Wind farms must be able to output active power according to grid dispatch instructions when connected to the grid. Due to the significant reduction in power electronic devices and the adoption of constant voltage-to-frequency ratio control operation principle, dynamic low-frequency wind power systems are more economical and reliable in the development prospects of deep-sea areas. To solve the problem that this system can only track the maximum power and cannot output active power according to grid dispatch instructions, a centralized variable-frequency wind farm active power control method considering active speed-up of the turbine cluster is proposed. By coordinating variable-frequency control and variable-pitch control, the problems encountered during control mode switching is solved. Comprehensively considering the operating and control characteristics of dynamic low-frequency wind power systems utilizing centralized transmission frequency, a suitable active power allocation method for wind farms is designed, which balances turbine rotatioanl speed and reduces pitch angle adjustments. Finally, the correctness and effectiveness of the proposed method are verified through PSCAD simulation models. The calculation results show that the proposed active power control method can effectively track grid dispatch instructions for active output of dynamic low-frequency wind farms, while also storing more kinetic energy, which helps to improve the control level of wind farms.