Abstract：In response to the potential frequency secondary drop problem of direct-drive wind power systems

in the scenario of continuous frequency drop faults in the power grid，the principle of primary frequency regulation

of direct-drive wind power systems was analyzed. A primary frequency regulation control strategy for direct-drive

wind power systems was proposed based on the product and difference combination of frequency change rates at

pre- and post-sampling times. According to the established criteria，the droop coefficient of the direct-drive wind

power system in different frequency response stages was adjusted by comprehensively considering the fan speed，

frequency deviation，and frequency rate of convergence，to realize the active frequency support and flexible

frequency modulation exit of the wind power system. A simulation model of a direct-drive wind power system was

established in Matlab/Simulink to verify the effectiveness of the proposed control strategy.

      Key words：continuous drop in grid frequency；direct-drive wind power system；droop coefficient；primary

frequency regulation control