Frequency-domain small-signal stability analysis methods for grid-following converters systems— An overview

Frequency-domain small-signal stability analysis is essential to the integration of Grid-Following Converters (GFCs) into power systems. GFCs are Multiple-Input Multiple-Output (MIMO) systems. Thus, basic MIMO stability criteria can be directly applied with no model transformation. However, a MIMO model can be transformed in such a way that Single-Input Single-Output (SISO) stability criteria can be alternatively applied. Numerous stability analysis methods for GFCs systems have been developed over the last few years. However, how to choose appropriate models and stability analysis criteria for GFCs systems in different scenarios remains unclear. This article comprehensively reviews various stability analysis approaches for GFCs systems and provides a detailed comparison of the advantages and disadvantages of alternative MIMO and SISO stability analysis methods. Key findings reveal the discrepancy and equivalence of certain MIMO and SISO criteria, the efficiency of improved Generalized Nyquist Criterion methods in complex analysis, the effectiveness of advanced SISO models in capturing nuanced stability characteristics. The study further differentiates white-box and black-box models, demonstrating their respective strengths in GFCs stability assessment. Additionally, the paper identifies future trends and challenges for advanced multi-node GFCs systems stability methods, accurate subsystem partitioning, and reliable stability margin estimation for large-scale and black-box systems. These insights serve as a foundation for developing more robust and efficient stability analysis techniques, contributing to the enhancement of renewable energy integration.