What is the minimum percentage of time that the BA should maintain ACE at zero for reportable disturbances?

The requirement for Balancing Authorities (BAs) to maintain their Area Control Error (ACE) at zero is crucial for ensuring the reliability and stability of the power grid during reportable disturbances. The expectation is that for critical disturbances, the BA should be able to manage its ACE, effectively keeping it at zero 100% of the time. This standard is essential for accurate system balancing, as any deviation from zero ACE can indicate a mismatch in generation and load that might escalate into further reliability issues.

Maintaining a zero ACE ensures that the grid remains stable and reliable, as it signifies that the electricity supply meets the demand without any excess or deficit. This is particularly important in scenarios where disturbances such as generation outages, load fluctuations, or unforeseen events could impact grid reliability. The ability for a BA to respond promptly and maintain ACE at zero under these circumstances is a fundamental requirement within the NERC reliability guidelines.

Achieving this standard enables a stronger foundation for overall grid resilience and supports the integrity of the interconnection, as it minimizes the potential for cascading failures or other reliability challenges.