Minnesota Electric Transmission Planning

Project Description: Add a second 230/115 kV transformer at the Hilltop Substation and upgrade an existing line from 115 kV to 230 kV between the Arrowhead and Hilltop substations.

Need Driver: Reliability and load growth in the Duluth area. Retirement of local generators on the 115 kV system. Maintaining sufficient 230/115 kV transformer capacity for load serving in the Duluth area during a maintenance outage of one of the existing Arrowhead 230/115 kV transformers or following certain single contingency events.

Alternatives:

Transmission Alternatives

Build a new 230/115 kV substation in the Duluth area.

Non-Wires Alternatives

Install new dispatchable generation in the Duluth area. Non-wire alternatives must be dispatchable to respond when called upon and of sufficient duration to prevent or mitigate overloading. Minnesota Power will continue to consider non-wire alternatives alongside the Duluth 230 kV Project as the need and timing for the project develop.

Analysis: In 1993, Minnesota Power constructed a new 230 kV substation (the Hilltop Substation) in Duluth. This project involved the rebuilding of existing 115 kV lines for 230 kV operation in order to provide a single 230 kV source to the Hilltop Substation and upgrades of several unshielded 115 kV lines to improve reliability. As part of the application for the Hilltop Project MP laid out long range plans which identified the future need for a second 230 kV source to the Hilltop Substation once Duluth load dictated its need. The Commission recognized this future need and approved rebuilding of portions of the unshielded 115 kV lines as part of the Hilltop Project for future 230 kV operation.

Because Minnesota Power anticipated this future need, a relatively minimal amount of transmission line and substation construction will be required to implement the Duluth 230 kV Project when it becomes needed. Due to the configuration of the existing Duluth area transmission system, the Duluth 230 kV Project is expected to be the most cost effective and least environmentally impactful solution to this pending inadequacy. Other transmission alternatives would require longer 230 kV line construction and the establishment of a new substation site, increasing social, environmental and economic impacts associated with construction of such a project. Operational changes that limit through-flow on the Duluth-area 115 kV system have proven helpful in delaying the need for this project, as discussed below. The Duluth Loop Reliability Project (2019-NE-N12) will include incremental improvements at the Arrowhead and Hilltop Substations, such as a larger 230/115 kV transformer and a 230 kV breaker at Hilltop and sectionalization of the Hilltop 230 kV line at Arrowhead. These incremental improvements are expected to further delay the need for the more significant expansion of Duluth area 230/115 kV transformer capacity that would be achieved with the Duluth 230 kV Project.

Schedule: Slower than anticipated load growth, external system improvements such as the Arrowhead-Stone Lake-Gardner Park 345 kV Line, and operational flexibility provided by the phase shifting transformer at the Stinson Avenue Substation in Superior, Wisconsin, have delayed the need for the Duluth 230 kV Project for many years. Based on recent studies indicating a need for improved reliability and capacity of Duluth-area 230/115 kV transformers in the first half of the 2020s, Minnesota Power has included incremental improvements at the Arrowhead and Hilltop Substations as part of the Duluth Loop Reliability Project (2019-NE-N12). The underlying system drivers behind the timing of the incremental improvements included with the Duluth Loop Reliability Project are related to the impact of a number of transitional changes in the nearby North Shore Loop transmission system and changing regional transfers in and through the Minnesota Power system. These incremental improvements will shift the primary need drivers for the Duluth 230 kV Project back to local Duluth-area load growth or retirement of the dispatchable generators at the Hibbard Renewable Energy Center, likely delaying the need for the Duluth 230 kV Project to the late 2020s or even into the 2030s.

General Impacts: The Duluth 230 kV Project will make optimal use of an existing transmission line that was designed for future conversion for 230 kV operation and existing substations designed with space in or adjacent to the existing footprint to accommodate additional 230 kV connections. Since the Duluth 230 kV Project is using existing substations, transmission line corridors and rights-of-way, it is anticipated that no new landowners would be impacted by the project. The Duluth 230 kV Project is needed to maintain adequate power delivery capability from the transmission system to the Duluth area in light of local generator retirements, regional transfers, load growth, and economic development. Therefore, the project contributes to the realization of significant environmental, social, and economic benefits associated with these contributing factors. Minnesota Power’s approach to this issue is intended to ensure that the most appropriate solution (in terms of cost and human and environmental impacts) is implemented at the most appropriate time to meet the reliability and capacity needs of Minnesota Power’s customers.

HVDC Modernization Project

Formerly Square Butte – Arrowhead HVDC Valve Hall Replacement

MPUC Tracking Number: 2013-NE-N16

MPUC Docket Number: E015/CN-22-607, E015/TL-22-611

Utility: Minnesota Power (MP)

Project Description: Replace the existing Center (Square Butte) and Arrowhead high voltage direct current (HVDC) converter stations and associated assets with modern equipment. To modernize the terminals of the existing Square Butte HVDC Line and implement the latest VSC HVDC technology, new buildings and electrical infrastructure need to be constructed on a new site near the existing HVDC terminals. In Minnesota, to connect the new HVDC terminal to the existing AC system, the Project will require the construction of a new St. Louis County 345 kV/230 kV substation located less than one mile west of the current Arrowhead Substation. The new HVDC terminal will be connected to the St. Louis County Substation by a short 345 kV transmission line, and the new St. Louis County Substation will be connected to the existing Arrowhead Substation by a double-circuit 230 kV transmission line less than one mile in length. Additionally, a short portion of the existing ±250 kV HVDC Line in Minnesota will need to be reconfigured to terminate at the new HVDC terminal. Similar modifications will take place near the existing Center HVDC terminal in North Dakota.

Need Driver: The HVDC Modernization Project is needed to modernize aging HVDC assets, continue to position the transmission grid for clean energy transition, and improve the reliability of the transmission system. The existing HVDC terminal has operated for 47 years—17 years beyond its 30-year design life. In recent years Minnesota Power has experienced HVDC terminal outages due to failures in the control system, power electronics, transformers, and other components. Based on experience with other electric system components, the failure rate is expected to increase, which is of particular concern for the existing HVDC system because of limited parts availability. The orderly replacement of the HVDC terminal equipment is prudent to ensure continuous efficient delivery and expansion of Minnesota Power’s renewable, carbon-free energy resources into the future.

In addition to the replacement of the existing HVDC terminals, the new voltage source converter (VSC) HVDC technology implemented for the Project will be designed to provide key reliability attributes including voltage regulation, frequency response, blackstart capability, and bidirectional power transfer capability. These modernizations to the HVDC technology will enable Minnesota Power and the region to continue to support its clean energy transition.

Alternatives:

Transmission Alternatives

Alternatives to the HVDC Modernization Project discussed in the Certificate of Need application include not replacing the HVDC converter stations (“Do Nothing” – risk of extended outage due to equipment failure), retiring the HVDC system and replacing it with new AC transmission improvements (“AC Alternative”), and replacing the HVDC converters with older technology similar to the original stations (“Technology Alternative”).

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition at the Center and Arrowhead HVDC converter stations.

Analysis: The HVDC Modernization Project will modernize aging assets that are critical to the reliable delivery of renewable energy to Minnesota Power’s customers, improve the reliability of the transmission system and thoughtfully position for continued clean energy system transformation. Under the “Do Nothing” alternative, failure rates of the existing HVDC Converter Station equipment are anticipated to increase, resulting in outages that impact the reliable and efficient delivery of Minnesota Power’s North Dakota wind energy and result in direct cost impacts to Minnesota Power’s customers and reliability impacts to the regional transmission system. As these outages increase in frequency and duration, the cost and reliability impacts will continue to grow. With no viable plan to modernize the existing HVDC converters, Minnesota Power would immediately need to determine if it were prudent to invest in relatively short-term fixes to keep the HVDC Line operating on a limited basis or to move on from the HVDC Line entirely and begin to develop alternative AC transmission solutions.

Under the “AC Alternative” the alternative AC transmission solutions required to facilitate continued delivery of Minnesota Power’s zero fuel cost North Dakota wind energy, mitigate system impacts caused by the retirement of the HVDC Line, and replace the grid support provided by the VSC HVDC converters would come at a substantially higher cost and with greater human and environmental impacts than the HVDC Modernization Project. Given that the AC Alternative would need to include multiple regional-scale 345 kV transmission lines, there would likely be prolonged exposure to outages of the HVDC Line during the 10 or more years it would take to develop these projects. At some point during that time, it may become impossible to continue operating the HVDC Line at its full capacity, leading to extended outages and associated impacts to Minnesota Power’s customers and regional reliability.

Were Minnesota Power to choose to invest in relatively short-term fixes to keep the HVDC Line operating on a limited basis, these fixes would result in significant risk of stranded investment as the regional transmission system develops. The “Technology Alternative” including targeted replacements of the existing control system, converter transformers, and thyristor valves could serve to keep the existing LCC HVDC system running for several more decades at its existing capacity. These replacements would not bring the additional grid-supporting attributes associated with VSC technology, and therefore additional investments in STATCOMs, synchronous condensers, or other solutions may become necessary as the clean energy transition continues to challenge the historical operating conditions of the grid. As MISO continues to advance proactive long-range transmission planning solutions to position the grid for the future of clean energy, VSC HVDC solutions will inevitably begin to play a major role in the regional grid. At that point, Minnesota Power’s short-term investments in keeping its existing LCC HVDC system may have to be replaced before the end of their useful asset life by a VSC HVDC upgrade similar to the Project in order to continue reliable operation of the Square Butte HVDC corridor and provide the best value for Minnesota Power’s customers and the region.

The HVDC Modernization Project is the only prudent solution to limit cost impacts to Minnesota Power’s customers in the near-term from increased exposure to HVDC outages, avoid substantial additional long-term cost for alternative projects to address reliability issues created by retirement of the HVDC Line, and align with opportunities to efficiently provide long-term bulk power transfer and grid support solutions for Minnesota Power and the region.

Schedule: Minnesota Power filed a combined Certificate of Need and Route Permit Application for the HVDC Modernization Project on June 1, 2023 [Docket Nos. E015/CN-22-607 and E015/TL-22-611], and the Commission granted the Certificate of Need and Route Permit on October 25, 2024. Site development for the converter stations in both Minnesota and North Dakota began in mid-2025, and the Project has a targeted in-service date between April 2029 and April 2030.

General Impacts: The modernization of Minnesota Power’s HVDC converter stations is a prudent and necessary activity to ensure the ongoing operation of this critical piece of transmission infrastructure for Minnesota Power’s customers, including the reliable delivery of Minnesota Power’s substantial North Dakota wind generation assets.
The HVDC Modernization Project is also a critical component of Minnesota Power’s efforts to leverage existing infrastructure to efficiently maintain the current load, gain additional access to renewable resources for customers, and keep momentum for reaching the state’s goal of 100 percent carbon-free energy by 2040. The Project innovatively proposes flexible design options to allow for future expansion and additional renewable energy transfer capability, leveraging the unique attributes of VSC HVDC technology—the most efficient way to transfer power over long distances. In addition to the replacement of the existing HVDC terminals, the new Voltage Source Converter (VSC) HVDC technology implemented for the Project will be designed to provide voltage regulation, frequency response, blackstart capability, and bidirectional power transfer capability, all of which will enable Minnesota Power and the region to continue to support its clean energy transition reliably. All of this will be implemented in a relatively small geographic area near the existing Arrowhead 230 kV Substation, limiting human and environmental impacts by leveraging the existing site and contiguous lands to the greatest extent possible.

HVDC 900 MW Transmission Line Upgrades

Formerly Square Butte – Arrowhead HVDC Upgrade

MPUC Tracking Number: 2013-NE-N17

Utility: Minnesota Power (MP)

Project Description: Upgrade the capacity of the existing Square Butte – Arrowhead HVDC transmission line from 550 MW to 900 MW, generally by replacing existing structures with taller structures and reconductoring a short segment of line.

Need Driver: Transmission Service Requests (TSRs) filed with MISO for additional capacity to facilitate increased renewable energy transfers on the HVDC Line following the completion of the HVDC Modernization Project (Tracking No. 2013-NE-N16).

Alternatives:

Transmission Alternatives

Develop AC network upgrades necessary to facilitate the same amount of additional renewable energy interconnection and regional transfer capability.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot provide additional capacity for long-distance renewable energy transfers on the existing HVDC Line.

Analysis: Minnesota Power has assessed the capacity limitations associated with the existing HVDC Line and found that the total capacity of the HVDC Line may be reasonably increased from 550 MW to a maximum of 900 MW following completion of the HVDC Modernization Project (Tracking No. 2013-NE-N16). To achieve the higher capacity, upgrades would be needed at various locations along the length of the 465-mile HVDC transmission line. These upgrades are expected to include replacing existing structures with taller structures to increase conductor-to- ground clearance at a higher operating temperature, as well as replacement of a short segment of smaller conductor in North Dakota. Leveraging the opportunity to incrementally increase the capacity of the HVDC Line following completion of the HVDC Modernization Project provides an efficient solution for facilitating the interconnection and long-distance delivery of additional high-capacity renewable energy resources to Minnesota Power’s customers.

Schedule: At the request of Minnesota Power, MISO updated Transmission Service Request (“TSR”) System Impact Studies on varying levels of increased HVDC capacity in 2022-2023 and provided Facilities Studies documenting the costs assigned to the TSRs. Two Facilities Construction Agreements (“FCA”) for the upgrades necessary to provide the requested incremental transfer capability were executed on February 28, 2024, and subsequently filed with and accepted by FERC. Minnesota Power plans to construct the HVDC transmission line upgrades. in phases between 2026 and 2029 to limit HVDC Line outage impacts.

General Impacts: The additional capacity facilitated by the HVDC 900MW Transmission Line Upgrades Project will facilitate increased wind development in North Dakota, more efficient market operation, and system reliability enhancements for both North Dakota and Minnesota. Since the project is anticipated to take place within the existing transmission line right-of-way, it is anticipated that no new landowners would be impacted by the project.

25 Line Rebuild

MPUC Tracking Number: 2019-NE-N4

Utility: Minnesota Power (MP)

Project Description: Increase rating of Maturi – Virginia 115 kV Line (25 Line). The project also includes rebuild, reconductor, and switch replacements along the transmission line and in the vicinity of the existing Minntac Tap.

