Studies and Reports > 2025 Biennial Report >Transmission Planning Zones

9.0 Outages & Congestion

9.1   Introduction

The Commission’s June 29, 2022 Order Accepting Report required MTO to include the information required to be filed in the 2021 Report in their 2023 Report as well as the following:

• Expected sustained HVTL or generation planned outages;
• Whether those outages are anticipated to have new or incremental congestion; and
• Whether those outages are anticipated to contribute to sustained incremental congestion.

The 2025 Report also provides updates on Grid North Partners and the MTO’s work related to congestion and specifically in response to the Commission’s March 24, 2025 Order in Docket No. E999/CI-24-316.

9.2  System Changes and Upcoming Projects Addressing Congestion Relief

Congestion is a limitation, constraint, or “bottleneck” on the transmission grid which prevents the lowest cost-generation from serving load. Congestion exists on the transmission system at nearly all times. Some level of congestion is expected and normal as the transmission grid is built for the lowest total costs to serve customer and member demands. Eliminating all congestion does not result in a lower total cost as it would require a significantly overbuilt transmission grid. Total costs consider the out-the-door impacts of both transmission and generation cost. Thus, when evaluating congestion projects, it is typical to determine if the generation savings results from reducing congestion exceed the capital cost of the transmission expansion. Congestion relief project effectiveness is typically measured in either net savings (generation savings less transmission costs) or a benefit to cost ratio (generation savings divided by transmission cost).

Figure 1 - Congestion Trends in MISO and Minnesota and the surrounding area (Local Resource Zone (LRZ) 1)

For the past five years, congestion levels across MISO and Minnesota and the surrounding area have been on the rise, as shown in Figure 1. However, recently overall congestion levels in Minnesota have decreased also as shown in Figure 1. Congestion levels are driven by several factors including:

• System outages: Similar to road construction causing traffic back-ups, transmission line or generation outages can cause increased congestion. Generally, the more outages, the more congestion. It should be noted that to construct congestion relief projects or other transmission upgrades, it often requires outages on the transmission elements which are most congested, exacerbating congestion in the short-term.
• Generation and transmission construction timelines: Generators can typically be constructed faster than the transmission facilities needed to fully accommodate the generation. This lag in transmission construction results in a temporary increase in congestion.
• Weather: As wind and solar generation constitute a larger share of the generation fleet, weather patterns, especially atypical weather patterns, can result in increased congestion levels.
• Demand levels: The transmission grid moves generation from where it is produced to where it is needed, and thus it is not only generation output but more so how it is coupled with demand levels and location.

As the transmission grid does not stop at state borders, transmission limitations in other states can drive congestion in Minnesota, and vice versa.
The MTO utilities have taken numerous actions in the short-, mid-, and long-term to alleviate congestion throughout the state.

Long-Term Actions: Complete solutions which address existing congestion and proactively accommodate future changes but typically require five to ten years to implement. Long-term MTO actions include:

• MISO Long-Range Transmission Plan (LRTP) Tranche 1 portfolio which includes three 345kV projects in Minnesota – see Section 10.2 for additional information.
• MISO Long-Range Transmission Plan (LRTP) Tranche 2.1 portfolio which includes five high-voltage projects in Minnesota – see Section 10.3 for additional information.
• Xcel Energy’s MN Energy Connection and King Connection, which are designed to utilize existing transmission access rights. The MISO interconnection queue has a significant number of new interconnection requests currently seeking to connect to a system that is already very congested. Reusing existing transmission rights through the MN Energy Connection and King Connection Projects allows Xcel Energy to interconnect additional MWs through its existing transmission rights, avoiding long delays often related to MISO queue interconnection studies.

Near-Term Actions: Incremental solutions to maximize use of existing assets such as rating adjustment technologies and other limited scope fixes which can be implemented within a few years. MTO near-term actions include:

• In 2025, the MTO via the GETs study identified 26 solutions which will be implemented by MTO utilities. Solutions include GETs, substation equipment upgrades, and transmission line upgrades – see Section 9.4 and Appendix B for additional information.
• GRE has a dynamic line rating (DLR) pilot program with Heimdall. As of June 2025, GRE has ten lines with DLR which are monitored by 50 physical sensors and 37 “virtual sensors.” GRE is planning on expanding the pilot program with seven additional sensors in late summer 2025. In addition, GRE is evaluating further expansion of its DLR program and other technologies.25
• Xcel Energy implemented a process to study reconfiguration requests from outside entities. These requests are looked at to determine effectiveness, duration, and impact to the transmission system. Reliability is the primary determinant of whether a reconfiguration request is approved.
• Xcel Energy initiated an internal study process to determine any transmission system reconfigurations on the underlying transmission system able to have a positive impact on the bulk transmission system and congestion. Xcel Energy Transmission Operations factor system reliability, curtailment, and congestion when considering/scheduling transmission outages.

