Control of variable power low voltage ride-through and imbalance under abnormal voltage conditions in grid-tied photovoltaic inverters

Grid connection is a key aspect of the stable operation of PV systems, and traditional grid connection methods rely on PV inverters. Existing power electronic hardware still faces challenges in providing sufficient transient support while maintaining stable power output under grid fault conditions. To address this, this paper proposes an improved fault ride-through control strategy for PV inverters. First, by adjusting the PV cell power tracking trajectory, the voltage at the battery end is effectively reduced, minimizing the generation of excess energy, thereby avoiding Direct Current (DC) bus overvoltage and grid current overcurrent, and achieving power balance on both sides of the inverter. Secondly, a current reference generator is used, combined with the inverter control algorithm and positive–negative sequence current inner loop control, to calculate current commands, achieving current balance and power stability. Then, a quantitative relationship between the power reference setpoint and current peak threshold is established through the power reference generator, guiding the inverter’s power reference setting under unbalanced voltage conditions. Finally, simulation verification is conducted based on the Rtlab platform. This strategy effectively improves the stability and reliability of PV inverters under grid fault conditions.