Abstract: The virtual synchronous machine technology simulates the electromechanical transient characteristics of the traditional synchronous generator set, which makes the photovoltaic grid connected inverter have the inertia, damping, frequency and voltage adjustment of the synchronous unit. However, over-reliance on energy storage systems will inevitably affect traditional PV virtual synchronization technology applications in actual engineering, which will greatly increase the construction cost of PV system. In this paper, a reduced power virtual synchronous control strategy is proposed. By properly reducing the active power output of photovoltaic power supply making use of non-linear property of PV system output, the PV system can actively participate in the frequency response of power grid without additional energy storage unit. The simulation results verify the effectiveness and correctness of the proposed control strategy, which can provide a theoretical basis for large-scale PV connection and consumption.

Key words: PV system, primary frequency modulation, active power reserve, virtual synchronization generator