Equivalent Circuit Model of Grid-Forming Converters With Circular Current Limiter for Transient Stability Analysis

This letter develops an equivalent circuit model of a grid-forming (GFM) converter with a circular current limiter and analyzes its transient stability. It is revealed that the inner control loop can be simplified as a voltage source behind an equivalent resistor. Based on the developed model, theoretical analysis and experimental tests demonstrate that the transient stability of a P - f droop-controlled GFM converter with the circular current limiter can be assured whenever there exist stable equilibrium points.

Automated summary

This letter presents an equivalent circuit model for a grid-forming converter with a circular current limiter and investigates its transient stability. It is found that the inner control loop can be simplified as a voltage source behind an equivalent resistor. Theoretical analysis and experimental tests based on the proposed model demonstrate that the transient stability of a P - f droop-controlled grid-forming converter with the circular current limiter can be guaranteed when stable equilibrium points exist.