Need Driver: Post-contingent overloads under higher transfer scenarios and multiple-circuit contingency events, as well as age and condition of existing 25 Line structures and hardware.

Alternatives:

Transmission Alternatives

Reconductor existing line, build new parallel line.

Non-Wires Alternatives

Install new dispatchable energy resource in the area. Non-wire alternatives must be dispatchable to respond when called upon, of sufficient duration, and at an effective location to prevent or mitigate overloading. However, non-wire alternatives can only address the capacity needs and would not displace the need for asset renewal components of the project.

Analysis: This issue has been identified in MTEP and in several Minnesota Power studies. The upgrade project provides the needed capacity increase as identified in the studies while also efficiently addressing asset renewal needs along the length of the line.

Schedule: The project has been delayed to align with other asset renewal and substation modernization projects in the area. Minnesota Power is currently targeting a 2029 in-service date for the project.

General Impacts: The 25 Line Upgrade Project will provide necessary system improvements and asset renewal on Minnesota Power’s 115 kV system without requiring the establishment of additional transmission line corridors. During construction, MP and/or their contractors will be working in the area and will contribute positively to the local economy. No significant traffic impacts are anticipated. The right-of-way will be restored following construction.

Badoura 230/115 kV Transformer Replacement

MPUC Tracking Number: 2019-NE-N8

Utility: Minnesota Power (MP)
Project Description: Replace existing 230/115 kV transformer at Badoura substation and add 230 kV line breakers.
Need Driver: Age and condition of Badoura transformer. Transformer is also non-standard and there is no direct system spare. Post-contingent overloads following multiple-circuit contingency events in the surrounding area.

Alternatives:

Transmission Alternatives

Increase facility ratings to mitigate post-contingent overloads.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition and non-standard equipment at Badoura.

Analysis: The Badoura 230/115 kV transformer is non-standard for Minnesota Power’s system, as it consists of an external 115 kV voltage regulating transformer rather than an internal load tap changer. The transformer is also nearly 60 years old. The project will replace it with a new standard-sized 230/115 kV transformer, for which Minnesota Power maintains a system spare. Studies have indicated that the voltage regulation from the transformer is not necessary and therefore the new transformer will be procured without load tap changers. Additionally, there are no breakers at the Badoura 230 kV Substation, which creates difficulties with relaying and contingencies that cause large parts of the area between Riverton and Park Rapids to lose critical transmission connections. Installing breakers will mitigate issues associated with these contingencies and provide for better protection of the transmission lines and transformer. Post- contingent overloads on the Badoura 230/115 kV Transformer were first identified in the MTEP18 2023 winter peak case

Schedule: The project is currently targeted for an in-service date of 2027.

General Impacts: The Badoura Transformer Replacement Project will ensure a continuous and reliable power supply to a large area of the Minnesota Power transmission system between Riverton and Park Rapids by replacing aging, non-standard equipment before it fails and by improving system protection through the addition of breakers. The Project will make use of space available inside the existing Badoura 230/115 kV Substation, as all modifications associated with the project will take place within the existing substation fence-line.

Duluth Loop Reliability Project

MPUC Tracking Number: 2019-NE-N12

Utility: Minnesota Power (MP)

Project Description: Construct approximately 14 miles of new 115 kV transmission between the existing Hilltop, Haines Road, and Ridgeview substations. Some existing 115 kV transmission lines in the area will be reconfigured and upgraded. At the existing Ridgeview Substation, the substation yard will be expanded to accommodate a new 115 kV ring bus with 4 new 115 kV circuit breakers and a new transmission line entrance. At the existing Haines Road Substation, a 115 kV circuit breaker will be added to an existing transmission line entrance. At the existing Hilltop Substation, the substation yard will be expanded to accommodate a new 115 kV line entrance, the existing 230/115 kV transformer will be replaced with a larger-capacity transformer, a new 230 kV circuit breaker will be added, and four existing 115 kV circuit breakers will be replaced. At the existing Arrowhead Substation, a new 230 kV transmission line entrance will be constructed. The existing Hilltop 230 kV tap will be disconnected from the Arrowhead – Iron Range 230 kV Line (98 Line) and extended approximately 0.7 miles to the new line entrance at the Arrowhead Substation to become the Arrowhead – Hilltop 230 kV Line (108 Line). The existing Hilltop 230 kV tap transmission line will be upgraded to a higher operating temperature and existing polymer insulators will be replaced. Additional substation and transmission line components will also be replaced as part of the project due to age and condition.

Need Driver: Following conversion, idling, or retirement of coal-fired baseload generators in the North Shore Loop, there is a risk of voltage collapse during maintenance outages of 115 kV lines between Arrowhead, Haines Road, Swan Lake Road, Ridgeview, and Colbyville Substations. Loss of a second transmission line during one of these maintenance outages would leave this part of Duluth on a single 140-mile transmission line originating in the Hoyt Lakes Area, with the transmission system no longer able to support the load over that distance without the baseload generators. The Duluth Loop Reliability Project will restore redundancy and load-serving capability to this area, mitigating the risk of voltage collapse. Duluth area 230/115 kV transformer loading also increases significantly without the local baseload generators online and connected to the 115 kV system. This causes a risk of severe overloads on the existing 230 kV line and the Hilltop 230/115 kV transformer during a maintenance outage of either of the Arrowhead 230/115 kV transformers. Upgrading the capacity of the existing Hilltop 230 kV tap line and Hilltop

230/115 kV transformer will mitigate these severe overloads. Extending the Hilltop 230 kV tap line into the new line entrance at the Arrowhead Substation will greatly improve the reliability of the 230 kV source at the Hilltop Substation by reducing over 64 miles of outage exposure to the sole source to the Hilltop Substation and eliminating a breaker failure event which could simultaneously disconnect two 230/115 kV transformers in the Duluth area. This reconfiguration will also allow significant relay protection improvements to the existing Iron Range – Arrowhead 230 kV Line (98 Line) and the newly established Arrowhead – Hilltop 230 kV Line (108 Line).

Alternatives:

Transmission Alternatives

New 115 kV or 230 kV line parallel to Arrowhead – Colbyville 115 kV path(s).

Non-Wires Alternatives

New dispatchable transmission- or distribution-connected generation in the Duluth 115 kV Loop; dynamic reactive support and transmission line capacity upgrades in the Duluth 115 kV Loop and the North Shore Loop. Non-wire alternatives must be dispatchable to respond when called upon, of sufficient duration, and at an effective location to prevent or mitigate voltage concerns.

Analysis: The Duluth Loop is a network of 115 kV transmission lines and substations which form two parallel connections between the main Duluth-area transmission source of power and system support (the Arrowhead 230/115 kV Substation) and the North Shore Loop (beginning at the Colbyville Substation on the far eastern end of Duluth). Many of the customers in the Duluth area are served from substations connected to the Duluth Loop.

The Duluth Loop Reliability Project meets three critical needs for the Duluth area and the North Shore Loop, as discussed below.

First, the project addresses severe voltage stability concerns by providing another transmission source to the Duluth Loop and North Shore Loop. For most transmission outages in the Duluth Loop, the loss of a second Duluth Loop transmission line during the outage would leave all or part of the Duluth Loop and the North Shore Loop on a single 140-mile transmission line originating in the Hoyt Lakes area. Without the support previously provided by the local baseload generators on the North Shore Loop, the transmission system is no longer able to support the large amount of Duluth Loop load over such a long distance and the expected result would be a post-contingent voltage collapse in the Duluth Loop and extending up the North Shore toward Two Harbors. To manage the risk of voltage collapse in real-time operations, the Regional Transmission Operator (MISO) directs Minnesota Power to open the North Shore transmission connection at Colbyville, separating Duluth from the North Shore Loop during planned outages in the Duluth Loop. This causes Duluth Loop load to be served through a single transmission path from the Arrowhead substation and load along the North Shore to be served through a single transmission path from the Taconite Harbor substation. This operational solution serves mostly to contain the problem rather than resolve it, as the loss of a second Duluth Loop or North Shore Loop transmission line would still result in loss of power for many residential, commercial, and industrial customers. Constructing a new 115 kV transmission line between the Hilltop and Ridgeview substations will replace the redundancy once provided by the local baseload generators such that there is sufficient

load-serving capability to support all loads in the area and sufficient flexibility to operate and maintain the system reliably without putting customers at risk.

Second, the project provides load serving capacity to the Duluth Loop and North Shore Loop. For most transmission outages impacting the Taconite Harbor Substation, a majority of load along the North Shore is served through the Duluth Loop. For this scenario, an outage along either connection between the Arrowhead and Colbyville substations could cause significant overloads along the remaining connection. Alternately, if the North Shore Loop is intact and an outage occurs on both transmission connections between the Arrowhead and Colbyville substations, significant overloads could occur on transmission lines between the Taconite Harbor, North Shore, and Big Rock substations. Constructing a new 115 kV transmission line between the Hilltop and Ridgeview substations will provide sufficient Duluth Loop and North Shore Loop transmission capacity to prevent transmission line overloads.

Third, the project improves the reliability of Duluth area transmission sources. Two 230/115 kV transformers at Arrowhead and one at Hilltop deliver power to 115 kV transmission lines in the Duluth area from the regional 230 kV transmission network. The reliance of the Duluth Loop and the North Shore Loop on these transformers has greatly increased with the idling of North Shore Loop coal generators. The Hilltop Substation is served by a single, 72-mile, 230 kV three terminal transmission line which also connects to the Arrowhead and Iron Range substations. Breaking the three terminal transmission line and extending this 230 kV transmission line approximately 0.7 miles and adding a breaker at the Arrowhead Substation will create two distinct transmission lines and reduce line mile exposure to Hilltop from 72 miles to 8 miles, greatly improving the reliability of the sole 230 kV source to the Hilltop. The additional breaker for this line connection at Arrowhead will eliminate a single point of failure which disconnects a 230/115 kV transformer at both Arrowhead and Hilltop, likely causing overloads on the remaining Arrowhead 230/115 kV transformer. Improving the reliability of Duluth Area 230/115 kV transformers will benefit customers in the Duluth Loop and along the North Shore as reliance on these transmission sources increases with the local baseload generators offline.

Schedule: Minnesota Power submitted a combined Certificate of Need and Route Permit application to the Commission in October 2021 [Docket Nos. E015/CN-21-140 and E015/TL-21- 141], which was approved in February 2023. Following permitting and engineering activities, project construction began in 2024 and will continue taking place in 2025-26.

General Impacts: The Duluth Loop Reliability Project is a critical component to maintaining a reliable system in the face of significant changes in the North Shore Loop. Replacing redundancy, voltage support, and power delivery capability previously provided by local baseload coal units in the area and improving the reliability of an increasingly critical transmission connection for delivery of power into the North Shore Loop enables the realization of significant economic and environmental benefits from transitioning away from these units. The proposed project will require approximately 0.7 miles of new 230 kV transmission and 14 miles of new 115 kV transmission, some of which will be double circuited with an existing transmission line. New transmission line construction will be primarily along existing transmission line corridors and utilize existing rights- of-way to the greatest possible extent to help navigate areas of Duluth with varying land use and space constraints. Minnesota Power has taken into consideration all relevant human, environmental, and commercial interests in the area and has actively engaged impacted stakeholders in routing and siting of the project.

National Breaker Replacements

MPUC Tracking Number: 2019-NE-N13

Utility: Minnesota Power (MP)

Project Description: Replace end-of-life circuit breakers and associated equipment at National Taconite 115 kV Substation.

Need Driver: Age and condition.

Alternatives:

Transmission Alternatives

There is no more economical or less impactful solution than replacing the existing circuit breakers.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition at the National Taconite Substation.

Analysis: Five 115 kV oil circuit breakers from 1966 will be replaced as part of this project.

Schedule: The project has been constructed in stages since 2021 and is presently planned to complete construction in 2026. While most of the project has already been completed, significant outage constraints at the National Taconite Substation have delayed the final completion of this project to align with a planned outage in 2026.

General Impacts: The National Breaker Replacements Project will replace end-of-life substation equipment, supporting continued transmission system reliability in the area. The project will take place entirely within the existing National Taconite Substation, which is located on mine property, making optimal use of the existing site infrastructure to minimize human and environmental impacts.

Hibbing Substation Modernization

MPUC Tracking Number: 2021-NE-N3

Utility: Minnesota Power (MP)

Project Description: The Hibbing Substation is located west of Hibbing, Minnesota, The Hibbing Substation Modernization project involves replacing aging equipment, structures, and civil works at the substation as part of Minnesota Power’s asset renewal program

Need Driver: The Hibbing Substation serves the City of Hibbing as well as other Minnesota Power customers in the area surrounding Hibbing. The primary need driver for the Hibbing Substation Modernization project is the age and condition of existing transformers, circuit breakers, disconnect switches, and site infrastructure. Much of the original equipment in this substation is nearing or beyond the end of its useful life, including many of the structures and foundations. Although load will be shifted off the Hibbing Substation onto the expanded Maturi Substation (Project 2023-NE-N4), the Hibbing Substation is still critical for bulk electric transmission system reliability and local load-serving needs in the Hibbing area.

Alternatives:

Transmission Alternatives

Develop area transmission and distribution system to address bulk electric system transmission needs and shift load off the Hibbing Substation to alternative sources.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition at the Hibbing Substation.

Analysis: Across Minnesota Power’s system there are many transmission-to-distribution substations that require age-related upgrades. Much of the original equipment in these substations is nearing or beyond the end of its useful life. Minnesota Power’s Substation Modernization (Asset Renewal) Program involves coordinated replacement of end-of-life assets and holistic modernization improvements designed to extend the lives of these substations for the next several decades. The Program takes a holistic, site-by-site approach to facilitating the coordinated and efficient modernization of many aging substations throughout Minnesota Power’s system. In developing the scope for the Hibbing Substation Modernization Project, Minnesota Power is considering the near-term and long-term needs of the area transmission and distribution system as well as the age and condition of existing site infrastructure and modern design standards for safety, accessibility, and maintainability. The resulting project will involve a nearly complete overhaul of the site, which is expected to ensure the site remains viable and continues to reliably serve the City of Hibbing and Minnesota Power’s other customers for many decades to come.

Schedule: The project is currently anticipated to take place in stages from 2027-28 to manage outage and constructability constraints.

