Modeling and Dynamic Stability Analysis of the Grid-Following Inverter Integrated with Photovoltaics

The power transfer capacity of transmission lines is limited by the stability of the power system. In addition, the dynamics of photovoltaic (PV) integration through the grid-following inverter (GFI) affects the stability limits, which are not well studied in the literature. This article, therefore, focuses on the stability-constrained power transfer capabilities of transmission lines with single-phase PV-GFI integration. An adaptive tuning method is proposed based on the Lyapunov function (LF) analysis that increases the power transfer capability limit. Outer and inner control loop parameters are considered as candidates for the proposed method. The proposed tuning law is not affected by the active and reactive power requirements, low-voltage or overvoltage ride-through, network impedance, and load changes. In addition, an active damping method using a capacitor voltage feedback loop is proposed to eliminate the effect of resonance with improved power quality. The proposed method is validated through simulation and experimental verification for various test scenarios, such as sudden changes in solar irradiance, dynamic load changes, network parameter variation, and grid voltage sag-swell conditions. The proposed tuning method achieves an enhanced power transfer capacity limit compared with the existing method.