SOS: NERC Terms and Definitions

Area Control Error (ACE) CORRECT ANSWER-The instantaneous difference between a Balancing Authority's net actual and scheduled interchange, taking into account the effects of Frequency Bias, correction for meter error, and Automatic Time Error Correction (ATEC), if operating in the ATEC mode. ATEC is only applicable to Balancing Authorities in the Western Interconnection. Reporting ACE CORRECT ANSWER-The scan rate values of a Balancing Authority's ACE measured in MW, which includes the difference between the Balancing Authority's Net Interchange Actual and is Net Interchange Scheduled (NIs), plus its Frequency Bias obligation, plus any known meter error. In the Western Interconnection only, Reporting ACE includes Automatic Time Error Correction (ATEC). Regulation Reserve Sharing Group CORRECT ANSWER-A group whose members consist of two or more Balancing Authorities that collectively maintain, allocate, and supply the Regulating Reserve required for all member Balancing Authorities to use in meeting applicable regulating standards. Reserve Sharing Group Reporting ACE CORRECT ANSWER-At any given time of measurement for the applicable Regulation Reserve Sharing Group, the algebraic sum of the Reporting ACEs (or equivalent as calculated at such time of measurement) of the Balancing Authorities participating in the Regulation Reserve Sharing Group at the time of measurement. Control Performance Standard (CPS) CORRECT ANSWER-The reliability standard that sets the limits of a Balancing Authority's Area Control Error over a specified time period.