If a Balancing Authority loses a 700 MW reactor and frequency drops to 59.96 Hz, what happens to its ACE?

The correct understanding revolves around the concept of Area Control Error (ACE) within the context of Balancing Authority operations. When a Balancing Authority loses a 700 MW reactor, this impacts the generation and load balance within that area, causing a drop in frequency to 59.96 Hz, which indicates an imbalance.

The ACE is defined as the difference between the scheduled Net Interchange (NI) and the actual Net Interchange, along with a frequency component that accounts for the frequency deviation from the nominal target (usually 60 Hz). In this situation, the loss of the reactor effectively results in a decrease in available generation resources, leading to an imbalance and a deviation from the target frequency.

When frequency drops, it implies that there is not enough generation to meet the load currently being served. Consequently, the change in frequency will cause an increase in the ACE since the actual net interchange is less than the scheduled net interchange due to this deficit in generation. The system is unable to provide the expected power, thereby reflecting a net interchange decrease which contributes to a lower ACE. This results in the ACE decreasing by an equivalent of the MW lost, which corresponds to the 700 MW loss.

Understanding the dynamics of how generation resources impact frequency and, subsequently, how