demand.

The RTO had issued the resource alert for July 26 to 30. It uses resource alerts when severe weather conditions, significant outages, wind forecast uncertainty and/or load forecast uncertainty are expected.

ERCOT has been running under conservative operations since June, increasing its supply of operating reserves and using reliability unit commitments to strengthen grid reliability. (See ERCOT Stakeholders Sign Off on More Ancillary Services.)

Those measures have helped the Texas grid operator meet demand without falling back on emergency actions. ERCOT warned last week that it might reach its record peak this week of 74.8 GW, set in 2019. Staff forecasted a load of nearly 74.7 GW on July 26, but it came in at 72.9 GW, its high for the week.

The load forecasts for Sunday and Monday were nearly 74.8 GW and 76.9 GW, respectively. High temperatures are expected to be at or above 100 F through Aug. 6.

MISO last week instituted a hot-weather alert meant to prepare operations personnel and facilities for potential conservative operations. The alert expired Wednesday evening.