With the gradual increase of photovoltaic permeability

the photovoltaic power generation system is urgently needed to participate actively grid frequency regulation. However

the present photovoltaic power generation system is connected to power grid by the maximum power tracking mode and does not possess active power frequency modulation ability. In view of above issue

a kind of active standby photovoltaic power generation system based on variable step power tracking is proposed. The variable step power tracking is used to make the system operate in the active standby mode. In case of grid frequency disturbance

the active power output of the photovoltaic array is adjusted by way of correcting capacitive voltage of DC side so to participate the primary frequency modulation. The improved droop control strategy for the grid-side inverter is adopted. The differential negative feedback virtual inertia control of angular frequency simulation rotor inertia of the capacitive capacitor energy storage characteristic at DC side are introduced to make up for the issue of insufficient primary frequency modulation output at the beginning of fault so to reduce the depth of frequency drop. It is verified by the simulation analysis that the proposed control strategy can provide much power support either at the dynamic action at the initial fault or during the primary frequency modulation

which can

to some extent

replace the frequency modulation effect of the synchronous generator.