The April 2025 Planning Working Group (PLWG) meeting covered a range of impactful topics central to grid planning, generator interconnection standards, and resiliency in ERCOT’s evolving energy landscape. Below is a breakdown of the key issues discussed, the objectives behind them, and the anticipated next steps.
PGRR120 – SSO Risk Reduction for Generator Interconnection
ERCOT presented updates to the PGRR120 revision, focusing on reducing, not eliminating, the risk of sub-synchronous oscillation (SSO) for new generator interconnections. Notable changes include:
- A shift to using SGIA execution dates for grandfathering purposes to simplify the rule language.
- Clarifications that the updates apply only to transmission-connected generation, not distribution.
- A title change from “risk prevention” to “risk reduction,” as recommended by AEP, to more accurately reflect the proposal’s intent.
- Removal of the phrase “subject to cancellation” to allow generators flexibility in addressing identified risks.
- Updates to language describing study contingencies and technical references, along with refinements to the security screening study process.
Stakeholder Perspective: Lone Star voiced concern over the rigidity of the grandfathering cutoff and argued for a more tailored approach. ERCOT emphasized the proposal does not ban interconnections, but rather shifts the burden of mitigation (e.g., funding transmission upgrades) to the generator when risks are identified.
Next Steps: Lone Star will submit formal comments before the May 15 meeting. The item will be revisited with broader feedback.
Smart Wires Technology Review
Smart Wires presented their modular static synchronous series compensator (M-SSSC) as a flexible, real-time solution for mitigating SSO and SSR. Key highlights include:
- The device can both increase and decrease line impedance to optimize power flow.
- It replicates an ideal sinusoidal waveform, offering a smoother integration than traditional series capacitors.
- M-SSSC is particularly well-suited for inverter-based resources (IBRs), with minimal risk of harmful interaction.
A case study from Latin America and a project in New York demonstrated its effectiveness and cost range ($5–$15 million depending on scale and scope).
Takeaway: While promising, stakeholders agreed SSO studies are still essential. The proposal to reference this technology in PGRR120 will be evaluated further before final decisions.
PGRR122 – Reliability Criteria for Loss of Load
ERCOT is working to establish a planning-level criterion for acceptable load loss during interconnection studies—an issue increasingly relevant with the rise of large load additions.
Discussion Points:
- ERCOT is preparing a loss of load study to be presented at the May DWG meeting, which will inform the final limits.
- Stakeholders voiced concern over whether retrofits would be required for existing or expanding loads.
- The proposal currently applies only to large load interconnection studies, not planning studies in general.
Next Steps: Stakeholders await study results before progressing. More clarity is needed on how this aligns with other planning standards and contingency mitigation strategies.
NPRR1272 – Voltage Support Obligations for Private Use Networks
The conversation centered around how reactive power obligations are calculated when load and generation are colocated. ERCOT proposed a self-limiting approach to ensure fairness in system support expectations.
Key Issues Raised:
- Oxy expressed that the self-limiting model is not viable for their situation.
- ERCOT acknowledged that colocated loads may diminish net reactive support available to the system, complicating equitable enforcement.
Next Steps: Oxy plans to submit additional comments. There was debate about whether the item should stay with PLWG or move to the WMS due to cost implications.
PGRR124 – ESR Maintenance Exception for Modifications
Although representatives from Tesla and Eric Goff were unavailable, previous discussions at DWG touched on:
- Whether the PGRR109 expedited process could be used for Megapack replacements.
- The potential to simplify maintenance-related modifications to ESRs (Energy Storage Resources) without triggering full reviews.
Next Steps: Tesla will conduct internal reviews and follow up with ERCOT.
NPRR1274 – Capital Cost Threshold Adjustments for RPG Projects
ERCOT proposed revising the RPG project cost thresholds upwards by 35% to account for cumulative inflation since 2018.
Stakeholder Input:
- Oncor supported the increase but noted that real-world costs—especially for land, specialty equipment, and labor—have risen faster than inflation.
- Oncor also observed a recent spike in EIR (Early Identification of Reliability) filings due to outdated cost thresholds.
Next Steps: Stakeholders will submit written feedback before the next meeting. The item will be tabled until then.
Future NPRR – Resiliency Criteria for Transmission Project Evaluation
ERCOT is working to implement SB1281 by developing a multi-value evaluation framework for transmission projects related to resiliency. This includes:
- Evaluating thermal and voltage loading issues during extreme weather, based on biennial grid resiliency assessments.
- Requiring TSPs to justify projects based on these findings, using defined thresholds for overloads and equipment limits.
Open Questions: Stakeholders requested clarity on threshold definitions, voltage limit interpretations, and how different TSP practices will be aligned.
Next Steps: Continued development of criteria for integration into Section 3.11.2 of ERCOT protocols.
Open Action Items
The group briefly reviewed pending action items, including language consistency in the Planning Guide (e.g., standardizing use of “load” vs. “Load”).
In Summary
This month’s PLWG meeting showcased the delicate balancing act between innovation, operational clarity, and stakeholder alignment. As ERCOT adapts its planning and interconnection processes to meet reliability needs and policy mandates, collaboration across stakeholders remains crucial.
Upcoming Milestones:
Comment submissions and further discussion across NPRR1272, NPRR1274, and other proposals.
May 15 DWG meeting: Expected presentations on PGRR122 loss of load criteria and formal comments on PGRR120.
Full meeting materials for the April 29 session can be found here.
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