In the active power control device of the wind farm connected to the grid operation centrally, the invention increases the droop frequency regulation control strategy of the wind farm power, and monitors the frequency of the wind farm connected to the grid centrally in real time, When the frequency of the merging point exceeds the set primary frequency modulation dead time, according to the drooping frequency regulation control strategy of the wind farm power, the primary frequency modulation power target value PPFR of the energy management platform after the primary frequency modulation operation is calculated, The primary frequency modulation measurement and control system reallocates the new primary frequency modulation power target value PPFR to each wind turbine through the energy management platform. The wind turbine adjusts its output according to the instruction, and realizes the primary frequency modulation function of the wind farm as a whole, so that the primary frequency modulation of the wind farm and the AGC control of the wind farm can be coordinated.