In order to solve the problem of insufficient frequency regulation capacity caused by the large-scale grid-connected photovoltaic generation, the active power-frequency droop control strategy and virtual inertial control strategy are proposed for double-stage grid-connected photovoltaic generation, the original control structure of the Boost converter or the grid-side inverter is changed, so that the photovoltaic generation can actively participate in the grid frequency regulation. The influence of the virtual inertial time constant and the Phase-Locked Loop (PLL) bandwidth on the virtual inertial control is analyzed. The virtual inertial characteristics of photovoltaic generation are analyzed based on the active power-phase motion model of photovoltaic generation and the frequency response model of the synchronous generator, and their influence on the dynamic characteristics of the system frequency is also analyzed. Simulation results indicate that both the Boost converter and the grid-side inverter can control the photovoltaic array to increase or decrease the active power generated according to the set droop curve, so as to suppress the drop or rise of the grid frequency; larger virtual inertial time constant or smaller PLL bandwidth can lead to larger virtual inertia of photovoltaic generation and more power in the frequency dynamic process. This work is supported by National Natural Science Foundation of China (No.51277024) and Science and Technology Project of the Headquarter of State Grid Corporation of China (No. 5229DK17000W).