Under the dual-carbon target, combining a large number of abandoned mines with AC excitation pumped storage power stations, can not only solve the problem of reuse of abandoned mines, but also provide support for the new power system. The control parameters of the traditional integrated inertia frequency modulation control strategy inertia ring and droop ring are fixed, resulting in the insufficient ability of ACEPSU (AC excitation pumped storage unit) to participate in power grid frequency modulation. Based on this, this article proposes an improved integrated inertial frequency modulation control strategy based on variable gain coefficient inertia ring and droop ring time-sharing participation regulation. The improved control strategy introduces the ACEPSU speed variable and the ACEPSU standby power variable into the gain parameters of the inertia ring and the droop ring respectively, and puts forward the corresponding gain parameter setting method. Meanwhile, the speed over -limit protection control is added to prevent the unit stall during the frequency modulation process. Finally, the simulation model of the three-engine power system is established for comparison and verification.