General Impacts: The Hibbing Substation Modernization Project will ensure a continuous and reliable power supply to the Hibbing area by replacing aging equipment before it fails. While some minor fence expansion on Minnesota Power-owned property is necessary, the majority of impacts from the project will be contained within the existing Hibbing Substation yard.

Verndale Substation Modernization

MPUC Tracking Number: 2021-NE-N4

Utility: Minnesota Power (MP)

Project Description: The Verndale Substation Modernization Project involves replacing aging electrical equipment, structures, and civil works at the existing Verndale 115/34 kV Substation as part of Minnesota Power’s asset renewal program. Multiple substation asset renewal needs will be combined with necessary distribution transformer upgrades to make up the core of this project. This work at the Verndale Substation was combined into one project in order to facilitate efficient coordination of engineering and construction. Due to the location of the existing Verndale Substation, the size of the existing property, and the configuration of the existing substation, site constraints would not allow for a substation modernization project to be safely and reliably implemented at the existing site. Therefore, the Verndale Substation Modernization Project involves rebuilding the Verndale Substation at a new location near the existing site and subsequently retiring the substation at its existing location.

Need Driver: The Verndale Substation serves Verndale, Staples, Wadena and the surrounding area, including customers of Minnesota Power, Great River Energy, and Missouri River Energy Services. The primary need driver for the Verndale Substation Modernization Project is age and condition of existing transformers, circuit breakers, disconnect switches, and site infrastructure. Much of the original equipment in this substation is nearing or beyond the end of its useful life, including many of the structures and foundations. In addition to these asset renewal concerns, historical Verndale Substation loading exceeds firm capacity for loss of a single 115/34 kV transformer, and transformer load-tap changers are needed to provide more effective distribution system voltage regulation.

Alternatives:

Transmission Alternatives

Install new 115/34 kV transformers at nearby Wing River 230/115 kV Substation and reconfigure distribution system to enable retirement of Verndale Substation.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition at the Verndale Substation.

Analysis: Across Minnesota Power’s system there are many transmission-to-distribution substations that require age-related upgrades. Much of the original equipment in these substations is nearing or beyond the end of its useful life. Minnesota Power’s Substation Modernization (Asset Renewal) Program involves coordinated replacement of end-of-life assets and holistic modernization improvements designed to extend the lives of these substations for the next several decades. The Program takes a holistic, site-by-site approach to facilitating the coordinated and efficient modernization of many aging substations throughout Minnesota Power’s system. In developing the scope for the Verndale Substation Modernization Project, Minnesota Power is considering the near-term and long-term needs of the area transmission and distribution system as well as the age and condition of existing site infrastructure and modern design standards for safety, accessibility, and maintainability.

Schedule: The project is currently planned as a multi-year project with construction taking place in 2027-2028.

General Impacts: The Verndale Substation Modernization Project will ensure a continuous and reliable power supply to the Verndale, Staples, and Wadena areas by increasing transformer capacity, improving voltage regulation, and replacing aging equipment before it fails.

Badoura 115 kV Substation Modernization

MPUC Tracking Number: 2021-NE-N5

Utility: Minnesota Power (MP)

Project Description: Move existing 115 kV lines from straight bus in original Badoura 115 kV Substation into the open positions on the newer Badoura #2 Substation 115 kV ring bus. Build out bus work to connect existing cap bank. Demo original Badoura 115 kV Substation including removal of old 115 kV box structure and control house. Adding new alternate station service source to replace feed from 34.5 kV equipment at the Badoura site.

Need Driver: Age and condition of Badoura 40L and 48L 115 kV breakers and control house. Shifting capacitor bank position to mitigate post-contingent low voltage following loss of shared breaker with 230/115 kV transformer.

Alternatives:

Transmission Alternatives

Replace the breakers in current locations and modernize original Badoura 115 kV Substation yard to retain existing box structure.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of 115 kV equipment at Badoura.

Analysis: The existing breakers protecting the two 115 kV lines into the straight bus at Badoura are 1960s-vintage oil breakers connected to a box structure of the same vintage. A newer ring bus was constructed adjacent to the original Badoura Substation in the 2000s as part of the Badoura 115 kV Project. The transmission lines connected to the original Badoura Substation are being relocated to open positions on the newer Badoura 115 kV ring bus to retire the original circuit breakers, box structure, and control house as well as establish a more reliable configuration for the 115 kV lines connected to the Badoura Substation.

Schedule: The project is scheduled to be completed in late 2025.

General Impacts: The Badoura 115 kV Modernization Project will improve safety and transmission system reliability around Badoura by relocating transmission lines from an aging 1960s era site and a straight bus configuration to a newer site in a ring bus configuration. The project will include small fence expansions to accommodate new line entrance equipment on the ring bus at the Badoura 115 kV site, but in general will make optimal use of the existing Badoura Substation site and enable retirement of most of the original Badoura Substation site.

Forbes 230 kV Modernization

MPUC Tracking Number: 2021-NE-N12

Utility: Minnesota Power (MP)

Project Description: Replace end-of-life 230/115 kV transformer and 230 kV capacitor bank, circuit breakers, switches, relay panels, and associated equipment at the Forbes 230 kV Substation.
Need Driver: Age and condition.

Alternatives:

Transmission Alternatives

There is no more economical or less impactful solution than replacing the existing substation equipment.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition at the Forbes 230 kV Substation.

Analysis: Across Minnesota Power’s system there are many transmission substations that require age-related upgrades. Much of the original equipment in these substations is nearing or beyond the end of its useful life. Minnesota Power’s Substation Modernization (Asset Renewal) Program involves coordinated replacement of end-of-life assets and holistic modernization improvements designed to extend the lives of these substations for the next several decades. The Program takes a holistic, site-by-site approach to facilitating the coordinated and efficient modernization of many aging substations throughout Minnesota Power’s system. At the Forbes 230 kV Substation, the circuit breaker is oil-filled from 1979, and one circuit breaker is an early generation SF6 model of concern. The existing capacitor bank has failed components and a larger replacement capacitor bank will provide additional voltage support to the transmission system. The 230/115 kV transformer is a critical transformer to the surrounding 115 kV system, including the East Range and the North Shore Loop. This transformer has many age and condition-related issues. An extended outage due to failure of this transformer would likely require running local peaking generation for the duration of the outage. There are concerns with moving the aging transformer from another site which has been identified as a spare in the event of failure. It is prudent to proactively replace this transformer in the near future before it fails.

Schedule: The project is presently planned for construction in 2027-2028.

General Impacts: The Forbes 230 kV Modernization Project will ensure that the Forbes 230 kV Substation continues to provide safe and reliable transmission support for Minnesota Power’s 230 kV and 115 kV transmission system. The impacts of the project will be entirely contained within the existing Forbes Substation yard, making optimal use of the existing infrastructure to reduce human and environmental impacts.

Cloquet Substation Modernization

MPUC Tracking Number: 2021-NE-N13

Utility: Minnesota Power (MP)

Project Description: The Cloquet Substation Modernization Project involves replacing aging electrical equipment, structures, and civil works at the existing Cloquet 115/14 kV Substation as part of Minnesota Power’s asset renewal program. Multiple substation asset renewal needs will be combined with necessary distribution transformer upgrades to make up the core of this project. This work at the Cloquet Substation was combined into one project in order to facilitate efficient coordination of engineering and construction. Due to the location of the existing Cloquet Substation near the St. Louis River, the size of the existing property, and the configuration of the existing substation, site constraints would not allow for a substation modernization project to be safely and reliably implemented at the existing site. Therefore, the Cloquet Substation Modernization Project involves rebuilding the Cloquet Substation at a new location east of the existing site and subsequently retiring the substation at its existing location.

Need Driver: The Cloquet Substation serves Cloquet, Esko, Scanlon, parts of the Fond Du Lac Reservation and the surrounding area. The primary need driver for the Cloquet Substation Modernization Project is age and condition of existing transformers, circuit breakers, disconnect switches, and site infrastructure. Much of the original equipment in this substation is nearing or beyond the end of its useful life, including many of the structures and foundations.

Alternatives:

Transmission Alternatives (None)

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition at the Cloquet Substation.

Analysis: Across Minnesota Power’s system there are many transmission-to-distribution substations that require age-related upgrades. Much of the original equipment in these substations is nearing or beyond the end of its useful life. Minnesota Power’s Substation Modernization (Asset Renewal) Program involves coordinated replacement of end-of-life assets and holistic modernization improvements designed to extend the lives of these substations for the next several decades. The Program takes a holistic, site-by-site approach to facilitating the coordinated and efficient modernization of many aging substations throughout Minnesota Power’s system. In developing the scope for the Cloquet Substation Modernization Project, Minnesota Power is considering the near-term and long-term needs of the area transmission and distribution system as well as the age and condition of existing site infrastructure and modern design standards for safety, accessibility, and maintainability.

Schedule: The project is currently planned as a multi-year project with construction taking place in stages from 2027-2028 to manage outage and constructability constraints.

General Impacts: The Cloquet Substation Modernization Project will ensure a continuous and reliable power supply to the Cloquet area by replacing aging equipment before it fails.

Boswell 115/23 kV Transformer Addition

Formerly “West Cohasset Substation”

MPUC Tracking Number: 2021-NE-N17

Utility: Minnesota Power (MP)

Project Description: Boswell 115/23 kV Transformer Addition Project involves adding a new 115/23 kV transformer at the Boswell 230/115 kV Substation and extending new 23 kV feeders from the substation.

Need Driver: The Boswell 115/23 kV Transformer Addition Project is necessary to upgrade the reliability and capacity of the existing 23 kV distribution system in the Cohasset area.

Alternatives:

Transmission Alternatives

Alternatives would be to install the new transformer at the nearby Boswell SES 115 kV Substation or to rebuild the Lind-Greenway Substation for increased capacity as well as upgrading the feeder tie between Lind-Greenway and Zemple substations to facilitate better backup capability.

Non-Wires Alternatives

Non-wire alternatives must be available when needed and dispatchable to support reliable load-serving under normal and contingency conditions.

Analysis: The Boswell 115/23 kV Transformer Project will enhance the reliability and capacity of the existing Minnesota Power 23 kV distribution system in the Cohasset area by improving backup capability between distribution sources and increasing reliable load-serving capacity in the area.

Schedule: The project is scheduled to be in service by the end of 2026.

General Impacts: The Boswell 115/23 kV Transformer Addition Project will make optimal use of an existing substation site to preserve and enhance the reliability of the Cohasset-area distribution system. Since the Boswell 230/115 kV Substation was originally designed to accommodate future expansion, including a transmission-distribution transformer, the majority of impacts from the substation expansion part of the project will be contained within the existing substation yard, minimizing human and environmental impacts.

56 Line Upgrade

MPUC Tracking Number: 2021-NE-N19

Utility: Minnesota Power (MP)

Project Description: Rebuild the existing Colbyville-Ridgeview 115 kV Transmission Line (56 Line) and increase its ratings.

Need Driver: Post-contingent overloads under certain system conditions identified in the MTEP analysis, as well as age and condition of existing structures and hardware.

Alternatives:

Transmission Alternatives

Reconductor existing line, build new parallel line.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of the transmission system in the area.

Analysis: This issue has been identified in MTEP and in Minnesota Power internal studies. The upgrade project provides the needed capacity increase as identified in the studies while also efficiently addressing asset renewal needs along the length of the line.

Schedule: The project is planned to be in service by end of year 2031.

General Impacts: The 56 Line Upgrade Project will provide necessary system improvements and asset renewal on Minnesota Power’s 115 kV system without requiring the establishment of additional transmission line corridors. During construction, MP and/or their contractors will be working in the area and will contribute positively to the local economy. No significant traffic impacts are anticipated. The right-of-way will be restored following construction.

Riverton 230 kV STATCOM

MPUC Tracking Number: 2021-NE-N21

Utility: Minnesota Power (MP)

Project Description: The Riverton 230 kV STATCOM Project involves the establishment of a new +300 Mvar STATCOM at the existing Riverton 230 kV Substation.

Need Driver: The new Riverton STATCOM is needed to ensure a continuous and reliable source of steady state and dynamic voltage support during times when no large dispatchable generators are online in Northern Minnesota.

Alternatives:

Transmission Alternatives

Must-run large dispatchable generators such as the Boswell Energy Center for reliability purposes. Retrofit one or more Boswell units with synchronous condenser capability.

Non-Wires Alternatives

STATCOMs are a non-wire alternative. Other non-wire alternatives must be dispatchable to respond when called upon, able to provide sufficient magnitude, consistency, and availability of system support, and located at an effective location to replace the support previously provided by baseload generators.

Analysis: The Boswell Energy Center units are the last remaining baseload generators operating in Northern Minnesota. As the last remaining baseload generators, the Boswell units provide voltage support and system strength on a continuous basis that support consistent and predictable system operations and properly function protection systems for the transmission system and the lower-voltage distribution systems that depend on it. In addition, Minnesota Power’s significant concentration of large industrial customers depend on predictable voltages and fault currents historically and presently provided by the Boswell units to support their large industrial processes and power quality needs. It is typical for large industrial plant design, like utility distribution system design, to take into account as a design basis the fault current contributions and normal operating voltages of the utility transmission system. Without the Boswell units online, the Northern Minnesota transmission system would operate for extended periods of time without any local generators online to provide fault current and voltage regulation. This mode of operation would be unprecedented in the modern history of the Northern Minnesota transmission system and, if not adequately assessed and mitigated, would lead to a great deal of uncertainty and potential degraded operation in the transmission system and lower-voltage industrial, municipal and Minnesota Power distribution system connected to it.

As Minnesota Power has continued to evaluate the issue and potential solutions, studies have consistently demonstrated significant degradation of steady state and dynamic voltage regulation when the Boswell units are offline. Less predictable steady state voltages, lower transient voltage dips during and after fault events, slower transient voltage recovery after fault events, and greater susceptibility to impacts from far-away regional fault events have all been identified as concerns on Minnesota Power’s system and propagating out on the regional 230 kV system. To address these concerns, a voltage support solution is needed to provide a continuous, predictable, and redundant source of steady state voltage regulation and dynamic voltage response on Minnesota Power’s 230 kV system. Based on Minnesota Power’s analysis and experience, a STATCOM is the ideal solution for meeting these steady state and dynamic voltage support needs. STATCOMs require no fuel for continuous operation and produce only reactive power. STATCOMs are capable of providing voltage regulation during normal system operations as well as dynamic voltage response during system disturbances. STATCOMs also provide inherently faster voltage response compared with Synchronous Condensers and are less maintenance intensive.

