To solve the coupling problem of source-load fluctuation and frequency security risk in power systems with high proportion of new energy

this paper proposes a day-ahead dispatching mode that considers security constraints

fine segmentation

and collaborative optimization of peak shaving and frequency regulation. Firstly

based on the analysis of the peak shaving and frequency regulation processes in power grids with high renewable penetration

a fine segmentation and collaborative optimization method for generator unit reserve capacity is proposed to address risks in steady-state power imbalance

transient frequency over-limit

and quasi-steady- state frequency recovery. Secondly

taking into account not only the system's peak shaving and frequency regulation reserve demand and primary frequency response ability

but also the load inertia characteristics of the generator unit under different working conditions

a day-ahead dispatching model for active power frequency security in low-inertia power grids is proposed. Then

an automatic generation control (AGC) re-regulation model for reserve capacity is further established to meet the fast recovery requirement of quasi-steady-state frequency. Finally

the improved IEEE 39-bus system is employed to verify the accuracy of the model in characterizing the power system's reserve capacity demand and demonstrate the proposed model's advantages in suppressing active power frequency security risks.