On October 16, 2025, MISO’s Interconnection Process Working Group (IPWG) convened to advance reforms aimed at reducing study timelines, improving model quality, and clarifying interconnection cost responsibilities. The discussion focused on several major topics; including MISO queue reform improvements, IBR modeling enhancements, and MISO tariff updates, all intended to make interconnection more predictable and reliable. Below is an overview of the meeting’s key topics and discussions.
MISO Queue Reform and DPP Cycle Update
A central topic was progress on generator interconnection queue reform. The upcoming Definitive Planning Phase (DPP) 2025 study cycle will roll out updated schedules and requirements to improve queue efficiency. MISO aims to reduce delays caused by restudies and withdrawals by enforcing earlier milestone compliance and higher-quality data submissions. These changes are designed to provide developers with greater certainty and shorten the interconnection process from study to execution.
IBR Modeling Enhancements and Performance
Much of the meeting centered on inverter-based resource modeling and conformance. MISO outlined updates to its interconnection business-practice manual, which will now require detailed model submissions and standardized validation procedures at the GIA stage. The new requirements will apply to both PSSE user-defined models and electromagnetic transient (EMT) cases, ensuring that project data accurately represents real-world equipment behavior.
Key updates include:
- Implementation starting with the 2025–2026 DPP cycles
- Parameter verification and validation now mandatory for commissioning
- Transmission owners to have expanded access to review model data and results
- Continuous model updates under MOD-032 following project energization
These updates reflect MISO’s goal of improving system reliability by ensuring all new resources perform as expected under both normal and stressed grid conditions.
MISO Tariff Updates and Business Practice Manual
MISO also discussed updates to its tariff attachments and business-practice manuals to align with current queue needs. Revisions include improvements to merchant HVDC processes, surplus interconnections, and replacement interconnection procedures. The updated tariff will establish clearer cost allocation rules and strengthen requirements for readiness milestones.
Additionally, an engineering-study rate adjustment from $300 to $360 per hour will take effect beginning November 1, 2025. The goal is to better reflect the cost of staff time and technical analysis while maintaining transparency for developers.
Management Plan and Stakeholder Process
The updated IPWG Management Plan clarified the group’s objectives — including its advisory role in MISO’s generator interconnection processes, tariff changes, and business-practice manual revisions. Key administrative points included leadership elections for 2026 and deliverables scheduled for the next quarter, such as BPM finalization and stakeholder workshops on modeling tools and cost estimation.
Implications for MISO Developers and Grid Stakeholders
For developers and grid participants, this meeting reinforced several key trends:
- Interconnection readiness standards are rising, particularly for IBR modeling and validation.
- Queue processing will accelerate only for projects that meet these higher data and milestone requirements.
- Cost allocation and tariff updates aim to improve transparency for interconnection customers.
- MISO is introducing new modeling tools and verification steps to enhance accuracy and consistency across studies.
Developers should ensure project data, site control, and modeling packages meet the new standards to avoid delays and additional study costs.
At ZEG, we help renewable developers, utilities, and grid stakeholders navigate MISO’s evolving interconnection landscape. Our experts support readiness evaluations, dynamic model validation, and grid performance assessments to ensure projects meet technical and regulatory expectations.
Contact ZEG to align your project planning, modeling, and timelines with MISO’s latest reforms and accelerate your path to interconnection success.
For more on the MISO queue reform, IBR modeling enhancements, and MISO tariff updates, view MISO IPWG meeting materials here.
