A New Paradigm in IBR Modeling for Power Flow and Short Circuit Analysis

Abstract: The fault characteristics of inverter-based resources (IBRs) are different from conventional synchronous generators. The fault response of IBRs is non-linear due to saturation states and mainly determined by fault ride through (FRT) strategies of the associated voltage source converter (VSC). This results in prohibitively large solution times for power flows considering these short circuit characteristics, especially when the power system states change fast due to uncertainty in IBR generations. To overcome this, a phasor-domain steady state (SS) short circuit (SC) solver for IBR dominated power systems is proposed in this paper, and subsequently the developed IBR models are incorporated with a novel Jacobian-based Power Flow (PF) solver. In this multiphase PF solver, any power system components can be modeled by considering their original non-linear or linear mathematical representations. Moreover, two novel FRT strategies are proposed to fully utilize the converter capacity and to comply with IEEE-2800 2022 std and German grid code. The results are compared with the Electromagnetic Transient (EMT) simulation on the IEEE 34 test network and the 120 kV EPRI benchmark system. The developed IBR sequence domain PF model demonstrates more accurate behavior compared to the classical IBR generator model. The error in calculating the short circuit current with the proposed SC solver is less than 3%, while achieving significant speed improvements of three order of magnitudes.