Combined with characters of 2×300 MW units in Datang Baqiao Thermal Power Plant

and that of 2×300 MW units in Sagardighi power plant of India

the control mode of units under operating condition of run back(RB) has been analysed

and their control stratege being optimized and tested.Test shows that the adoptation of constant pressure mode for main steam pressure control is helpful to constrain the rapid decrease of steam temperature during the time of RB operation.Decreasing load under constant pressure

the original operating condition of unit can quickly be restored.For RB of the primary air fans

different control stratege should be adopted due to different characters of equipments used for units.