Strong Signals / Issue 01 / November 2026
How your PRC-029 studies broke
Every PRC-029-2 study hit the same ten problems. Plus SPP's model manual, a CIGRE result that should worry you, and 3,800 MW that left the grid.
What was your biggest PRC-029-2 blocker?
GridStrong logged every model issue that slowed down a PRC-029-2 ride-through assessment, in PSS/E and in PSCAD, across a portfolio of plants. The issues fell into ten families. Plant data that conflicted or was missing caused 31% of them, three times the next family, and it turned up on 100% of projects.
Sound familiar? Email us at newsletter@news.gridstrong.ai and tell us which of the ten you have hit.
In this issue
- SPP's model manual is in force: every interconnection customer now owes four models and 67 tests.
- CIGRE Energy Forum: the same plant passes or trips depending on how the PRC-029-2 profile is applied.
- SMA Grid Integration Summit: the panel deck on 3,800 MW of data center load that left the grid with nothing failing.
- The new gridstrong.ai, with a free PRC-028-1 study for one plant.
- Where to find the team at RE+ in Las Vegas next week.
Deep dive
What breaks PRC-029-2 ride-through models
Lessons from a portfolio of PSS/E and PSCAD assessments, by Mehdi Rezvani, Principal Engineer, Power Systems Studies
- A validated MOD-026-2 model is not a ride-through model. It was fitted to reference steps, not to faults, and it can pass MOD-026-2 and still misbehave in the PRC-029-2 profile.
- Point of measurement matters. At full lagging or leading dispatch, terminal voltage can sit 5 to 10% away from the voltage at the main transformer's high side, which is where PRC-029-2 measures.
- OEM model delivery was the second family at 11%: late models, wrong versions, and PSS/E and PSCAD models of the same inverter that did not agree with each other.
The article covers how each family was resolved, how to keep PSS/E and PSCAD aligned, what it means for Category 2 plants, and fourteen practical suggestions for the next study.
Compliance Watch
Four models. 67 tests. One verdict.
- Rule: SPP Generating Facilities Modeling Requirements Manual V1.0 (RR764, FERC docket ER26-3625)
- Status: Accepted by FERC on November 5, 2026
- Effective: October 26, 2026
- Applies to: Every interconnection request submitted on or after October 26, 2026, including Surplus, Replacement, Modification, Interim Availability and Affected System requests
- Scope: Four model sets per site, 67 tests, one pass or fail
SPP planners will now get models that are validated, benchmarked and consistent across tools, in line with FERC Order No. 901 and IEEE 2800-2022. For interconnection customers it is a new bar, and it is already here. Every model package now has to:
- Deliver four site-specific model sets: standard library, PSS/E UDM, TSAT UDM and PSCAD.
- Run all 67 tests and pass every required one.
- Overlay all four models on the same axes and justify every significant mismatch.
- Resubmit at the Interconnection Request, after the Decision Point, at GIA signing, and on as-built data 60 days before COD.
It is not only the next queue. Any Surplus, Replacement, Modification, Interim Availability or Affected System request submitted on or after October 26, 2026 falls under the manual today.
See how SPP compares with the other RTOs
GridStrong's SPP Model Quality Tests module
Research / CIGRE Energy Forum 2026, Calgary
Same plant, same settings, different results.
Pass, trip, pass. The plant did not change and neither did its settings; only the way the test was applied did. Iman Kaffashan presented GridStrong's comparative assessment of voltage ride-through test profiles in PRC-029-2 at the CIGRE Energy Forum 2026 in Calgary. Using EMT simulation of a 200 MW wind plant, the team compared three ways of applying the PRC-029-2 voltage profile:
- Case A: Isolated single-fault tests with full recovery. Result: Pass.
- Case B: Sequential steps with no recovery. Result: Trip.
- Case C: Sequential steps with a 10-second recovery. Result: Pass.
The test methodology can decide the compliance result. The paper calls for a clearer profile definition in PRC-029, or guidance coordinated with IEEE 2800-2022.
Co-authors: Poria Astero (GridStrong), Maryam Torabi and Sifat Amin (PSC Consulting). All GridStrong talks and papers
From the podium / SMA Grid Integration Summit 2026
The latest on getting data centers online faster
Northern Virginia lost about 1,500 MW of data center load in 2024 and about 3,800 MW in 2026, and every piece of equipment did exactly what it was set to do. ERCOT counted 26 of these events between 2023 and 2025. Tom Scaramellino moderated the large-load panel at the SMA Grid Integration Summit 2026 with Todd Hillman (MISO) and Erik Ela (ESIG): why the inverter-based resource playbook does not transfer cleanly to load, the two regulatory tracks converging on the same facility, and where each region stands.
GridStrong for data centers and large loads
Where to find us
RE+ 2026, Las Vegas
Two sessions on Wednesday, November 18, both at the Las Vegas Convention Center.
- Wed Nov 18, 11:30 am to 12:15 pm PT. Dispatches Live: Accelerating Large Load Interconnections, From Modeling to Energy Management. Tom Scaramellino with Ahren Lieth (FlexGen) and Frank Berring (SMA). W307 / W308.
- Wed Nov 18, 1:00 to 3:00 pm PT. SEIA: Meet the Software Experts, Managing IBR Assets and Achieving Regulatory Compliance. Tom Scaramellino, CEO. Room 223, West Hall.
Also from GridStrong
Every standard your plant answers to, requirement by requirement.
The new gridstrong.ai is live. The Standards Help Center takes each NERC, ERCOT and MISO requirement for inverter-based resources one at a time: who it applies to, the dates, what the requirement says, the evidence an auditor expects, and a free template procedure. Next to it, a Compliance Calendar of every effective and compliance date that matters, and Client Guidance, short engineer-written briefs on the rules clients ask about most, free, no sign-up.
Standards Help Center · Compliance Calendar · Client Guidance
One plant. One PRC-028-1 study. No invoice.
A NERC PRC-028-1 disturbance monitoring assessment for one plant, at no cost and with no obligation. Sign the NDA, send every file you have for the plant, and the initial results are in the Dashboard within 72 hours; the signed, engineer-reviewed assessment follows in under a week.
What was your biggest PRC-029-2 blocker?
Plant data, OEM models, a validated MOD-026-2 model that failed the fault, the point of measurement? Email us at newsletter@news.gridstrong.ai and tell us which of the ten families hit you. We read every reply, and the answers shape the next issue.
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