What is the value the ACE must return to in order to avoid a DCS violation?

To avoid a DCS (Disturbance Control Standard) violation, the ACE (Area Control Error) must return to a specific value, which is typically defined as the acceptable operational range determined by the specific reliability standards set by NERC (North American Electric Reliability Corporation). In this context, a return to -55 MW suggests that the area is operating within a range that effectively balances generation and load while taking into account the specific characteristics of the grid in question.

The value of -55 MW indicates that the system is slightly over-generating to meet the required generation levels after accounting for different factors such as frequency control and interchanges with neighboring areas. Aiming for this specific ACE value helps ensure that the area remains compliant with reliability standards, helping to maintain system stability and avoid any violations that could lead to further system issues or penalties.

In contrast, values like 0 MW, 700 MW, and 8500 MW suggest either a neutral condition, high levels of net load generation, or an excessively high generation level, all of which could lead to potential violations of operational standards in some scenarios. Therefore, returning to a specific ACE value of -55 MW is crucial for maintaining both reliability and system integrity.