Comparison of the Consistency and Diversity of Small Signal Analysis of Grid-Connected System between Grid-Forming Converter and Grid-Following Converter

The grid-forming converter and grid-following converter are widely used in the grid connection of new energy generation units. Consistency and diversity exist in the synchronization control, inner loop control and outer loop control of the two types of converters. The characteristics of the converters can be better investigated by analyzing the consistency of the structure of the two. Due to the different control structures of two converters, the characteristics of them are different. A series of new interaction problems arise when different converters are connected to the network. The analysis of the difference between the two characteristics is conducive to the study of the model characteristics of future large-scale hybrid converters integrated into the power grid. In this paper, the small signal model of merging grid-forming converter and grid-following converter into infinite power grid is established by using the state space method. The eigenvalue of the system can be analyzed by changing the parameters of the internal control link and the external line. The conclusion that there is consistency and diversity between the grid-forming converter and the grid-following converter in the aspects of internal control and the influence of external power grid is verified by comparing the frequency domain analysis results with the time domain simulation results.