Minnesota Power conducted a study to identify the size and location that maximize the STATCOM benefits to the system. Based on this analysis, it was determined that a +300 (capacitive)/-300 (inductive) Mvar STATCOM located at the existing Riverton 230/115 kV Substation would provide the most benefit to the system in the form of steady-state and dynamic voltage support.

Schedule: Minnesota Power is presently working with the chosen STATCOM supplier to engineer, procure, and construct the ±300 Mvar STATCOM at the Riverton 230 kV Substation. Minnesota Power anticipates placing the Riverton STATCOM in service in mid-2028.

General Impacts: The establishment of one or more STATCOMs on Minnesota Power’s transmission system will provide necessary voltage support for Minnesota Power’s customers during times when no large dispatchable generators are online in Northern Minnesota. To the extent possible, new STATCOMs will be located at existing substation facilities. In addition to making optimal use of existing facilities, the establishment of one or more STATCOMs enables the transmission system to continue to operate reliably and predictably during and after changes in operation at the Boswell Energy Center that have social, environmental, and economic benefits. As a result, this project was initiated to install a ±300 Mvar STATCOM at the existing Riverton 230 kV Substation, which is centrally located in a historically weaker area of the Minnesota Power backbone 230 kV network to provide continuous steady-state and dynamic voltage support historically provided by baseload coal generators, such as the Boswell Energy Center. The Riverton STATCOM project will make optimal use of an existing substation site (Riverton) that was designed for future expansion, and the project will take place almost entirely on property already owned by Minnesota Power.

13 Line Rebuild

MPUC Tracking Number: 2021-NE-N23

Utility: Minnesota Power (MP)

Project Description: The 13 Line Rebuild Project involves replacement of transmission line structures and conductor on the Portage Lake – Riverton 115 kV Line (13 Line) due to age and condition. The project will also include the addition of shield wire and fiber-optic communications on the rebuilt transmission line.

Need Driver: The project will address asset renewal needs on 13 Line related to the age and condition of existing structures and transmission line components, add shield wire to improve reliability by reducing lightning-related outages that directly impact Minnesota Power and Great River Energy customers, and add fiber-optic communications to enhance transmission line protection systems.

Alternatives:

Transmission Alternatives

There are no reasonable alternatives that will address the asset renewal needs for the existing transmission line.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of the existing transmission line.

Analysis: Across Minnesota Power’s system there are many transmission lines that require age and condition-related upgrades. Many of the original wood pole structures and components on these transmission lines are nearing or beyond the end of their useful lives. As these transmission lines continue to age, the risk of structure and component failures – and therefore the risk of outages, property damage, and safety concerns – will increase. Minnesota Power’s Transmission Line Asset Renewal Program involves identification, prioritization, and coordination of transmission line asset renewal projects to address end-of-life wood poles and other components while holistically considering long-term reliability, capacity, and communications needs. The program is designed to extend the lives of these transmission lines so they can continue to reliably serve Minnesota Power’s customers and the region for many decades to come. In developing the scope for the 13 Line Rebuild Project, Minnesota Power also took into consideration reasonable enhancements that could be incorporated to improve operational performance and relaying for 13 Line.

Schedule: The 13 Line Rebuild Project is in early stages of project scoping and is presently targeted for phased construction beginning at the earliest in 2029. In reviewing the existing 13 Line and 158 Line (see Project 2023-NE-N6) transmission line corridor, Minnesota Power determined it would be prudent and necessary to file a Certificate of Need and Route Permit Application for the projects. Minnesota Power expects to file the application with the Commission in 2026.

General Impacts: The 13 Line Rebuild Project will ensure that the existing Portage Lake – Riverton 115 kV Line continues to provide a safe and reliable transmission path for Minnesota Power and Great River Energy’s customers and the region. The project involves replacement of existing assets on the existing transmission line right-of-way, therefore making optimal use of the existing transmission facilities with little or no additional human or environmental impacts.

Northland Reliability Project

MPUC Tracking Number: 2023-NE-N1

Utility: Minnesota Power (MP) & Great River Energy (GRE)

Project Description: Minnesota Power (MP) and Great River Energy (GRE) are jointly developing the Northland Reliability Project (Project), located in northern and central Minnesota. The Project consists of two major segments of transmission line construction:

Segment 1: construction of a new, approximately 140-mile long, double-circuit 345 kV transmission line connecting the existing Iron Range 500-230 kV Substation, a new Cuyuna 345 kV Series Compensation Station, and the existing Benton County 345 kV Substation, generally located near existing transmission line corridors; and
Segment 2: replacement of two existing 345 kV transmission lines
1. Replace an approximately 20-mile 230 kV line with two 345 kV circuits from the Benton County Substation to the new Big Oaks Substation along existing transmission corridors on double-circuit 345 kV structures. Approximately 6 miles of this double circuit line will have 69 kV underbuild; and
2. Replace an approximately 20-mile 345 kV line from the Benton County Substation to the existing Sherco Substation along existing transmission corridors using double-circuit capable 345 kV structures. Approximately 4 miles of this double circuit line will have a 69 kV circuit.

The Project will also involve the following new or modified substation and series compensation facilities:

Expansion of the existing Iron Range Substation 500-230 kV Substation, located near Grand Rapids, Minnesota, to include new 500-345 kV transformers, 345 kV bus and breakers, and 345 kV bus-connected shunt reactors
Construction of a new Cuyuna 345 kV Series Compensation Station located near Riverton, Minnesota, approximately at the midpoint of Segment 1
Expansion of the existing Benton County 345 kV Substation, located near St. Cloud, Minnesota, to include new 345 kV bus and breakers, and 345 kV bus connected shunt reactors

The proposed Big Oaks 345 kV Substation on the south end of Segment 2 is being permitted, engineered, and constructed by Xcel Energy as part of a separate project, and is not included in this scope of work.

Following the Commission’s route permit decision in February 2025, several underlying system improvements along the final Project route have also been incorporated into the scope of the Project. These underlying system improvements are necessary to maximize the extent to which the new double-circuit 345 kV transmission line can be co-located with and, in some cases, overtake existing rights-of-way. In many cases, the underlying system improvements involve replacement of existing assets that are nearing the end of their useful life, bringing additional asset renewal benefits into the Project. Major underlying system improvements involving the Riverton 230/115 kV Substation, Riverton 115/34 kV Substation, and associated 230 kV, 115 kV, 69 kV, and 34 kV lines are now planned as part of the Northland Reliability Project, along with rebuilding significant segments of the existing Blackberry – Riverton 230 kV Line, Grand Rapids – Riverton 115 kV Line, Riverton – Mud Lake 230 kV Line, and Benton County – Mud Lake 230 kV Line.

Need Driver: The Northland Reliability Project resolves regional reliability constraints resulting from the transition from fossil-fueled baseload generation to renewable energy generators, optimizes the ability to move power from one area to another, and contributes to significant regional transmission benefits associated with the MISO LRTP Tranche 1 portfolio. The Project is a foundational component of positioning the power system in northern Minnesota and the surrounding region for the clean energy transition, and it addresses some of the most challenging transmission system reliability issues from ceasing coal-fired operations and transitioning the baseload generator fleet, including serious regional voltage and transient stability issues. The Project was studied, reviewed, and ultimately approved as part of the MISO Long-Range Transmission Plan (LRTP) Tranche 1 Portfolio by MISO’s Board of Directors in July 2022.

Alternatives:

Transmission Alternatives

Transmission system alternatives are addressed in the Certificate of Need Application

Non-Wires Alternatives

Non-Wire Alternatives are addressed in the Certificate of Need Application.

Analysis: The need for the Northland Reliability Project and the benefits of the Project, as summarized in the Certificate of Need Application, are as follows:

The Project addresses severe regional voltage stability constraints associated with baseload generator fleet transition that have been identified in a multitude of studies over the course of the last decade. Without the Project, coal-fired baseload generation in northern Minnesota may need to continue operating to prevent significant reliability impacts from voltage stability constraints, including the need to potentially reduce northern Minnesota load by up to 1,000 megawatts (“MW”) in some cases.
The Project addresses significant transient stability constraints associated with baseload generator fleet transition and contributes to improved transient stability performance of the regional grid.
The Project addresses transmission line overloads related to baseload generator fleet transition. In the Applicants’ analysis, the Project relieves transmission line overloads on 83 circuits totaling 1,334 miles.
MISO identified that the Project is both a critical component of the regionally- beneficial LRTP Tranche 1 Portfolio and the most cost-effective solution to maintain reliability in central and northern Minnesota following the cessation of coal-fired operations at legacy fossil fuel units.

The Project provides many additional benefits to Minnesota Power’s customers and Great River Energy’s members, as well as the regional power system, including beneficial impacts on regional transfer capability, expected economic benefits in the energy market, resiliency and transmission source reliability, and future flexibility and electrification.

Schedule: The project is planned to be in service by June 1, 2030. Following the Commission’s February 2025 decision to grant a Certificate of Need and Route Permit for the Project, construction on the first segment of the Project began in the third quarter of 2025.

General Impacts: The project will be constructed along the existing 230 kV transmission line from the Iron Range substation to the Benton County substation, with additional construction along the existing 230 kV transmission line from the Benton County substation to the Monticello substation, terminating at the new Big Oaks substation, and construction along the existing 345 kV transmission line from the Benton County substation to the Sherco substation. The project is located in both forested and agricultural lands across its length. Construction is expected to be completed over 3 years. During this time, MP/GRE and/or their contractors will be working in the area and will contribute positively to the local economy. No significant traffic impacts are anticipated. The right-of-way will be restored following construction.

Maturi Substation Expansion

MPUC Tracking Number: 2023-NE-N4

Utility: Minnesota Power (MP)

Project Description: Expanding the existing Maturi 115/23 kV Substation to accommodate new 23 kV lines to serve local MP distribution loads, and replacing the existing tapped configuration with a more reliable breakered configuration by looping the transmission line in and out of the substation..

Need Driver: The Maturi Substation serves Minnesota Power customers in the Chisholm area and east of Hibbing. The primary need driver for the Maturi Substation Expansion project is to establish a closer source with added redundancy for distribution customers in and around the City of Chisholm and the surrounding area, and to unload adjacent 115/23 kV substations in anticipation of planned substation modernization projects.

Alternatives:

Transmission Alternatives

Establish a new 115/23 kV substation near Chisholm

Non-Wires Alternatives

Install new distribution-connected generation on the Chisholm area 23 kV system. Non- wire alternatives must be available when needed, dispatchable to support reliable load- serving under contingency conditions and have an output characteristic sufficient to reduce the effective peak load in the area.

Analysis: The 23 kV system in the Chisholm area is currently served by a long 23 kV feeder from the Hibbing Substation, with a backup source on an even longer feeder from the Virginia Substation. Both of these substations are scheduled for modernization projects as part of Minnesota Power’s asset renewal program. Moving the Chisholm area to a closer source from the nearby Maturi Substation will improve reliability and resiliency of the local 23 kV system, enhance redundancy and load-serving capacity for Maturi, Hibbing, and Virginia, and enable reliable construction of the planned modernization projects at the adjacent substations.

Schedule: The project is planned to be in service by end of year 2026.

General Impacts: The Maturi Expansion Project will ensure a continuous and reliable power supply to the City of Chisholm and the surrounding area. Since the Maturi Substation was designed originally to accommodate two distribution transformers, the majority of impacts from the substation modifications will be contained within the existing Maturi Substation yard, making optimal use of the existing infrastructure to reduce human and environmental impacts. The project also involves looping 25 Line in and out of the substation on the existing transmission line right- of-way, therefore making optimal use of the existing transmission line with little or no additional human or environmental impacts.

Mahtowa Substation Expansion

MPUC Tracking Number: 2023-NE-N5

Utility: Minnesota Power (MP)

Project Description: The Mahtowa Substation Expansion Project involves replacing aging electrical equipment, structures, and civil works at the existing Mahtowa 115/46 kV Substation as part of Minnesota Power’s asset renewal program. The project also includes reliability improvements including expansion of the Mahtowa Substation and conversion of the low-side distribution voltage to 34.5 kV to facilitate reliable back-up connection to feeders in the Cloquet area as well as efficient operations and maintenance from a more standard distribution voltage. Mahtowa Substation is currently connected in a tapped configuration to the existing 26 Line that connects Thomson to Cromwell. This project will also include reconfiguring this connection into a more reliable breakered configuration, resulting in two different lines so that the Mahtowa substation is no longer a radial tap.

Need Driver: The Mahtowa Substation serves Minnesota Power customers along the Interstate 35 corridor between Cloquet and Hinckley. The primary need driver for the Mahtowa Substation Expansion Project is age and condition of the existing transformer and site infrastructure. Much of the original equipment in this substation is nearing or beyond the end of its useful life, including many of the structures and foundations. In addition to these asset renewal concerns, Minnesota Power has developed a program to convert the distribution system in the area from the non- standard 46 kV operating voltage to the standard 34.5 kV operating voltage, facilitating more reliable connections to adjacent sources and more efficient operations and maintenance from the standardized distribution network voltage. The voltage conversion will also enable implementation of a feeder automation project resulting in enhanced FLISR (fault location isolation and restoration) for the 34.5 kV feeder connection between Mahtowa and Cloquet.

Alternatives:

Transmission Alternatives

There is no more economical or less impactful solution than replacing the existing substation the existing site.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition at the Mahtowa Substation.

Analysis: Across Minnesota Power’s system there are many transmission-to-distribution substations that require age-related upgrades. Much of the original equipment in these substations is nearing or beyond the end of its useful life. Minnesota Power’s Substation Modernization (Asset Renewal) Program involves coordinated replacement of end-of-life assets and holistic modernization improvements designed to extend the lives of these substations for the next several decades. The Program takes a holistic, site-by-site approach to facilitating the coordinated and efficient modernization of many aging substations throughout Minnesota Power’s system. In developing the scope for the Mahtowa Substation Expansion Project, Minnesota Power is considering the near-term and long-term needs of the area transmission and distribution system as well as the age and condition of existing site infrastructure and modern design standards for safety, accessibility, and maintainability, including conversion to a standard distribution voltage.

