Small-Signal Stability Analysis of Grid-Connected System for Renewable Energy Based on Network Node Impedance Modelling

As distributed renewable energy is integrated into the power grid, the issue of small-signal stability arising from the interaction between the grid-connected converters and the grid-side impedance cannot be overlooked. However, when multiple converters for renewable energy are interconnected, the system topology becomes complex, making it difficult to delineate the source and grid subsystems. This poses challenges for analyzing the interactive stability among the control loops of grid-connected converters and network impedance. To address this, this article establishes a small-signal impedance model for a grid-connected system. By deriving the transfer functions of individual control loops through the control block diagram, the stability influencing factors for specific control parameters can be analyzed. Furthermore, a stability analysis method for systems with multiple grid-connected converters based on a network node impedance model is proposed. This method enables the determination of stability for grid-connected converters connected at different node locations, providing a theoretical reference for the stability analysis of grid-connected systems.