A Low-Voltage Ride-Through Strategy for Two-Stage PV Inverter with DSOGI Phase-Locked Loop

The low-lovage ride-through (LVRT) of inverters plays a significant role in power system stability. In this paper, a LVRT strategy is proposed and validated by building a two-stage PV grid-connected inverter model. The proposed model is designed to manage the MPPT link and adjust the active output, which ensures that the DC bus voltage remains stable. Additionally, the model is capable of detecting voltage dips and automatically adjusting its control structure. This automatic adjustment is crucial for providing reactive power support when a fault occurs. A voltage feed-forward in the current loop is used to counteract the effect of grid voltage on the current during grid faults. Besides, this paper employs a dual SOGI-based PLL for positive and negative sequence separation, enabling rapid and accurate grid signal tracking and measurement during faults. A case study is carried out to verify the proposed approach.