The performance of primary frequency control has a significant influence on the power system stability and power quality. There are plenty of heat stored in the heat supply network of combined heat and power(CHP)units

which can improve the unit load-following performance without affecting the heat demand in a short time period. The static and dynamic model of heat extraction adjustment together with heat-power coupling model are set up. A new load-change idea according to the way of “rapid heat extraction adjustment

accurate fuel supply following

and steady heat extraction recovery” is proposed. A new load-change control strategy combining heat extraction adjustment and traditional coordinated control is given. A 330 MW CHP unit is taken as an example to verify the idea

and the results show that the strategy proposed can shorten the dead time of load response

quicken the load-change rate

and improve the performance of automatic generation control(AGC)through rapid regulation and active restoration of heat extraction.