PCC dq-Frame Based Power Loop Modeling and Stability Analysis of Grid-Following Converter

For large-scale renewable energy power generation plants, the impedance model based stability analysis method, which describes the dynamic characteristics between instantaneous voltage and current of the converter terminal, has the advantages of clear physical meaning and simple model for system stability analysis. However, the impedance model generally takes the converter terminal as the modeling benchmark, which requires coordinate conversion due to the feeder dynamics and thus is difficult to realize unified modeling in complex systems. Besides, people in power system community pay more attention to the dynamics of power rather than voltage and current. Therefore, in this paper, a power loop model of grid-following (GFL) converters based on the PCC dq-frame is proposed, which can simple the modeling and analysis of the large-scale renewable energy power generation plants. Furthermore, the Nyquist criterion are adopted to analysis the self-stability of GFL converters by the proposed power loop model. Simulation and experimental results are finally provided to verify the feasibility and effectiveness of the proposed model and the stability analysis.