Grid-Forming Inverters Can't Interconnect at Scale Because Standards Were Written for the Technology They're Replacing

As coal and gas plants retire, the grid loses synchronous machines that provide voltage formation, inertia, and fault current — functions essential to grid stability. Grid-forming (GFM) inverters can replicate these functions, but the two governing interconnection standards — IEEE 1547-2018 (distribution) and IEEE 2800-2022 (transmission) — were designed for grid-following (GFL) inverters that depend on the grid they're supposed to be replacing. NREL/UNIFI testing found that GFM inverters respond faster than IEEE 1547 minimum allowable ranges, and that test procedures required modifications to the GFM model that wouldn't be needed for GFL. The standards contain "inadvertent barriers" — requirements that make physical sense for GFL but block GFM deployment.

The grid needs GFM capability to maintain stability as renewable penetration increases — this is the consensus view of DOE, NREL, EPRI, and major utilities. But GFM technology cannot be interconnected at scale until standards are revised, creating a circular problem: utilities need GFM for stability as fossil generation retires, but the standards governing interconnection encode the assumptions of the fossil-plus-GFL paradigm. The DER interconnection backlog across the U.S. is already severe (covered in existing brief `energy-grid-connection-queue-bottleneck`); adding standards uncertainty for GFM compounds queue delays. DOE created the Essential Grid Operations from Solar (EOS) project specifically to address this.

The UNIFI Consortium published a preliminary gap analysis (NREL/TP-88609, 2024) testing generic GFM models against IEEE 1547 and 2800 requirements. They found specific test procedure failures: the frequency droop gain had to be changed to 20/5% to suppress active power oscillations — a modification specific to GFM that wouldn't be needed for GFL. A footnote in IEEE 1547 Table 24 permits faster response times than the minimum allowable range, but this is "not immediately obvious, creating a de facto barrier." DOE published GFM specifications (Version 1) as a reference, not a standard. The fundamental problem is structural: IEEE standards take years to revise (the 1547 revision from 2003 to 2018 took 15 years), and even after publication, certification testing (UL 1741 SA/SB) lags by another 1+ years. Meanwhile, GFM technology is needed now.

An accelerated, narrowly scoped amendment to IEEE 1547 and 2800 that explicitly accommodates GFM behavior — rather than a full revision cycle. This requires validated test procedures for GFM-specific characteristics: voltage source behavior, faster-than-minimum frequency response, and island-to-grid transition. The UL 1741 certification test procedure also needs a GFM-specific protocol. The UNIFI preliminary gap analysis identifies "many more tests still yet to be done" — completing this testing program would provide the technical basis for standards amendments.

A team could build a hardware-in-the-loop simulation of a GFM inverter connected to a simplified grid model and systematically test which IEEE 1547 requirements the GFM passes, fails, or triggers ambiguous results. This directly replicates and extends the UNIFI gap analysis at lower cost. A power systems simulation (e.g., in PSCAD or OpenDSS) comparing grid stability under GFL-only vs. mixed GFL/GFM scenarios would also produce useful data. Relevant disciplines: electrical/power engineering, control systems, simulation/modeling.