Schedule: The project is planned for construction starting in 2026 with a targeted in-service date in 2028.

General Impacts: The 115/23 kV transformer located at Mahtowa has reached its end of life and poses a reliability issue. This transformer and the 115/46 kV transformer also at this site will be replaced with a single 115/34 kV transformer. This will increase the reliability of this site, remove the last of the 23 kV voltage class in the Minnesota Power central area, and progress Minnesota Power’s efforts to convert from the non-standard 46 kV voltage class to the standard 34.5 kV voltage class. This will help keep the distribution system consistent in the area for operation and maintenance and enhanced connections to adjacent sources. Second, this project will loop 26 Line in and out of the substation to remove Mahtowa as a radial tap. The project will make optimal use of existing infrastructure at the Mahtowa Substation site to reduce human and environmental impacts.

158 Line Rebuild

MPUC Tracking Number: 2023-NE-N6

Utility: Minnesota Power (MP)

Project Description: The 158 Line Rebuild Project involves replacement of transmission line structures and conductor on the Portage Lake – Cromwell 115 kV Line (“158 Line”) due to age and condition. The project will also include the addition of shield wire and fiber-optic communications on the rebuilt transmission line.

Need Driver: The project will address asset renewal needs on 158 Line related to the age and condition of existing structures and transmission line components, add shield wire to improve reliability by reducing lightning-related outages that directly impact Minnesota Power and Great River Energy customers, and add fiber-optic communications to enhance transmission line protection systems.

Alternatives:

Transmission Alternatives

There are no reasonable alternatives that will address the asset renewal needs for the existing transmission line.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of the existing transmission line.

Analysis: Across Minnesota Power’s system there are many transmission lines that require age and condition-related upgrades. Many of the original wood pole structures and components on these transmission lines are nearing or beyond the end of their useful lives. As these transmission lines continue to age, the risk of structure and component failures – and therefore the risk of outages, property damage, and safety concerns – will increase. Minnesota Power’s Transmission Line Asset Renewal Program involves identification, prioritization, and coordination of transmission line asset renewal projects to address end-of-life wood poles and other components while holistically considering long-term reliability, capacity, and communications needs. The program is designed to extend the lives of these transmission lines so they can continue to reliably serve Minnesota Power’s customers and the region for many decades to come. In developing the scope for the 158 Line Rebuild Project, Minnesota Power also took into consideration reasonable enhancements that could be incorporated to improve operational performance and relaying for 158 Line.

Schedule: The 158 Line Rebuild Project is in early stages of project scoping and is presently targeted for 1-2 years of phased construction beginning at the earliest in 2028. In reviewing the existing 13 Line (see Project 2021-NE-N23) and 158 Line transmission line corridor, Minnesota Power determined it would be prudent and necessary to file a combined Certificate of Need and Route Permit Application for the projects. Minnesota Power expects to file the application with the Commission in 2026.

General Impacts: The 158 Line Rebuild Project will ensure that the existing Portage Lake – Riverton 115 kV Line continues to provide a safe and reliable transmission path for Minnesota Power and Great River Energy’s customers and the region. The project involves replacement of existing assets on the existing transmission line right-of-way, therefore making optimal use of the existing transmission facilities with little

Arrowhead 115 kV Single Point of Failure

MPUC Tracking Number: 2023-NE-N7

Utility: Minnesota Power (MP)

Project Description: The scope of this project at the Arrowhead 115 kV Substation includes installing a new alarm for the DC battery in case of an open circuit, redundant control wiring where applicable to ensure redundant pathways, installing a redundant DC power supply, and any associated relay panel replacements.

Need Driver: The existing NERC TPL-001standard is a transmission planning requirement aimed at ensuring that the bulk electric system (BES) can operate reliably across a broad range of system conditions and faults. Within the standard, Category P5 focuses on the impacts of a contingency that results from the failure of a non-redundant component of a Protection System with delayed fault clearing. Through the annual MISO Transmission Expansion Plan (MTEP), it was determined that a Category P5 fault at the Arrowhead 115 kV Substation bus resulted in significant violations across the system. As a result, a project was initiated to address any non-redundant components in the Protection System at the Arrowhead 115 kV Substation.

Alternatives:

Transmission Alternatives

There would need to be significant existing transmission line rebuild to upgrade to a larger conductor that would mitigate all violations present after the Category P5 contingency.

Non-Wires Alternatives

The Category P5 contingency can only be mitigated by adding Protection System redundancy or upgrading affected transmission system components.

Analysis: Adding redundancy to the components of the Arrowhead 115 kV Protection System is a more cost-effective system resiliency solution compared to rebuilding transmission lines.

Schedule: The project is planned to be in service by end of year 2026.

General Impacts: This project will introduce redundant Protection System components at the Arrowhead 115 kV Substation. At the end of this project, the Arrowhead 115 kV P5 contingencies can be retired due to the redundant Protection System components at the site. The majority of impacts from the project will be contained within the existing Arrowhead 115 kV Substation yard, making optimal use of the existing infrastructure to reduce human and environmental impacts.

Forbes 115 kV Single Point of Failure

MPUC Tracking Number: 2023-NE-N8

Utility: Minnesota Power (MP)

Project Description: The scope of this project at the Forbes 115 kV Substation includes installing a new alarm for the DC battery in case of an open circuit, redundant control wiring where applicable to ensure redundant pathways, installing a redundant DC power supply, and any associated relay panel replacements.

Need Driver: The NERC TPL-001-5.1 standard is a transmission planning requirement aimed at ensuring that the bulk electric system (BES) can operate reliably across a broad range of system conditions and faults. Within the standard, Category P5 focuses on the impacts of a contingency that results from the failure of a non-redundant component of a Protection System with delayed fault clearing. Through the annual MISO Transmission Expansion Plan (MTEP), it was determined that a Category P5 fault at the Forbes 115 kV Substation bus resulted in significant violations across the system. As a result, a project was initiated to address any non-redundant components in the Protection System at the Forbes 115 kV Substation.

Alternatives:

Transmission Alternatives

There would need to be significant existing transmission line rebuild to upgrade to a larger conductor that would mitigate all violations present after the Category P5 contingency.

Non-Wires Alternatives

The Category P5 contingency can only be mitigated by adding Protection redundancy or upgrading affected transmission system components.

Analysis: This is a cost-effective system resiliency solution.

Schedule: The project is planned to be in service by end of year 2027.

General Impacts: This project will introduce Protection System components at the Forbes 115 kV Substation site. At the end of the project, the Forbes 115 kV P5 contingencies can be retired due to the redundant Protection System components monitoring at the site. The majority of impacts from the project will be contained within the existing Forbes 115 kV Substation yard, making optimal use of the existing infrastructure to reduce human and environmental impacts.

Ridgeview 115/34 kV Transformer Addition

MPUC Tracking Number: 2023-NE-N9

Utility: Minnesota Power (MP)

Project Description: Expanding the Ridgeview 115 kV Substation to add a new 115/34 kV transformer, establishing a new source to the local 34.5 kV distribution system.

Need Driver: Distribution reliability capacity, and backup capability, including reliability enhancements on the Duluth 34.5 kV distribution system.

Alternatives:

Transmission Alternatives

Establish a new 115/34 kV substation in Central Duluth or build additional 34.5 kV feeders from existing sources at Swan Lake Road and 15th Avenue West.

Non-Wires Alternatives

Install new distribution-connected generation on the Duluth-area 34.5 kV system. Non- wire alternatives must be available when needed, dispatchable to support reliable load-serving under contingency conditions and have an output characteristic sufficient to reduce the effective peak load in the area.

Analysis: The Duluth 34 kV distribution system has sources at the Swan Lake Road, 15th Avenue West, and LSPI substations, but the majority of the load is located near the midpoint of the 34 kV system in downtown Duluth and the medical district – relatively far from the existing Swan Lake Road and LSPI substation sources. The 34 kV system was originally developed due to the significant challenges associated with the development of additional transmission-distribution substations in central and downtown Duluth. The 34 kV system also provides enhanced reliability to critical loads such as the hospitals by placing them on a high-capacity backbone system with automated fault location, isolation, and system restoration (FLISR) implemented. As more load has transitioned onto the 34 kV system, backing up the entire system from either LSPI or Swan Lake Road has become more challenging due to the feeder distance from the sources to the load. Additional load growth following near-term expansion of one of the two major hospitals in the medical district will further impact backup capability for the Duluth 34 kV system. The 15th Avenue West source was recently established to address these concerns, but the loss of this source is already becoming a reliability concern when significant amounts of downtown-area load are served from the backup source at Swan Lake Road. The addition of a new 115/34 kV transformer at the Ridgeview Substation, which is located much closer to the main Duluth 34 kV system loads, and integration of the new source into the automated 34 kV feeder system will ensure that the Duluth 34 kV system continues to be a very reliable source with sufficient load-serving capability for critical loads in Duluth. The addition of the Ridgeview source will also enable additional stepdowns to be established on the 34 kV system, shifting load off the heavily-loaded 14 kV system, enhancing backup capability, and allowing for more reliable construction of substation modernization projects at the main 115/14 kV substations in the Duluth area.

Schedule: The project is planned to be in service by end of year 2027.

General Impacts: The Ridgeview Transformer Addition Project will preserve and enhance the reliability of the Duluth 34 kV distribution system. Since the Ridgeview Substation was designed originally to accommodate the transformer addition, the majority of impacts from the substation expansion part of the project will be contained within the existing Ridgeview Substation yard, making optimal use of the existing infrastructure to reduce human and environmental impacts.

Wrenshall Substation Modernization

MPUC Tracking Number: 2023-NE-N10

Utility: Minnesota Power (MP)

Project Description: The Wrenshall Substation Modernization Project involves replacing aging electrical equipment, structures, and civil works at the existing Wrenshall 115/14 kV Substation as part of Minnesota Power’s asset renewal program. Multiple substation asset renewal needs will be combined with necessary distribution transformer upgrades to make up the core of this project. This work at the Wrenshall Substation was combined into one project in order to facilitate efficient coordination of engineering and construction.

Need Driver: The Wrenshall Substation serves Minnesota Power customers in the rural areas around Wrenshall and Carlton. The primary need driver for the Wrenshall Substation Modernization Project is age and condition of the existing transformer and site infrastructure, some of which is constructed on wood pole structures. Much of the original equipment in this substation is nearing or beyond the end of its useful life, including many of the structures and foundations. The modernization of the Wrenshall Substation will also result in improved reliability for customers in the area and position the substation to support feeder automation, stronger ties to adjacent distribution infrastructure, future load growth, and distributed energy resource integration.

Alternatives:

Transmission Alternatives

There is no more economical or less impactful solution than replacing the existing substation on the existing site.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition at the Wrenshall Substation.

Analysis: Across Minnesota Power’s system there are many transmission-to-distribution substations that require age-related upgrades. Much of the original equipment in these substations is nearing or beyond the end of its useful life. Minnesota Power’s Substation Modernization (Asset Renewal) Program involves coordinated replacement of end-of-life assets and holistic modernization improvements designed to extend the lives of these substations for the next several decades. The Program takes a holistic, site-by-site approach to facilitating the coordinated and efficient modernization of many aging substations throughout Minnesota Power’s system. In developing the scope for the Wrenshall Substation Modernization Project, Minnesota Power is considering the near-term and long-term needs of the area transmission and distribution system as well as the age and condition of existing site infrastructure and modern design standards for safety, accessibility, and maintainability.

Schedule: The project is planned to be in service by end of year 2029.

General Impacts: This project will ensure a continuous and reliable power supply to the Wrenshall area by replacing old assets prior to failure. The project will make optimal use of the existing Wrenshall Substation site to reduce human and environmental impacts.

133 Line Rebuild

MPUC Tracking Number: 2023-NE-N11

Utility: Minnesota Power (MP)

Project Description: Rebuild the existing Verndale – Wing River 115 kV Transmission Line (133 Line) and increase its ratings.

Need Driver: Post-contingent overloads under certain system conditions identified in the MTEP analysis, as well as age and condition of existing structures and hardware.

Alternatives:

Transmission Alternatives

Reconductor existing line, build new parallel line.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of the transmission system in the area.

Schedule: The project is planned to be in service by end of year 2028.

General Impacts: The 133 Line Upgrade Project will provide necessary system improvements and asset renewal on Minnesota Power’s 115 kV system without requiring the establishment of additional transmission line corridors. During construction, MP and/or their contractors will be working in the area and will contribute positively to the local economy. No significant traffic impacts are anticipated. The right-of-way will be restored following construction.

Maple River – Cuyuna 345 kV Project

LRTP Project #20

MPUC Tracking Number: 2025-NE-N1

Utility: Minnesota Power (MP), Otter Tail Power (OTP), and Great River Energy (GRE)

Project Description: Minnesota Power (MP), Otter Tail Power (OTP), and Great River Energy (GRE) are jointly developing the Maple River – Cuyuna 345 kV Project, located in northern Minnesota. The Project consists of the construction of a new, approximately 165-mile, single circuit 345 kV transmission line connecting the MP Cuyuna 345 kV Substation to the OTP Maple River 345 kV Substation in North Dakota. This single circuit transmission line will be built on double-circuit capable structures with both circuits strung and jumpered together to meet design requirements specified by MISO and provide a high-capacity, low-impedance west-to-east transmission corridor from eastern North Dakota through central/northern Minnesota. This Project will also involve modifications to the following existing substations:

Expansion of the Cuyuna 345 kV Substation, located near Riverton, Minnesota, to include an additional 345 kV line exit and shunt reactor.
Expansion of the Maple River Substation, located near Fargo, North Dakota, to include an additional 345 kV line exit and shunt reactor.

Need Driver: The Project was studied, reviewed, and ultimately approved as a part of the MISO Long-Range Transmission Plan (LRTP) Tranche 2.1 Portfolio by MISO’s Board of Directors in December 2024. As a part of this larger portfolio, the Project will enhance the reliability of the local and regional transmission system as the way electricity is produced and is used changes, increase transmission system capacity to reliably deliver energy from where it is produced to where it is used, meet growing electrical demand, enhance resiliency during extreme weather events, and enable cost-effective regional energy transfers supporting economical grid operations.

