ABSTRACT
Automatic Generation Control (AGC) supplements the local control that occurs at power plants. Traditionally, AGC has been implemented as a simple feedback control system in which the error to be driven to zero is defined as having two components. The first component recognizes differences that may exist between actual and scheduled tie flows, and the second component accounts for deviations from scheduled frequency. AGC is currently accomplished in the United States in 136 control areas. It should be noted that control areas have responsibility not only for AGC, but also for scheduling power transactions. A more complete description of the role of AGC as it relates to economic operations may be found in most of the power system analysis textbooks published during the last 2 decades. Carefully tuning the AGC system is well justified by the very large economic savings that can be realized through interconnected operations, as compared to control areas operating as isolated entities.