Mid-Term Actions: Grid expansion designed to incrementally decrease congestion and bridge to long-term solutions. Mid-term solutions typically require two to five years to implement depending on complexity. MTO near-term actions include:

• In 2023, Grid North Partners announced plans to construct 19 transmission solutions, 18 of which will be in Minnesota, to reduce transmission congestion in the near-term for the broader benefit of customers throughout the Upper Midwest – see Section 9.3 for additional information.
• NSP System Upgrades: Xcel Energy conducted an internal analysis to determine projects designed to remove system limiters on congested lines in southwest Minnesota. These projects typically addressed substation equipment and sag limits. See Section 9.6 for additional information.
• Xcel Energy initiated an out-of-cycle request for MISO in 2023 to complete the second 345 kV circuit from Brookings Co-Lyon Co and Helena-Hampton for the existing CAPX Brookings-TC facility. The Brookings County to Lyon County circuit and the Helena to Hampton circuit are currently in-service.

In addition to implementing physical solutions, the MTO is working with MISO to help ensure study processes and assumptions more proactively address congestion. As an example, the MTO worked with MISO and other stakeholders to change how ERIS impacts are identified in the MISO DPP process. The previous distribution factor (DF) was 20% and as proposed by the MTO, the current DF is 10% which helps ensure that more generation is not interconnected without necessary transmission facilities being built to deliver the energy to the system.

These examples represent MTO members’ commitment to actively addressing congestion issues impacting the grid statewide. Going forward, MTO will continue collaborating with other stakeholders to address congestion issues.

9.3  Grid North Partners 2023 Near-Term Congestion Study

In late 2023, Grid North Partners announced plans to construct 19 transmission solutions, 18 of which will be in Minnesota, to reduce transmission congestion in the near-term for the broader benefit of customers throughout the Upper Midwest.²⁶ These solutions are expected to provide congestion relief savings in excess of cost and furthermore will help reduce congestion caused during the construction of MISO’s Long Range Transmission Plan.

Grid North Partners, an evolution of CapX2020, is a voluntary partnership of ten Minnesota and surrounding area transmission-owning utilities. The Grid North Partnership members include Central Municipal Power Agency/Services, Dairyland Power Cooperative, Great River Energy, Minnesota Power, Missouri River Energy Services, Otter Tail Power Company, Rochester Public Utilities, Southern Minnesota Municipal Power Agency, WPPI Energy, and Xcel Energy. Additional information on Grid North Partners can be found at https://gridnorthpartners.com/.

Grid North Partners utilities collectively and individually have advocated for and continue to participate in MISO’s long-range transmission planning efforts. While those long-range plans are the true solution to address congestion in Minnesota, in parallel Grid North Partners has been collectively analyzing congestion to identify near-term congestion solutions.

In 2023, Grid North Partners conducted a study to identify solutions to incrementally address congestion in the near-term (i.e. in-service within three years). The ten Grid North Partners utilities collectively analyzed both historical congestion from the past two years and forward congestion projections for Minnesota and the surrounding region. For every congested element, the limiting element (e.g., conductor, substation equipment, sag, structure, etc.) and time and cost to upgrade were identified. Ultimately, 19 solutions were identified, shown in Table 1, which will be constructed by the individual Grid North Partner member. While one of the 19 solutions is larger scale - the Brookings second circuit (Docket No. ET-2/TL-08-1474)– the others are mostly small- scale upgrades of existing equipment with no new required right-of-way.

As shown in Table 1, the status of the 19 projects as of September 2025 is:

• Fourteen (count) projects - Completed and in-service
• One - Under-construction and expected to be in service by year-end
• Two – Planned or under-development. Construction pending material delivery and/or outage schedules.
• Two – On hold/temporarily cancelled. Cost for materials necessary to complete have increased where congestion savings are no longer expected to exceed solution costs. Congestion trends and material costs will continue to be monitored to determine if/when projects will move forward.

Table 1: Grid North Partner 2023 Near Term Congestion Project Status

When Grid North Partners announced the near-term projects in 2023, plans were also announced to conduct a second iteration of the study after MISO’s Long-Range Transmission Plan Tranche
2.1 portfolio²⁸ was solidified. Due to the similar mandated outcomes of Minnesota 2024 statute changes on GETs,²⁹ the second iteration of the Grid North Partners near-term congestion study was merged into the GETs Study described in Section 9.4. As described in Section 9.4 the GETs Study identified both GETs as defined by Minnesota law as well as near-term solutions like those identified in the 2023 Grid North Partners study. The full GETs Report is available in Appendix

Grid Enhancing Technologies (GETs) Study Summary

Appendix B provides the full Grid Enhancing Technologies (GETs or GETS Report) as required by Minnesota legislation to be filed in conjunction with the 2025 BTPR. The GETs Report addresses 30 solutions that are being developed to address congestion in the near term. This report details historic and future congestion information for the Grid North Partner's (GNP),³⁰ ITCM, and MPC footprint within Minnesota. The legislation states that any electric utility owning more than 750 miles of transmission in Minnesota must review historical congestion facilities, determine GETs solutions for each congestion point, and develop implementation plans for those GETs solutions that meet Commission defined payback period. GETs are hardware or software that reduces congestion or enhances the flexibility of the transmission system by increasing the capacity of a high-voltage transmission line or rerouting electricity from overloaded to uncongested lines, while maintaining industry safety standards. Grid enhancing technologies include but are not limited to dynamic line rating, advanced power flow controllers, and topology optimization.