Alternatives:

Transmission Alternatives

Transmission system alternatives will be addressed in the Certificate of Need Application.

Non-Wires Alternatives

Non-Wire Alternatives will be addressed in the Certificate of Need Application.

Analysis: The need for the Maple River – Cuyuna 345 kV Project and the benefits of the Project will be summarized in the Certificate of Need Application. The project resolves regional voltage and transient stability issues, relieves transmission line overloads, and mitigates low voltage violations, in addition to increasing regional transfer capability and local load-serving capability. It also enables additional generation interconnection and delivery capability and helps reduce energy curtailments by strengthening the transmission backbone and improving system flexibility.

Schedule: The Project is planned to be in service by June 1, 2033.

General Impacts: While the Project is still in the early stages of routing in Minnesota and North Dakota, it is anticipated that the new transmission line will largely follow existing utility corridors to minimize establishment of new rights-of-way and to help navigate the varying land use and space constraints throughout the Project area. MP, OTP, and GRE are taking into consideration all relevant human, environmental, and commercial interests in the area and actively engaging impacted stakeholders in routing and siting of the project. Construction is anticipated to take three to four years to complete. During this time, MP, OTP, and GRE and/or their contractors will be working in the area and will contribute positively to the local economy. The right-of-way will be restored following construction.

Iron Range – St. Louis County – Arrowhead 345 kV Project

LRTP Project #21

MPUC Tracking Number: 2025-NE-N2

Utility: Minnesota Power (MP), American Transmission Company (ATC)

Project Description: Minnesota Power (MP) and American Transmission Company (ATC) are jointly developing the Iron Range – St. Louis County – Arrowhead (ISA) Project, located in northern Minnesota. The Project consists of two major segments of transmission line construction:

Iron Range – St. Louis County 345 kV Line: construction of a new, approximately 63-mile, single circuit 345 kV transmission line connecting the MP Iron Range 345 kV Substation to the MP St. Louis County 345 kV Substation. This single circuit transmission line will be built on double-circuit capable structures.
St. Louis County – Arrowhead 345 kV Line: construction of a new, approximately 1-mile, double circuit 345 kV transmission line connecting the MP St. Louis County 345 kV Substation to the ATC Arrowhead 345 kV Substation.

This Project will also involve the following modified substation facilities:

Expansion of the MP Iron Range 345 kV Substation, located near Grand Rapids, Minnesota, to include an additional 345 kV transmission line exit
Expansion of the MP St. Louis County 345 kV Substation, located in Hermantown, Minnesota to include three additional 345 kV transmission line exits
Expansion of the ATC Arrowhead 345 kV Substation, located in Hermantown, Minnesota, to include two additional 345 kV transmission line exits

Need Driver: The Project was studied, reviewed, and ultimately approved as a part of the MISO Long-Range Transmission Plan (LRTP) Tranche 2.1 Portfolio by MISO’s Board of Directors in December 2024. As a part of this larger portfolio, the Project will enhance the reliability of the local and regional transmission system as the way electricity is produced and is used changes, increase transmission system capacity and regional transfer capability to reliably deliver energy from where it is produced to where it is used, meet growing electrical demand, enhance resiliency during extreme weather events, and enable cost-effective regional energy transfers supporting economical grid operations.

Alternatives:

Transmission Alternatives

Transmission system alternatives will be addressed in the Certificate of Need Application.

Non-Wires Alternatives

Non-Wire Alternatives will be addressed in the Certificate of Need Application.

Analysis: The need for the Iron Range – St. Louis County – Arrowhead 345 kV Project and the benefits of the Project will be summarized in the Certificate of Need Application. The project improves transmission system performance for regional voltage and transient stability issues, optimizes regional transfer capability, enhances transmission system resiliency and reliability, and increases local load-serving capability.

Schedule: The Project is currently planned to be in service by June 1, 2032.

General Impacts: While the project is still in the early stages of routing, it is anticipated that the new transmission line will largely follow or overtake existing utility corridors to minimize establishment of new rights-of-way and to help navigate the varying land use and space constraints throughout the project area. MP and ATC are taking into consideration all relevant human, environmental, and commercial interests in the area and actively engaging impacted stakeholders in routing and siting of the project. Construction is anticipated to take two to three years to complete. During this time, MP and ATC and/or their contractors will be working in the area and will contribute positively to the local economy. The right-of-way will be restored following construction.

24 Line Rebuild

MPUC Tracking Number: 2025-NE-N3

Utility: Minnesota Power (MP)

Project Description: Rebuild the existing Verndale – Dog Lake 115 kV Transmission Line (24 Line) and increase its ratings.

Need Driver: Post-contingent overloads under certain system conditions identified in the MTEP analysis, as well as age and condition of existing structures and hardware.

Alternatives:

Transmission Alternatives

Reconductor existing line, build new parallel line.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of the transmission system in the area.

Schedule: The project is planned to be in service by end of year 2029.

General Impacts: The 24 Line Upgrade Project will provide necessary system improvements and asset renewal on Minnesota Power’s 115 kV system without requiring the establishment of additional transmission line corridors. During construction, MP and/or their contractors will be working in the area and will contribute positively to the local economy. No significant traffic impacts are anticipated. The right-of-way will be restored following construction.

Arrowhead 230 kV EEE Replacement

MPUC Tracking Number: 2025-NE-N4

Utility: Minnesota Power (MP)

Project Description: The Arrowhead 230 kV EEE Replacement Project will replace the existing 230 kV EEE due to age and condition and includes improvements to mitigate potential single points of failure in the control and protection infrastructure of the Arrowhead 230 kV Substation. These improvements will include installing redundant control wiring where applicable to ensure redundant pathways, installing a redundant DC power supply, relay panel replacements, new cable trench, and making space for future projects panels that would not fit into the old EEE.

Need Driver: The existing NERC TPL-001-5.1 standard is a transmission planning requirement aimed at ensuring that the bulk electric system (BES) can operate reliably across a broad range of system conditions and faults. Within the standard, Category P5 focuses on the impacts of a contingency that results from the failure of a non-redundant component of a Protection System with delayed fault clearing. Through the annual MISO Transmission Expansion Plan (MTEP), it was determined that a Category P5 fault located at the Arrowhead 230 kV Substation bus resulted in significant violations across the system. As a result, a project was initiated to address any non- redundant components in the Protection System at the Arrowhead 230 kV Substation. The existing Arrowhead 230 kV building is also reaching its end-of-life and is experiencing issues with wildlife chewing circuitry cables.

Alternatives:

Transmission Alternatives

There would need to be significant existing transmission line rebuilds to upgrade to a larger conductor that would mitigate all violations present after the Category P5 contingency. A transmission alternative would also not address the age and condition need of the EEE building, which is reaching its end-of-life and is experiencing issues with wildlife management.

Non-Wires Alternatives

The Category P5 contingency can only be mitigated by adding Protection System redundancy or upgrading affected transmission system components.

Analysis: Adding redundancy to the components of the Arrowhead 230 kV Protection System is a more cost-effective system resiliency solution compared to rebuilding transmission lines or building new transmission lines.

Schedule: The project is planned to be constructed in 2026 – 2027.The new EEE will be placed in service by the end of the year 2027. Between 2027-2029, among other projects occurring at the Arrowhead 230 kV Substation, panels will be cut over from the old EEE to the new EEE and the old EEE building will be demolished in 2029.

General Impacts: This project will introduce redundant Protection System components at the Arrowhead 230 kV Substation and address the age and condition concerns for the Arrowhead 230 kV EEE building. At the end of the project, the Arrowhead 230 kV P5 contingencies can be retired due to the redundant Protection System components at the site. The majority of impacts from the project will be contained within or immediately adjacent to the existing Arrowhead 230 kV Substation yard, making optimal use of the existing infrastructure to reduce human and environmental impacts.

Transmission Line Pole Replacement 2025

MPUC Tracking Number: 2025-NE-N5

Utility: Minnesota Power (MP)

Project Description: This project will replace or modify wood pole transmission structures on 53 existing transmission lines across the Minnesota Power footprint. Where possible, C-Trusses will be added to the structures to stabilize minor issues, otherwise full pole or structure replacements are anticipated.

Need Driver: Through routine groundline inspections of the transmission lines, wood pole structures were identified as in need of repair or replacement due to age or condition.

Alternatives:

Transmission Alternatives

There is no more economical or less impactful solution than replacing the existing wood poles on the existing transmission lines.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of the transmission system in the area.

Analysis: Across Minnesota Power’s system there are many transmission lines that require age and condition-related upgrades. Many of the original wood pole structures and components on these transmission lines are nearing or beyond the end of their useful lives. As these transmission lines continue to age, the risk of structure and component failures – and therefore the risk of outages, property damage, and safety concerns – will increase. Minnesota Power’s Transmission Line Asset Renewal Program involves identification, prioritization, and coordination of transmission line asset renewal projects to address end-of-life wood poles and other components while holistically considering long-term reliability, capacity, and communications needs. The program is designed to extend the lives of these transmission lines so they can continue to reliably serve Minnesota Power’s customers and the region for many decades to come. In developing the pole replacement program, Minnesota Power has taken into consideration the condition of wood poles based on field surveys, as well as the near-term and long-term needs for the transmission lines involved, targeting the highest-priority pole replacements for continued safe and reliable operation of the transmission lines.

Schedule: This project is targeted for completion by the end of the year 2025.

General Impacts: This project will enhance the safety and reliability of the transmission system by replacing or stabilizing aging and damaged structures across northeastern Minnesota. The project involves replacement of existing assets on the existing transmission line right-of-way, therefore making optimal use of the existing transmission facilities with little or no additional human or environmental impacts.

Iron Range 500 kV Reactor Addition

MPUC Tracking Number: 2025-NE-N6

Utility: Minnesota Power (MP)

Project Description: This project will add a third line-connected 150 MVAR reactor at the Iron Range 500 kV Substation. This will add a redundant reactor to the substation to allow for better voltage control during routine maintenance and extend the life of the existing reactors.

Need Driver: During circumstances where one reactor is out of service, operation of the 500 kV system with a single reactor may put stress on the remaining reactor under some conditions where system voltages are higher, leading to accelerated aging of the reactor. The addition of the third reactor ensures two reactors will be available, even when one of the reactors at the station is unavailable, and provides a spare in case of a reactor failure.

Alternatives:

Transmission Alternatives

This is an asset renewal issue to ensure optimal life cycle aging of the existing 500 kV reactors at the site and provide redundancy in case of a failure. Other voltage control solutions such as STATCOMs are significantly more expensive.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to the accelerated ageing, redundancy and reliability of critical transmission assets.

Analysis: Shunt reactors are installed at the Iron Range 500 kV Substation to control 500 kV system voltages during light loading conditions and to enable safe and reliable energization of the transmission line. When in service, the reactors absorb reactive power, helping to reduce the system voltage during times of high voltage. Very high voltages can cause the reactors to operate near their design limits, particularly when they occur during moderate to high ambient temperatures, causing heating and potentially reducing the useful life of the reactors. This accelerated aging can lead to premature failures. In the event of a reactor failure, the remaining reactor would see significant stress until a replacement can be installed, potentially subjecting that reactor to earlier failure as well. To limit loss of life and provide needed redundancy, the addition of a third reactor will ensure that two reactors are available practically at all times and reduce the stress placed on the existing reactors during high voltage system conditions.

Schedule: This project is planned to be in service by the end of the year 2030.

General Impacts: This project will increase reliability of the system by allowing for better voltage control during maintenance activities or unplanned outages while also enhancing the lifespan of the existing reactors. The majority of impacts from the project will be contained within or immediately adjacent to the existing Iron Range 500 kV Substation yard, making optimal use of the existing infrastructure to reduce human and environmental impacts.

Shannon Capacitor Bank Replacement

MPUC Tracking Number: 2025-NE-N7

Utility: Minnesota Power (MP)

Project Description: The 115 kV capacitor bank located on the Shannon 115 kV bus will be replaced with a new standard-sized capacitor bank and relocated for safer and easier access to maintenance crews to access. The two capacitor banks on the Shannon 230 kV bus will also be replaced due to their age with standardized capacitor bank size and configurations.

Need Driver: The capacitor bank located on the Shannon 115 kV Substation is over 50 years old, has been progressively failing, and is located in a spot that is difficult for maintenance crews to replace failed cans. Additionally, all three capacitor banks located at the Shannon Substation, one on the 115 kV and two on the 230 kV, are of a type and size that is no longer a standard for Minnesota Power. Because of the age of all three capacitor banks, and the actively failing Shannon 115 kV capacitor bank, all three need to be replaced in order to maintain reliable transmission voltage support.

Alternatives:

Transmission Alternatives

There are no transmission alternatives to replacing the aging and non-MP standard assets at the existing Shannon 230/115 kV Substation.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of the transmission assets in the area.

Schedule: This project is planned to be in service by the end of the year 2026.

General Impacts: This project will replace aging transmission assets to ensure continuous and reliable voltage support. The impacts of the project will be entirely contained within the existing Shannon Substation yard, making optimal use of the existing infrastructure to reduce human and environmental impacts.

26 Line Rebuild

MPUC Tracking Number: 2025-NE-N8

Utility: Minnesota Power (MP)

Project Description: The 26 Line Rebuild Project involves replacement of transmission line structures and conductor on the Thomson – Mahtowa - Cromwell 115 kV Line (26 Line) due to age and condition. The project will also include the addition of shield wire and fiber-optic communications on the rebuilt transmission line.

Need Driver: The project will address asset renewal needs on 26 Line related to the age and condition of existing structures and transmission line components, add shield wire to improve reliability by reducing lightning-related outages that directly impact Minnesota Power and Great River Energy customers, and add fiber-optic communications to enhance transmission line protection systems.

Alternatives:

Transmission Alternatives

There are no reasonable alternatives that will address the asset renewal needs for the existing transmission line.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of the transmission system in the area.

