A Systematic Framework for Tuning Open-Source Multifunctional IBR Models to Emulate OEM Black-Box Fault Dynamics

The proliferation of inverter-based resources (IBRs) in modern power systems introduces fault characteristics that substantially differ from those of synchronous machines, posing challenges to conventional protection schemes. Although open-source generic IBR models provide full control transparency and tunability, their fault responses often diverge from trusted original equipment manufacturer (OEM) black-box models-particularly from the perspective of protection relays that rely on specific current magnitude, phase, and sequence component dynamics. Tuning the open-source generic IBR ensures its fault response matches the OEM black-box model, enabling protection engineers to design relay logic using the tuned open-source IBR model as a substitute for the OEM black-box model. This paper proposes a systematic framework for tuning open-source, multifunctional generic IBR models to emulate OEM-equivalent fault dynamics as observed by protection relay elements. The framework introduces structured guidelines for adjusting key parameters of inner control loops and current limiters to align the fault current magnitude, sequence content, and phase trajectories with those of OEM models across diverse fault types and locations. The tuned model's fidelity is validated through comparative analysis with an OEM black-box reference, assessing both the fault response and the operation of multiple relay functions-including distance, directional, and fault identification elements-adapted from a commercial protective relay. The results demonstrate that the tuned generic model can trigger relay decision logic that is identical or nearly identical to that of the OEM model, enabling intellectual property-compliant fault studies that directly inform protection design for IBR-rich grids.