Transient Stability Analysis of Grid-Connected Converter with Considering DC-Link Dynamics

Massive renewable energy is connected to the power grid though the grid-following (GFL) converter. The DC-link voltage fluctuates easily when experiencing the challenges, such as grid voltage disturbances, load fluctuation. However, many studies ignore the influence of the DC-link voltage dynamics on the GFL converter. In this paper, the dynamic active current caused by the DC-link voltage dynamics is analyzed for the transient stability of the GFL converter. The dynamic active current would introduce an extra negative damping term in the phase-locked loop (PLL). The estimated domain of attraction (DOA) is obtained though energy function and Lyapunov direct method. Finally, simulation results and experimental results verify the effectiveness of the theoretical analysis.