Comparative Stability Study of Grid-Following and Grid-Forming Converters in Current Control Timescale

Oscillations in current control (CC) timescale caused by the large-scale integration of voltage-source converters (VSCs) have gained more and more attention from both academy and industry. In view of this problem, a comparative study is conducted to investigate the stability difference between gridfollowing (GFL) and grid-forming (GFM) converters in CC timescale. Firstly, the unified linearized model of GFL and GFM converters is established. Secondly, the impact paths of other control loops on the current control loop are extracted based on the proposed model. Thirdly, the characteristics of the corresponding paths in GFL and GFM converter are studied. By comparing the impact of the corresponding paths on the current control loop, the root cause of the stability difference between GFL and GFM in CC timescale is revealed. All results are verified through time-domain simulations.