LVRT Control Strategy for Photovoltaic Grid-Connected Inverter Based on Improved Virtual Impedance

The traditional LVRT control strategy does not consider the poor dynamic performance of the system and the increase of current harmonics during the grid fault. Therefore, in order to suppress the grid-connected current harmonics caused by grid voltage disturbance and improve the dynamic performance of the system, this paper studies an improved virtual impedance low voltage ride-through control strategy, which replaces the parasitic resistance on the traditional LCL filter by replacing the virtual impedance, and feeds back the real-time values of capacitance current and inverter current to the control loop through feedforward and feedback respectively, and autonomously adjusts the equivalent damping, so as to suppress the current harmonics during the grid fault and improve the dynamic performance of the system on the basis of cost saving.