Most of the traditional photovoltaic power generation systems are connected to power grid by the maximum power tracking mode and do not have the frequency modulation capability by adjusting active power. However

the photovoltaic virtual synchronous generator(PV-VSG)that is modified by them are mostly equipped with energy storage to realize the virtual synchronization function

but the energy storage equipment is too expensive

and the main circuit transformation cost is large. To solve the problems above

a PV-VSG control strategy is proposed based on power tracking of variable step in active power reserve mode saves transformation cost by realizing virtual synchronization function through active power reserve mode without transforming the main circuit of traditional centralized photovoltaic inverter. The proposed method overcomes the incapable of compatibility and stability for the tracking method of fixed step

enables the PV-VSG to provide inertial and damping support control quickly and accurately. Simulation results verify the effectiveness of the proposed control strategy.