Stability Analysis of Clustered Converter Systems with Parallel Structure

As we all know that integrating large-scale converters into power systems can lead to converter-driven oscillations. However, traditional research typically focuses on grid-forming control (GFL) widely used in renewable energy generation, while there is relatively less research on the impact of grid-forming control (GFM) on the dynamic characteristics of converter-based systems, which can lead to reduced small-signal stability. Moreover, there are significant differences in the construction of GFM and GFL, and the conclusions drawn from studying GFL control are not entirely applicable to GFM control. Therefore, it is necessary to conduct in-depth research on the dynamic characteristics and instability risks of large-scale parallel structures with grid-forming control of voltage-source converters (VSCs). This paper first studies the small-signal stability of a single converter grid-connected system and then extends it to a cluster of parallel converters using equivalent theory. The paper provides a detailed derivation of the theoretical method for system stability analysis and verifies the results using MATLAB simulation, ensuring the validity of the conclusions. This has significant implications for the operation of actual power systems.