What is the normal frequency control mode used by PJM?

The normal frequency control mode used by PJM is tie-line bias. This approach systematically manages frequency by adjusting generation based on the net change in frequency resulting from power flow across interconnections or tie-lines with neighboring systems.

The tie-line bias method allows PJM to stabilize the frequency by ensuring that the amount of power flowing across these interconnections reflects the operational needs and conditions of the interconnected grid. When there is an increase in frequency, PJM may reduce generation or increase load to restore balance, while a decrease in frequency would prompt an increase in generation or decrease in load.

This mechanism is crucial in maintaining system reliability and stability, as frequency deviations can lead to imbalances that threaten the integrity of the power system. In this context, tie-line bias effectively aligns generation output with the demands expressed by both the local load and interconnected systems, thus being the primary mode of frequency control for PJM.