Author: Faizan Hassan Hajam
Midcontinent Independent System Operator (MISO), the first Federal Energy Regulatory Commission (FERC)-approved regional transmission organization (RTO) in the USA, is an independent, non-profit entity responsible for managing and planning the generation and transmission of high-voltage electricity across its territory reliably and cost-effectively. MISO’s operational region includes all or parts of 15 Midwestern and Southern US states (Arkansas, Illinois, Indiana, Iowa, Kentucky, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Montana, North Dakota, South Dakota, Texas, and Wisconsin) and the Canadian province of Manitoba.
Overview of the MISO Generation Interconnection Process
The Generation Interconnection (GI) process evaluates and approves the addition of new energy sources to the MISO-controlled transmission system. It also manages the retirement decisions of generators to ensure sufficient incoming energy to replace phased-out sources. The GI process outlines the steps an interconnection customer and MISO take to move interconnection requests through the interconnection queue, potentially resulting in an interconnection agreement that allows the customer to connect generation to the MISO grid. The application process for GI comprises the following phases:
1. Pre-Queue
2. Application Submission
3. Application Review
4. Definitive Planning Phases (DPPs)
5. Interconnection Agreement
1. Pre-Queue Phase – This phase includes an overview, timeline, and expectations pertaining to the output of the GI process. MISO offers regular information sessions to demonstrate the queue process and requirements throughout the GI-process phases. Moreover, potential customers can request ad-hoc meetings with MISO and the associated transmission owner (TO) to discuss the viability of the application at a particular point of interconnection (POI). MISO also offers a POI self-check tool to help customers pre-screen potential POIs.
2. Application Submission – In this phase, the customer submits an online interconnection request application form via MISO’s Generation Interconnection Online Portal. Relevant fields and documentation are uploaded to the portal, and MISO responds with an acknowledgment receipt within five business days of submission.
3. Application Review – MISO GI and TO teams review the application. Within 15 business days of submission, MISO notifies the customer via email of the application’s validity or any deficiencies. After receiving the notification, customers have 10 business days to correct any deficiencies. The application can only enter the GI queue if all deficiencies are cleared. After verifying customer readiness and application validity, a mandatory scoping meeting is conducted, starting 45 days before the definitive planning phases (DPPs).
4. Definitive Planning Phases (DPPs) – The DPPs comprise three phases:
- DPP 1: In this phase, MISO provides the interconnection customer with a preliminary analysis regarding the impact of the interconnection request on the transmission-system reliability. It includes model build and POI review having a timeline of 30 calendar days and preliminary system impact study (SIS) having a timeline of 90 calendar days.
- DPP 2: After incorporating the updated generation assumptions owing to potential withdrawal of interconnection requests during DPP1, in this phase, MISO provides the interconnection customer a revised and detailed analysis regarding the impact of their project on the transmission-system reliability. This phase includes model update having a timeline of 10 business days and revised SIS and interconnection facilities study (SIS has a timeline of 45 calendar days and interconnection facilities study has a timeline of 90 calendar days).
- DPP 3: After incorporating the updated generation assumptions due to potential withdrawal of interconnection requests during DPP 2, this phase provides the interconnection customer a final, detailed analysis of the interconnection project’s impact on transmission-system reliability. This phase includes model update having a timeline of 10 business days and final SIS and network upgrade facility study having timelines of 30 and 90 calendar days, respectively.
5. Generation Interconnection Agreement – Upon completion of the DPPs, the interconnection customer and native TO negotiate to create the Generator Interconnection Agreement (GIA), which MISO files with FERC.
MISO’s Benchmarking of SUGAR
MISO aims to complete the generation interconnection process within a one-year timeline, necessitating various process improvements and automation. For DPP 1 automation, MISO plans to integrate the Suite of Unified Grid Analyses with Renewables (SUGAR) software from Pearl Street Technologies into its DPP 1 studies. This integration will significantly reduce the GI process timeline. Designed to perform power flow analyses, identify network upgrades (NU), allocate costs, and validate constraint mitigation, SUGAR is a powerful tool that can save considerable time in completing the study process. MISO will begin applying SUGAR to DPP 1 of the 2022 study cycle while continuing to use existing power flow tools for DPPs 2 and 3.
To ensure SUGAR’s effectiveness and reliability, MISO conducted a benchmarking study comparing its results with those of TARA (the current tool employed by MISO). The benchmarking considered DPP 2021 Phase 1 South (Summer Discharge) study models along with other monitoring, contingency, and subsystem files. The entire Phase 1 process was completed within 10 days using SUGAR, compared with 686 days taken by TARA. Both studies suggested similar network upgrade cost estimates ($13.25B by SUGAR and $13.36B by TARA). The benchmarking focused on comparing thermal (Energy Resource Interconnection Study (ERIS) and Network Resource Interconnection Study (NRIS)) and voltage analyses results of SUGAR with those of a previous MISO study cycle. The following observations were made:
1. ERIS Thermal Results: SUGAR captured 259 of the 261 ERIS thermal constraints reported by TARA (99.23% overlap) and identified one constraint not observed in TARA results.
2. NRIS Results: All 267 NRIS constraints reported by TARA were also identified by SUGAR.
3. Voltage Analysis Results: Of the 103 ERIS voltage constraints identified by TARA, 102 were captured by SUGAR (99.03% overlap), with SUGAR reporting six additional constraints not observed in TARA results.
Minor deviations between SUGAR and TARA results fell within limits acceptable to MISO and were attributed to inherent differences between the two software in their respective power flow methodologies and screening behavior.
Conclusion
In conclusion, while MISO does not intend to completely replace existing power flow and interconnection tools with SUGAR, it plans to use SUGAR for DPP 1. The benchmarking results confirm SUGAR’s effectiveness in significantly accelerating the process while providing highly accurate results within acceptable limits. This integration marks a substantial improvement in MISO’s ability to manage the generation interconnection process efficiently and reliably, paving the way for a more streamlined and effective approach to energy management.
As MISO embraces innovation to reduce interconnection timelines and modernize the grid, tools like SUGAR represent a meaningful step forward in advancing renewable energy development at scale. For developers navigating MISO’s evolving interconnection process, understanding each phase—and how automation is reshaping them—is critical to staying ahead.
At ZEG, we help clean energy developers succeed in complex interconnection environments with expert guidance on transmission planning, queue strategy, and regulatory insights. Reach out to our team to ensure your project is positioned for success in the MISO grid.