Analysis: Across Minnesota Power’s system there are many transmission lines that require age and condition-related upgrades. Many of the original wood pole structures and components on these transmission lines are nearing or beyond the end of their useful lives. As these transmission lines continue to age, the risk of structure and component failures – and therefore the risk of outages, property damage, and safety concerns – will increase. Minnesota Power’s Transmission Line Asset Renewal Program involves identification, prioritization, and coordination of transmission line asset renewal projects to address end-of-life wood poles and other components while holistically considering long-term reliability, capacity, and communications needs. The program is designed to extend the lives of these transmission lines so they can continue to reliably serve Minnesota Power’s customers and the region for many decades to come. In developing the scope for the 26 Line Rebuild Project, Minnesota Power also took into consideration reasonable enhancements that could be incorporated to improve operational performance and relaying for 26 Line.

Schedule: The 26 Line Rebuild Project is in early stages of project scoping and is presently targeted for 3-4 years of phased construction beginning at the earliest in 2030.

General Impacts: The 26 Line Rebuild Project will ensure that the existing Thomson – Mahtowa – Cromwell 115 kV Line continues to provide a safe and reliable transmission path for Minnesota Power and Great River Energy’s customers and the region. The project involves replacement of existing assets on the existing transmission line right-of-way, therefore making optimal use of the existing transmission facilities with little or no additional human or environmental impacts.

Haines Road Substation Modernization

MPUC Tracking Number: 2025-NE-N9

Utility: Minnesota Power (MP)

Project Description: The Haines Substation Modernization Project involves replacing aging electrical equipment, structures, and civil works at the existing Haines Road 115/14 kV Substation as part of Minnesota Power’s asset renewal program. Multiple substation asset renewal needs will be combined with necessary distribution transformer upgrades to make up the core of this project. This work at the Haines Road Substation was combined into one project to facilitate efficient coordination of engineering and construction.

Need Driver: The Haines Road Substation serves the central part of Duluth, including the Miller Hill Mall, as well as Hermantown and the surrounding area. The primary need driver for the Haines Road Substation Modernization Project is age and condition of existing transformers, circuit breakers, disconnect switches, switchgear, and site infrastructure. Much of the original equipment in this substation is nearing or beyond the end of its useful life, including many of the structures and foundations.

Alternatives:

Transmission Alternatives (None)

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of the transmission and distribution system in the area.

Analysis: Across Minnesota Power’s system there are many transmission-to-distribution substations that require age-related upgrades. Much of the original equipment in these substations is nearing or beyond the end of its useful life. Minnesota Power’s Substation Modernization (Asset Renewal) Program involves coordinated replacement of end-of-life assets and holistic modernization improvements designed to extend the lives of these substations for the next several decades. The Program takes a holistic, site-by-site approach to facilitating the coordinated and efficient modernization of many aging substations throughout Minnesota Power’s system. In developing the scope for the Haines Road Substation Modernization Project, Minnesota Power is considering the near-term and long-term needs of the area transmission and distribution system as well as the age and condition of existing site infrastructure and modern design standards for safety, accessibility, and maintainability.

Schedule: This project is planned to be in service by the end of 2029.

General Impacts: This project will ensure a continuous and reliable power supply to the Haines Road area in Duluth by replacing old assets prior to failure. At present, it is expected that the impacts will be entirely contained within or adjacent to the existing Haines Road Substation yard, making optimal use of the existing infrastructure to reduce human and environmental impacts.

180 Line Rebuild

MPUC Tracking Number: 2025-NE-N10

Utility: Minnesota Power (MP)

Project Description: Increase rating of Hibbing– Maturi 115 kV Line (180 Line). The project also includes rebuild and reconductor of the transmission line to address age and condition issues.

Need Driver: Post-contingent overloads under higher transfer scenarios and multiple-circuit contingency events, as well as age and condition of existing 180 Line structures and hardware.

Alternatives:

Transmission Alternatives

Reconductor existing line, build new parallel line.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of the transmission system in the area.

Schedule: The project has been delayed to align with other asset renewal and substation modernization projects in the area. Minnesota Power is currently targeting a 2030 in-service date for the project.

General Impacts: The 180 Line Upgrade Project will provide necessary system improvements and asset renewal on Minnesota Power’s 115 kV system without requiring the establishment of additional transmission line corridors. During construction, MP and/or their contractors will be working in the area and will contribute positively to the local economy. No significant traffic impacts are anticipated. The right-of-way will be restored following construction.

Hat Trick Substation Expansion

MPUC Tracking Number: 2025-NE-N11

Utility: Minnesota Power (MP)

Project Description: Expanding the existing Hat Trick 115/23 kV Substation to add a second 115/23 kV transformer and accommodate new 23 kV lines to serve local distribution loads.

Need Driver: The Hat Trick Substation serves Minnesota Power customers in the Eveleth area and south of Virginia. The primary need driver for the Hat Trick Substation Expansion project is establish a more reliable source for distribution customers in and around the City of Eveleth and the surrounding area, and to unload adjacent 115/23 kV substations in anticipation of planned substation modernization projects.

Alternatives:

Transmission Alternatives

Establish a new 115/230 kV substation near Eveleth

Non-Wires Alternatives

Install new distribution-connected generation on the Eveleth area 23 kV system. Non-wire alternatives must be available when needed, dispatchable to support reliable load-serving under contingency conditions, and have an output characteristic sufficient to reduce the effective peak load in the area.

Analysis: The 23 kV system in the Eveleth area is currently by the Hat Trick Substation, with one feeder extending toward Virginia and one feeder extending toward the Laskin and Embarrass Substations in the direction of Hoyt Lakes. Both Virginia and Laskin are scheduled for modernization projects as part of Minnesota Power’s asset renewal program, and the existing 46 kV feeder currently connected to Virginia is planned for conversion to 23 kV. Establishing a redundant transformer and additional 23 kV feeder connections from Hat Trick Substation will improve reliability and resiliency of the local 23 kV system, enhance load-serving capacity for the area between Eveleth and Hoyt Lakes, enable conversion of the non-standard 46 kV feeder to a standard 23 kV operating voltage, and enable reliable construction of the planned modernization projects at the adjacent substations.

Schedule: The project is currently planned to be in service by end of year 2028.

General Impacts: The Hat Trick Substation Expansion Project will ensure a continuous and reliable power supply to Eveleth and the surrounding area. Since the Hat Trick Substation was designed originally to accommodate two distribution transformers, the majority of impacts from the substation modifications will be contained within the existing Hat Trick Substation yard, making optimal use of the existing infrastructure to reduce human and environmental impacts.

Babbitt 115 kV Project

MPUC Tracking Number: 2025-NE-N12

Utility: Minnesota Power (MP)

Project Description: Extend a new 115 kV line from the Mesaba Junction Switching Station to the end of Minnesota Power’s ownership of existing Embarrass – Babbitt 115 kV Line (137 Line), then loop 137 Line into and out of the Babbitt 115 kV Substation by extending new 115 kV line from the Babbitt Tap to the Babbitt Substation. Following establishment of this redundant connection, the existing segment of 137 Line between Embarrass and North Shore Mine will be rebuilt. At the Mesaba Junction Switching Station, a 115 kV line entrance will be constructed, including a circuit breaker and deadend structure, in an existing ring bus position at the substation. At the Babbitt Substation, the 115 kV bus will be expanded to accommodate an additional 115 kV line entrance.

Need Driver: Age and condition of existing 137 Line and redundancy of service to Babbitt-area customers served from 137 Line.

Alternatives:

Transmission Alternatives

Do nothing – ability to maintain the existing 137 Line is severely limited due to outages and doing nothing may lead to structure failures, which is not an acceptable solution.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of the transmission system in the area.

Analysis: The Babbitt 115 kV Project replaces the previously proposed Mesaba Junction 137 Line Project (2021-NE-N14) and 137 Line Rebuild Project (2021-NE-N15), updating and combining the original scope of the two projects into one holistic project. The original Mesaba Junction 137 Line Project became infeasible due to routing constraints in the area, necessitating that the route and scope of the planned improvements in the area be updated. The Babbitt 115 kV Project meets three critical needs for the Babbitt area:

Providing redundancy to an industrial load pocket that requires near-constant availability and to the local Babbitt area that is currently served by a single transmission source
Enabling asset renewal by allowing the existing 137 Line to be rebuilt
Improving reliability with two properly maintained 115 kV transmission sources to the area

With respect to the age and condition concerns on 137 Line, which are the primary drive for the project, rebuilding 137 Line is one of highest priority projects out of many transmission lines across the Minnesota Power system that require age and condition-related upgrades. Many of the original wood pole structures and components on these transmission lines are nearing or beyond the end of their useful lives. As these transmission lines continue to age, the risk of structure and component failures – and therefore the risk of outages, property damage, and safety concerns – will increase. Minnesota Power’s Transmission Line Asset Renewal Program involves identification, prioritization, and coordination of transmission line asset renewal projects to address end-of-life wood poles and other components while holistically considering long-term reliability, capacity, and communications needs. The program is designed to extend the lives of these transmission lines so they can continue to reliably serve Minnesota Power’s customers and the region for many decades to come.

Schedule: This project is currently being re-scoped and is planned to be in service by the end of 2030 with construction anticipated to start in 2027. Minnesota Power anticipates filing a Certificate of Need and Route Permit Application for the project in 2026.

General Impacts: The Babbitt 115 kV Project will preserve and enhance the reliable delivery of power to an important industrial load pocket and to a local area, the Babbitt area, that is currently served by a single transmission source. The project will also provide the opportunity to address significant age and condition and maintenance-related issues on the existing Embarrass – Babbitt 115 kV Line (137 Line). The project is anticipated to require more than 10 miles of new 115 kV transmission in a remote area of northern Minnesota that has been heavily impacted by historical mining operations, making routing of a new corridor challenging. While the project is still in the early stages of routing, it is anticipated that the new transmission line will follow or replace existing transmission line corridors to greatest reasonable extent to minimize establishment of new rights-of-way and to help navigate the varying land use and space constraints throughout the project area. Rebuilding the 137 Line as part of the project will ensure that the existing Embarrass – Babbitt 115 kV Line continues to provide a safe and reliable transmission path for Minnesota Power’s customers. That part of the project also involves replacement of existing assets on the existing transmission line right-of-way, therefore making optimal use of the existing transmission line with little or no additional human or environmental impacts. During construction, MP and/or their contractors will be working in the area and will contribute positively to the local economy. The right-of-way will be restored following construction.

Transmission Line Pole Replacement 2026

MPUC Tracking Number: 2025-NE-N13

Utility: Minnesota Power (MP)

Project Description: This project will replace or modify wood pole transmission structures existing transmission lines across the Minnesota Power footprint. Where possible, C-Trusses will be added to the structures to stabilize minor issues, otherwise full pole or structure replacements are anticipated.

Need Driver: Through routine groundline inspections of the transmission lines, wood pole structures were identified as in need of repair or replacement due to age or condition.

Alternatives:

Transmission Alternatives

There is no more economical or less impactful solution than replacing the existing wood poles on the existingtransmission lines.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of the transmission system in the area.

Analysis: Across Minnesota Power’s system there are many transmission lines that require age and condition-related upgrades. Many of the original wood pole structures and components on these transmission lines are nearing or beyond the end of their useful lives. As these transmission lines continue to age, the risk of structure and component failures – and therefore the risk of outages, property damage, and safety concerns – will increase. Minnesota Power’s Transmission Line Asset Renewal Program involves identification, prioritization, and coordination of transmission line asset renewal projects to address end-of-life wood poles and other components while holistically considering long-term reliability, capacity, and communications needs. The program is designed to extend the lives of these transmission lines so they can continue to reliably serve Minnesota Power’s customers and the region for many decades to come. In developing the pole replacement program, Minnesota Power has taken into consideration the condition of wood poles based on field surveys, as well as the near-term and long-term needs for the transmission lines involved, targeting the highest-priority pole replacements for continued safe and reliable operation of the transmission lines.

Schedule: This project is targeted for completion by the end of the year 2026.

Transmission Line Pole Replacement 2027

MPUC Tracking Number: 2025-NE-N14

Utility: Minnesota Power (MP)

Need Driver: Through routine groundline inspections of the transmission lines, wood pole structures were identified as in need of repair or replacement due to age or condition.

Alternatives:

Transmission Alternatives

There is no more economical or less impactful solution than replacing the existing wood poles on the existing transmission lines.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of the transmission system in the area.

Analysis: Across Minnesota Power’s system there are many transmission lines that require age and condition-related upgrades. Many of the original wood pole structures and components on these transmission lines are nearing or beyond the end of their useful lives. As these transmission lines continue to age, the risk of structure and component failures – and therefore the risk of outages, property damage, and safety concerns – will increase. Minnesota Power’s Transmission Line Asset Renewal Program involves identification, prioritization, and coordination of transmission line asset renewal projects to address end-of-life wood poles and other components while holistically considering long-term reliability, capacity, and communications needs. The program is designed to extend the lives of these transmission lines so they can continue to reliably serve Minnesota Power’s customers and the region for many decades to come. In developing the pole replacement program, Minnesota Power has taken into consideration the condition of wood poles based on field surveys, as well as the near-term and long-term needs for the transmission lines involved, targeting the highest-priority pole replacements for continued safe and reliable operation of the transmission lines.

Schedule: This project is targeted for completion by the end of the year 2027.

Brainerd Capacitor Bank Replacement

MPUC Tracking Number: 2025-NE-N15

Utility: Minnesota Power (MP)
Project Description: The 115 kV capacitor bank located on the Brainerd 115 kV bus will be replaced with a new standard-sized capacitor bank.

Need Driver: The capacitor bank located on the Brainerd 115 kV Substation is over 50 years old, has been progressively failing. Additionally, the capacitor bank is of a type and size that is no longer a standard for Minnesota Power. Because of the age and condition of the capacitor bank, it needs to be replaced in order to maintain reliable transmission voltage support.

Alternatives:

Transmission Alternatives

There are no transmission alternatives to replacing the aging and non-MP standard assets at the existing Brainerd 115 kV Substation.

Non-Wires Alternatives

Non-wire alternatives are not viable because they cannot address concerns related to age and condition of the transmission assets in the area.

Schedule: This project is planned to be in service by the end of the year 2027.

General Impacts: This project will replace aging transmission assets to ensure continuous and reliable voltage support. The impacts of the project will be entirely contained within the existing Brainerd Substation yard, making optimal use of the existing infrastructure to reduce human and environmental impacts.

