Keaton A. Wheeler

The rise of inverter-based distributed energy resources (IBRs) is reshaping global power system planning and operation. Unlike traditional rotating machines, IBRs lack physical characteristics and rely on control algorithms to support the grid during abnormal conditions. This is especially evident in mass-adopted distributed sources like rooftop residential-scale Distributed Energy Resources (DER), which are controlled to behave as constant current sources. Numerous jurisdictions already experience steady-state reverse flows at substations during periods of minimum load and maximum generation. However, the aggregation of IBRs exacerbates ground fault overvoltages (GFOV) at the transmission level, as they appear as open circuits in the zero and/or negative sequence networks. This paper analyzes the issue through electromagnetic transient (EMT) simulations, yielding chart-based screening guidelines. These guidelines can assist utilities in evaluating necessary retrofits for substations as more IBRs are adopted, particularly for small-scale IBRs that are interconnected with little to no rigorous analysis.

This paper presents an investigation into the use of superconducting fault current limiters (SFCLs) for microgrid integration into distribution networks and their associated protection systems. SFCLs are investigated for their suitability to prevent loss of coordination between the main distribution network's fuse and recloser protection infrastructure when microgrid integration is present. Additionally, SFCLs are investigated for their suitability in aiding internal microgrid overcurrent protection by assessing their capability of use for bidirectional short circuit current flow. The evaluation is demonstrated through use of the EMTP-RV software with a typical distribution network and microgrid as a test bench.

This paper investigates the effect of varying fault impedances in the context of Distributed Generation (DG) influences on distribution overcurrent protection infrastructure (specifically fuse-recloser protection). The assessment includes an investigation into a DG source integration evaluation method to determine the effects of varying fault impedances. The assessment and evaluation techniques used are demonstrated through time-domain simulations in the EMTP-RV software environment on a typical distribution network.