Abstract
The growing penetration of inverter-based resources (IBRs) in bulk power systems demands short-circuit models that capture both device-level dynamics and protection-relevant behaviors while remaining computationally efficient. Conventional voltage-source-behind-impedance models neglect control interactions, sequence coupling, and fault ride-through (FRT) behaviors, whereas electromagnetic transient (EMT) models, though accurate, are computationally intensive and lack interoperability in planning workflows. This paper presents a compact, parametric reduced-order model (ROM) for grid-following inverters that reproduces IBR fault current trajectories-including subtransient, transient, and steady-state phases-across a range of fault types, locations, and pre-fault operating points. The proposed model is tuned using detailed EMT simulations under multiple control configurations, including negative-sequence current control in the dq frame. Validation against EMT benchmarks demonstrates the ROM's ability to capture magnitude, phase, and oscillatory content within 1.5 cycles of fault inception, using a single parameter set for diverse fault scenarios. This capability makes the ROM suitable for protection studies, grid code compliance verification, and integration into planning-grade short-circuit tools.