Transient Power Angle Stability Analysis of Grid-Forming Converters Under Resistive Short-Circuit Faults

Abstract

This paper examines the transient power-angle stability of grid-forming converters (GFMs) subjected to grid faults. Existing studies commonly simplify the network as a purely inductive line and use ideal fault assumptions, which makes it difficult to describe how practical fault conditions influence power transmission and stability. A fault analytical model that includes line resistance is therefore constructed, and a closed-form Pe-delta relationship is obtained with offset, amplitude, and phase-shift components. Fault position, transition resistance, the line impedance ratio, and short-circuit ratio are incorporated into the model. On the basis of the equal-area criterion, the transient instability process of GFMs under different fault types is analyzed. MATLAB/Simulink results verify both the proposed expression and the corresponding stability mechanism. A further scan of the transient stability region shows that resistance-grounded and reactance-grounded faults present different stability distributions when the grid and fault parameters vary.