Small-signal stability analysis of energy island type systems considering parallel operation of grid-following and grid-forming converters

This paper explores the damping effect of a grid-forming (GFM) converter on the small-signal stability of a grid-following (GFL) converter during weak grid configurations. The paralleled operation of GFL and GFM converters is considered in this work. It reveals that the stabilising effect of the GFM converter is proportional with its active power production, and the theoretical upper limit to this stabilising effect is set by the steady-state stability limit of the GFM converter. Electromagnetic transient simulations verify the small-signal stability analysis and the theoretical findings.