Potential Congestion Based on Future Facility Additions

Notwithstanding the MTO’s efforts described in Section 9.2, MTO believes that there is the potential for continued congestion issues over the next decade. Efforts to bring new transmission resources are underway; however, the planning, approval, and construction processes take time. Additionally, as described in Section 9.2, congestion relief projects often require outages of transmission lines temporarily exacerbating congestion issues.

In 2024, MISO conducted the Near-Term Congestion Study to identify the congestion impacts caused by the construction of the LRTP Tranche 1 portfolio lines. While the LRTP Tranche 1 portfolio is expected to reduce congestion and provide $13 to $18 billion in congestion and fuel savings over the first twenty years of service,³¹ construction is expected to take five years. MISO’s study shows that during those five years of construction historical congestion issues will increase and shift some congestion to other facilities. MISO’s report shows that construction sequencing can help decrease construction related congestion. MISO’s report also solicits for potential Grid Enhancing Technology (GETs) solutions, like those being implemented by MTO members described in Section 9.2 and 9.3, to decrease construction related congestion. A full copy of MISO’s Near-Term Congestion Study can be found at the following URL: https://cdn.misoenergy.org/MTEP24%20Near-Term%20Congestion%20Study%20Report657728.pdf

In addition, in December 2024, the MISO Board of Directors approved the Tranche 2.1 portfolio which includes 24 high-voltage transmission projects across the Midwest – see Chapter 10.3 for additional information. A key feature of the portfolio is the creation of a new 765 kV transmission backbone, including across southern MN, to transfer large amounts of electricity efficiently across the region to maintain reliability and reduce congestion and curtailment. The projects are scheduled to be in service between 2032 and 2034. The constructing MTO members will coordinate with MISO and the various Tranche 2.1 owners to sequence construction to help minimize facility outages and congestion. In addition, the MTO continues to look for creative solutions to minimize system congestion while waiting for additional transmission resources to come online.

Nobles County Congestion Analysis

Xcel Energy Transmission Planning performed a screening system impact study (SIS) to evaluate voltage stability benefits of a future battery energy storage system (BESS) to the local area around the Nobles 115/345 kV station.³² The most recent operations guide for the Southwest Minnesota wind region lists outages requiring local wind generation to be limited to maintain voltage stability. The guide describes operating conditions causing voltage instability if select groups of wind generators exceed a pre-determined MVA threshold. This screening SIS determined that a 300 MW BESS with grid forming inverter at the Nobles station will provide dynamic voltage stability benefits to the system in dispatches with high wind generation.³³ These benefits are observed when utilizing a grid-forming inverter. This Nobles Grid-Forming Battery Screening System Impact Study is provided in Appendix C.

Xcel Energy also completed an screening economic analysis using historical Locational Marginal Prices (LMP) to determine if there would be any economic benefit to adding a 300 MW Energy Storage Unit at the Nobles County substation. Based on this preliminary analysis it shows that a 300 MW BESS would have a positive impact on curtailments in the area if installed. This Nobles Battery Economic Screening Study is provided as Appendix D. Final analysis will need to be performed once final determinations are made regarding the specific technical details of the Nobles BESS.

25 Additional information on GRE’s DLR pilot program and the first-year results can be found at: https://www.heimdallpower.com/whitepaper-one-year-gre?utm_campaign=150436053-one-year-gre

26 Congestion-projects-press-release-Grid-North-Partners-2023.pdf (gridnorthpartners.com).

27 AAR: Ambient Adjusted Rating

28 See Section 10 for additional information on the Long Range Transmission Plan

29 2024 Minn. Laws, Ch. 127, Article 42, Section 52.

30 Grid North Partners, an evolution of CapX2020, is a voluntary partnership of ten Minnesota and surrounding area transmission-owning utilities. The Grid North Partners members include Central Municipal Power Agency/Services, Dairyland Power Cooperative, Great River Energy, Minnesota Power, Missouri River Energy Services, Otter Tail Power Company, Rochester Public Utilities, Southern Minnesota Municipal Power Agency, WPPI Energy, and Xcel Energy.

31 MTEP21 Addendum-LRTP Tranche 1 Report with Executive Summary625790.pdf – page 50

32 A screening-level study was conducted to evaluate the potential impact of a 300 MW BESS at Nobles. The results are preliminary and rely on assumptions about the grid-forming inverter, which will be refined once Xcel Energy selects the final technology.

33 Xcel Energy submitted an application into the MISO ERAS process for a BESS at its Nobles Substation and is continuing to develop the details of the project and expects to request approval of the Nobles BESS and other ERAS projects in early 2026.