Fault Behavior of Inverter-based Resources: A Comparative Study for Grid-forming and Grid-following Control Paradigms

In this paper, we compare the performance of grid-forming (GFM) and grid-following (GFL) inverters during unbalanced grid faults. By performing an exhaustive time-domain electromagnetic transient (EMT) simulation study of an all-inverter network, we compute a variety of transient and steady-state fault signatures including peak current, transient time, sequence voltages, and harmonic distortion with computational methods spanning wavelet, Fourier, and Forstescue transforms. Simulation results quantitatively establish that: i) GFM control architectures offer superior transient and steady-state fault performance compared to GFL architectures, ii) the performance of the virtual-impedance current limiter in GFM inverters offers better performance compared to current-reference saturation limiter, and iii) the specific choice of primary-control method has minimal impact on fault behavior of GFM inverters.