Impact of Filter Inductance on Transient Synchronization Stability of Grid-Connected Systems with Grid-Following Converters Under Voltage Sag Faults

As renewable energy sources become more prevalent, maintaining the sustainable and reliable operation of power systems has become as a major challenge. Modern grid-connected converter systems are particularly prone to losing synchronization when encountering large disturbances, which is a huge threat to the stability of the power grid, which is mainly based on renewable energy. This paper studies the impact of filter inductors on the synchronous stability of grid-connected converter systems, hoping to help us better connect renewable energy to the power grid. First, the existing synchronization stability model of grid-following (GFL) converters is extended by incorporating filter inductance modeling. Based on this model, a mathematical relationship between the phase-locked loop’s (PLL) frequency deviation and the filter inductance at the moment of fault is established, and a predictive method for GFL frequency deviation considering filter inductance is proposed. Furthermore, the impact of filter inductance on synchronization stability is systematically investigated through two key indicators: power angle overshoot and critical fault voltage, revealing the variation trends of transient stability under different operating conditions. Finally, the analytical results are validated through Matlab/Simulink simulations, providing theoretical guidance for the design of sustainable and robust renewable energy grid integration strategies.