1.School of Electrical Engineering, Southeast University, Nanjing 210096, China;2.Economic and Technological Research Institute of State Grid Jiangsu Electric Power Co., Ltd., Nanjing 210008, China

The frequency security problem caused by the weak inertia characteristic of the new power system is essentially the decrease of the equivalent inertia. Therefore, the quantitative estimation of the minimum inertia requirement of the new power system has become an urgent engineering problem to be solved. To this end, an evaluation method for the minimum inertia requirement is proposed. Firstly, a spatial frequency response (SFR) model of the multi-machine system is proposed considering thermal power units, wind turbines, and asynchronous machines participating in frequency regulation, and based on the quantitative analysis of the system frequency characteristics, an equivalent inertia mathematical model for power systems is established considering the virtual inertia characteristics of wind turbines and asynchronous motors. Secondly, taking the initial rate of change of frequency (RoCoF) and the maximum frequency deviation as the frequency security constraints, the minimum inertia requirement of power systems is evaluated based on the frequency response model. Finally, the effectiveness of the proposed method is verified on MATLAB/Simulink and PSD/BPA simulation platforms.