Enhanced Low-Voltage Ride-Through Capability of Grid-Interfaced Three Phase Solar PV Power Plant

This paper presents a low-voltage ride-through (LVRT) strategy tailored to meet Indian grid code requirements, addressing a critical aspect of integrating photovoltaic (PV) systems with the electrical grid. Different countries have specific grid codes defining acceptable active and reactive power injection levels during balanced and unbalanced voltage sags. During LVRT events, the proposed two-stage grid-connected solar power production system (SPPS) remains connected to the grid. The inverter injects reactive power according to Grid Compliance standards, thereby restoring the voltage profile. The system efficiently operates during symmetrical and asymmetrical grid faults by using positive and negative sequence vector current components to manage the grid-connected solar inverter. The proposed approach utilizes a dual-loop current control mechanism, ensuring inverter over-current protection within a double synchronous reference frame and reducing active power oscillations. The outer loop regulates the DC-link voltage, while the inner loop manages current dynamics. This method mitigates real power and DC-link voltage fluctuations, ensuring smoother operation. The LVRT control approach is validated through simulation results using MATLAB/Simulink, demonstrating the performance of a 100 KW double-stage grid-interfaced solar photovoltaic system during asymmetrical voltage sags.