If frequency decreases due to external generation loss, what will remain constant?

When frequency decreases due to external generation loss, the concept of Area Control Error (ACE) remains constant. ACE is a critical parameter that reflects the balance between generation and load in a specific control area, incorporating both the frequency and scheduled interchange flows with neighboring areas.

In situations where generation is lost, the frequency drops because there is not enough generation to meet the load demand. However, while the frequency changes, the ACE calculation takes into consideration the scheduled generation and load, and it maintains the necessary adjustments to bring the system back to its targeted values. This means that while frequency may dip, ACE serves as a control tool indicating how much generation needs to be adjusted to restore balance.

In contrast, generation capacity is tied to what is available at any given moment, which changes with loss events. Energy consumption is influenced by the load demands, which can also shift in response to frequency changes. Automatic control actions may take place to correct deviations, but they are responses to changes rather than constants during a frequency drop. Thus, ACE is the parameter that properly maintains its relevance in the face of changing system conditions due to generation loss.