Low electricity demand, brought on by unusually mild weather over the weekend, prompted PJM to issue a Minimum Generation Advisory.
On Friday, Jan. 10, electricity use dropped to 77,906 MW between 11 p.m. and midnight (for perspective, the all-time winter peak was more than 143,000 MW in 2015).
On Saturday, Jan. 11, with temperatures in PJM’s 13-state footprint in the 60s and 70s, the low, or valley period, was 69,289 MW between 3–4 a.m. On Sunday, Jan. 12, the valley was 64,458 MW between 3–4 a.m.
The Minimum Generation Advisory was issued to provide generators an advance warning that PJM could issue additional Minimum Generation Alerts or other Minimum Generation actions over the weekend. According to PJM’s operating procedures, PJM issues the advisory whenever electricity use is expected to be at or below 70,000 MW in the summer or winter, or below 65,000 MW in the spring or fall.
PJM did not issue any additional Minimum Generation Alerts or actions over the weekend, but did issue a High System Voltage action for the overnight hours on Jan. 12; voltages on the system tend to rise as the electricity use, or load, on the system decreases.
Keeping Power in Balance at All Times
Electricity must be produced and consumed on demand the instant it is needed.
At all times, the electricity generated and sent out onto the bulk electric power grid must match customers’ demand for it. This requires a constant balancing act achieved by PJM dispatchers working hand-in-hand with generators and other energy suppliers.
While we often think about how PJM calls for generation to come online as electricity use increases, a Minimum Generation Advisory shows how PJM can also call for generation to stand down when electricity use drops in order to maintain the reliability and stability of the transmission system. Read more about how PJM balances the supply and demand of electricity on the PJM Learning Center.