Mike Noth on behalf of the Performance, Disturbance, Compliance Working Group (PDCWG)
This System Change Request (SCR) updates the formula used by the Resource Limit Calculator to calculate the Generation To Be Dispatched (GTBD) value. The update will include the addition of Area Control Error (ACE) Integral times a configurable factor that captures the long-term Dispatch trend to help minimize GTBD oscillations from one Security-Constrained Economic Dispatch (SCED) interval to the next. The analysis further shows that having an Integral ACE feedback would reduce the amount of manual Time Error corrections performed.
Integral ACE is calculated from Raw ACE by integrating the raw ACE value over a configurable amount of time (X seconds) and adding it to the previous 4 second Integral ACE, as shown below:
Integral ACE (current 4 sec) = Integral ACE(last 4 sec) + [(Raw ACE(Current 4 sec)*(Current Time – Last AGC run time))/X]
In general, Integral ACE provides a good indication of which direction ACE has been trending.