How is the Frequency Response Obligation (FRO) determined for a Frequency Response Sharing Group?

The determination of the Frequency Response Obligation (FRO) for a Frequency Response Sharing Group is based on the sum of the individual FROs of each member. This approach ensures that the group collectively possesses enough frequency response capability to effectively support the grid during frequency disturbances.

By adding the individual FROs, the group establishes a total response capacity that reflects the combined ability of its members to respond to frequency deviations. This collective obligation is important for maintaining reliability within the power system, as it helps ensure adequate support in the event of a sudden loss of generation or other disturbances that might cause a frequency drop.

In contrast, averaging the individual FROs would not provide an accurate measure of the group’s ability to respond in a frequency event, as it could potentially underestimate the total capacity needed. Similarly, taking the maximum FRO of all members does not account for the capabilities of the entire group working together, which is necessary for ensuring responsiveness. Assessing the overall system load may provide contextual information but does not directly inform the collective FRO obligation of the sharing group.