To accomplish the dispatching automation of the Hunan Power Pool (HPP), a supervisory control and data acquisition and automatic generation control/economic dispatch (SCADA+AGC/ED) system supplied by Systems Control in the USA was imported by the Hunan Power Dispatch Control Center. In December 1990 the practical implementation acceptance test for the new system was completed. The new system is the first system completed to use closed loop control of AGC in the power pools of China. This paper reviews the background of developing the new system, and describes implementation schemes and operation tests of AGC. At the same time, the Constant Net Interchange (CNI) mode of AGC in the HPP is also discussed in detail, and finally the economic benefits and the improved operation quality after AGC is in operation are described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>