In order to solve the problem of insufficient frequency regulation capacity caused by the large-scale grid-connected photovoltaic (PV) generation, the active power-frequency droop control strategy and virtual inertial control strategy are proposed for single-stage grid-connected PV generation for electromechanical transient analysis. By modifying the control structure of the inverter, PV generation actively gets involved in frequency regulation. Based on the relationship between unbalanced active power excitation and phase output response, the influence of control gain coefficient, time constant and phase-locked loop control bandwidth on the inertial characteristics of PV generation is analyzed. The simulation results indicate that the inverter can control the PV 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; in the dynamic process of frequency, the incremental power of PV generation induced by the dynamic action of the voltage vector of grid connection point is dependent on its virtual inertial control; the greater the gain of virtual inertial control, the smaller the time constant or the smaller the control bandwidth of the phase-locked loop, the greater the virtual inertia of PV generation, and the more supportive power can be provided in the dynamic process of frequency. This work is supported by National Natural Science Foundation of China (No. 51277024) and Science and Technology Project of State Grid Corporation of China (No. 5229DK17000W) “Research on Active Control Technology of Frequency and Voltage of PV Station Seconds Power Disturbance”.