Riverton to Mud Lake Temperature Upgrade Project

MPUC Tracking Number: 2025-NE-N16

Utility: Great River Energy (GRE)

Project Description: This project will raise the operating temperature of the line from 195 °F to 212 °F maximizing the full conductor rating of the transmission line via pole replacements.

Need Driver: The Riverton to Mud Lake transmission line facilitates bulk electric transfers. Raising the operating temperature of this line is needed to increase current carrying capacity of the transmission line, resulting in less congestion seen on the system.

Alternatives:

Transmission Alternatives

No transmission alternatives were considered since upgrading the temperature rating of an existing transmission line requires the least amount of transmission construction to take place.

Non-Wires Alternatives

The Riverton – Mud Lake 230 kV line is part of the Bulk Electric System (BES) and is needed to facilitate large power transfers through the region and can’t be replaced by a non-wires alternative.

Analysis: Looking at a three-year window of time (2022 – 2024), the Mud Lake – Riverton ‘MR’ 230 kV line is causing congestion for 194 hours. For the same time period, the Benton County – Mud Lake ‘MR’ 230 kV line is causing congestion for 373 hours. Collectively, the Riverton-Mud Lake-Benton County path binds 567 hours. Very small changes in conditions can shift which segment binds first, masking the other. Therefore, it is practical to consider the congestion on this path collectively. This project upgrade is the most cost-effective way to add capacity and alleviate congestion.

Schedule: The project is planned to be in service by 2029.

General Impacts: This project will replace existing structures on existing right-of-way and will have almost no impact. The right-of-way will be restored following construction. No new landowners will be impacted by construction. No significant traffic impacts are anticipated.

LCP Peary Substation Rebuild

MPUC Tracking Number: 2025-NE-N17

Utility: Great River Energy (GRE)

Project Description: This project plans to rebuild the Peary substation by building a new Peary substation adjacent to the existing Peary substation.

Need Driver: The Peary substation is nearing the end of its useful life and needs to be rebuilt to continue serving reliable power.

Alternatives:

Transmission Alternatives

No transmission alternatives were considered due to Lake Country Power’s need to retain a load serving point at the Peary interconnection.

Non-Wires Alternatives

Non-wires alternatives were not considered as it isn’t feasible for the Peary load serving substation to be replaced by a non-wires solutions.

Analysis: The Peary rebuild project will replace old equipment to strengthen reliability to the Eveleth area loads served by Lake Country Power.

Schedule: The project is planned to be in service by October 2027.

General Impacts: The Peary rebuild will take place adjacent to the existing Peary substation. No new landowners will be impacted by construction. No significant traffic impacts are anticipated.

Iona 115 kV Conversion Project

MPUC Tracking Number: 2025-NE-N18

Utility: Great River Energy (GRE)

Project Description: This project will build a 0.5-mile, 115 kV tap line to interconnect the Iona substation to the 47 Line.

Need Driver: This project is needed to provide reliable electric service to the Iona Distribution Substation. The Iona Distribution Substation is currently served by a 34.5 kV system with approximately 3.5 miles of radial exposure. This 34.5kV system has poor reliability record and is inadequate for supporting dependable service. A nearby 115 kV transmission system, located just half a mile from the substation, offers superior reliability and greater capacity, making it a more suitable source to meet current service demands and support future economic development in the area.

Alternatives:

Transmission Alternatives

Upgrading the Iona Distribution Substation to connect with the nearby 115 kV transmission line was determined to be the most viable solution. The only alternative, continuing service from the existing 34.5 kV radial system, was not pursued further due to its poor reliability and limited capacity. No additional transmission alternatives were considered.

Non-Wires Alternatives

This project is focused on improving electric service reliability to the Iona Distribution Substation by interconnecting it to a nearby 115 kV transmission line. Because the project involves establishing a direct transmission connection to an existing delivery point, non- wires alternatives are not viable options.

Analysis: The Iona Distribution Substation upgrade project addresses a critical reliability issue stemming from its current service from the 34.5 kV system. The proposed solution, interconnecting the substation to a nearby 115 kV transmission line offers a substantial improvement in reliability and capacity in comparison to the 34.5 kV system.

Schedule: The project is planned to be in service by 2028.

General Impacts: The Iona project requires approximately 0.5 miles of new 115 kV high voltage transmission following County Road 84. The Project is located in predominantly agricultural lands. Prior to construction, GRE will acquire the necessary right-of-way and permits for construction of the Project. The preliminary design follows existing road rights-of-way in order to minimize impacts to nearby residents and environmental features. Prior to construction, GRE will complete a desktop review of environmental features that may be present in the right of way and will work with the appropriate permitting agencies, as required, to minimize impacts during construction. No significant traffic impacts are anticipated. The right-of-way will be restored following construction.

Heartland Lakes 115 kV Project

MPUC Tracking Number: 2025-NE-N19

Utility: Great River Energy (GRE)

Project Description: This project will build a new, 4.3-mile, 115 kV tap line to interconnect the Heartland Lakes substation which will be served by a breakered position from the Hubbard 115 kV bus.

Need Driver: The Heartland Lakes 115 kV Project is needed to unload Osage, Potato Lake, and RDO distribution substation and provide redundancy to the area, expanding backfeeding capability between substations. This project will serve growing load in the area and provide reliability and operational flexibility.

Alternatives:

Transmission Alternatives

Transmission alternatives were not considered for this project, as they would not address the core need for establishing an additional delivery point to serve growing load in the area. While this need cannot be achieved through alternative transmission configurations, alternative routing options for the interconnecting transmission line will be evaluated as part of the permitting process.

Non-Wires Alternatives

A new distribution substation is needed to reliably serve growing loads and to establish redundancy through sufficient backfeed capabilities. These needs cannot be met through non-wires alternatives. Therefore, non-wires options were not considered further for this project.

Analysis: Heartland Lakes will pick up load from the Osage, Potato Lake, and RDO load serving substations to alleviate transformer loading and provide a redundant source. The Heartland Lakes substation will help with forecasted load growth in the area and allow for better operational flexibility. This is a cost-effective way to provide more capacity and redundancy to the distribution system in this area.

Schedule: The project is planned to be in service by winter 2029.

General Impacts: The Heartland Lakes project requires approximately 4.3 miles of new 115 kV high voltage transmission following 129th Ave. The Project is located in predominantly agricultural lands. Prior to construction, GRE will acquire the necessary right-of-way and permits for construction of the Project. The preliminary design follows existing road rights-of-way in order to minimize impacts to nearby residents and environmental features. Prior to construction, GRE will complete a desktop review of environmental features that may be present in the right of way and will work with the appropriate permitting agencies, as required, to minimize impacts during construction. No significant traffic impacts are anticipated. The right-of-way will be restored following construction.

Boulder Lake 115 kV Project

MPUC Tracking Number: 2025-NE-N20 Utility: Great River Energy (GRE) Project Description:
This project will build a 4.7-mile, 115 kV tap line to interconnect the Boulder Lake substation.
Need Driver: This project is needed to alleviate transformer loading at Itasca-Mantrap’s Nevis, Long Lake, and Mantrap distribution substations. By establishing a new distribution substation, the project will support reliable service for growing load demands and enhance operational flexibility in the area.

Alternatives:

Transmission Alternatives

Transmission alternatives were not considered for this project as they would not address the core need for establishing an additional delivery point to serve growing load in the area. While this need cannot be achieved through alternative transmission configurations, alternative routing options for the interconnecting transmission line will be evaluated as part of the permitting process.

Non-Wires Alternatives

A new distribution substation is needed to reliably serve growing loads in the area. This need cannot be met through non-wires alternatives. Therefore, non-wires options were not considered further for this project.

Analysis: The Boulder Lake substation will help with forecasted load growth in the area and allow for better operational flexibility.

Schedule: The project is planned to be in service by 2030.

General Impacts: The Boulder Lake project requires approximately 4.8 miles of new 115 kV high voltage transmission following 209th Ave, 200th street, and 219th Ave. The Project is located in predominantly agricultural lands. Prior to construction, GRE will acquire the necessary right- of-way and permits for construction of the Project. The preliminary design follows existing road rights-of-way in order to minimize impacts to nearby residents and environmental features. Prior to construction, GRE will complete a desktop review of environmental features that may be present in the right-of-way and will work with the appropriate permitting agencies, as required, to minimize impacts during construction. No significant traffic impacts are anticipated. The right- of-way will be restored following construction.

Pillsbury Area Projects

MPUC Tracking Number: 2025-NE-N21

Utility: Great River Energy (GRE)

Project Description: The Pillsbury Project will build a 2.0-mile, 115 kV tap line to interconnect the existing Stearns Electric Association (SEA) Pillsbury distribution substation to the MP-owned 41 Line.

Need Driver: SEA plans to rebuild the Pillsbury Distribution Substation as an end-of-life replacement. While the primary goal is to address aging infrastructure and condition concerns, the project also presents an opportunity to enhance service reliability by upgrading from 34.5kV to 115kV. Transitioning to the 115kV system will support long-term reliable service, improve operational resilience, and provide capacity for future growth at the Pillsbury Distribution Substation

Alternatives:

Transmission Alternatives

Upgrading the Pillsbury Distribution Substation to connect with the nearby 115 kV transmission line was identified as the most reliable solution. The only other option, continuing service via the existing 34.5 kV system was dismissed due to its limited capacity and need for improved reliability at Pillsbury. Given these constraints, no additional transmission alternatives were evaluated. However, alternative routing options for the new 115 kV transmission line will be explored during the routing and permitting phase of the project.

Non-Wires Alternatives

This project aims to enhance electric service reliability at the Pillsbury Distribution Substation by transitioning from the existing 34.5 kV interconnection to a nearby 115 kV transmission line. Since the project involves interconnecting a rebuilt distribution substation, non-wires alternatives were considered unsuitable and not pursued further.

Analysis: The Pillsbury Substation is one of SEA’s distribution substations currently served by the 34.5 kV transmission system, which generally offers lower capacity and reliability compared to the 115 kV system. As the substation reaches the end of its service life, its replacement presents a strategic opportunity to enhance reliability and support future growth. Upgrading the substation to 115 kV standards and interconnecting it with a nearby 115 kV transmission line will significantly improve service performance and position the substation to effectively support economic development in the area for the long term.

Schedule: The project is planned to be in service by fall of 2027.

General Impacts: The Pillsbury project requires approximately 2.0 miles of new 115 kV high voltage transmission following County Road 105. The Project is located in predominantly agricultural lands. Prior to construction, GRE will acquire the necessary right-of-way and permits for construction of the Project. The preliminary design follows existing road rights-of-way in order to minimize impacts to nearby residents and environmental features. Prior to construction, GRE will complete a desktop review of environmental features that may be present in the right- of-way and will work with the appropriate permitting agencies, as required, to minimize impacts during construction. No significant traffic impacts are anticipated. The right-of-way will be restored following construction.

6.4.2 Completed Projects

The table below identifies those projects by Tracking Number in the Northeast Zone that were listed as ongoing projects in the 2023 Biennial Report but have been completed or withdrawn since the 2023 Report was filed with the Minnesota Public Utilities Commission in November 2023. Information about each of the completed projects is summarized briefly in the table below. More information about these projects and inadequacies can be found in earlier reports. Projects that were listed as being complete in the 2023 Report are not repeated here, but more information about those projects can be found in these earlier reports.

MPUC Tracking Number	Description	MPUC Docket	Utility	Date Completed
2019-NE-N15	Portage Lake 115/69 kV Project	N/A	GRE	Completed in 2024
2021-NE-N11	Two Islands 115 kV Project	N/A	GRE	Completed in 2024
2021-NE-N27	Riverton - Wing River Storm Structures	N/A	GRE	Completed in 2024
2015-NE-N2	Iron Range – Arrowhead 345 kV Line	N/A	MP	Withdrawn: Original project from 2014 replaced by Iron Range – St Louis County – Arrowhead 345 kV Project (2025-NE-N2)
2017-NE-N3	Little Falls Substation Modernization	N/A	MP	Withdrawn
2019-NE-N6	Long Prairie Substation Modernization	N/A	MP	Completed in 2023
2019-NE-N10	Babbitt Area 115 kV Project	N/A	MP	Withdrawn: Replaced by Babbitt 115 kV Project (2025-NE-N13)
2021-NE-N1	HVDC Line Hardening	N/A	MP	First Phase Completed in 2024 Subsequent Phases Placed on Hold Indefinitely
2021-NE-N6	15th Ave West 115/34kV Transformer	N/A	MP	Completed in 2024
2021-NE-N8	LSPI Cap Bank Asset Renewal	N/A	MP	Completed in 2024
2021-NE-N9	Canosia Road Substation 34 kV Expansion	N/A	MP	Completed in 2023
2021-NE-N14	Mesaba Junction 137 Line Extension	N/A	MP	Withdrawn: Replaced by Babbitt 115 kV Project (2025-NE-N13)
2021-NE-N15	137 Line Rebuild	N/A	MP	Withdrawn: Replaced by Babbitt 115 kV Project (2025-NE-N13)
2021-NE-N20	105 & 106 Line Upgrade	N/A	MP	Completed in 2024
2021-NE-N22	126 Line Asset Renewal	N/A	MP	Completed in 2024
2023-NE-N2	40 Line Rebuild	N/A	MP	Completed in 2024
2023-NE-N3	Brainerd Crypto	N/A	MP	Withdrawn

6.4 Northeast Zone

6.4.1 Needed Projects

Duluth 230 kV Project

Alternatives:

HVDC Modernization Project

Alternatives:

HVDC 900 MW Transmission Line Upgrades

Alternatives:

25 Line Rebuild

Alternatives:

Badoura 230/115 kV Transformer Replacement

Alternatives:

Duluth Loop Reliability Project

National Breaker Replacements

Alternatives:

Hibbing Substation Modernization

Alternatives:

Verndale Substation Modernization

MPUC Tracking Number: 2021-NE-N4

Alternatives:

Badoura 115 kV Substation Modernization

Alternatives:

Forbes 230 kV Modernization

Alternatives:

Cloquet Substation Modernization

Alternatives:

Boswell 115/23 kV Transformer Addition

Alternatives:

56 Line Upgrade

Alternatives:

Riverton 230 kV STATCOM

Alternatives:

13 Line Rebuild

Northland Reliability Project

Alternatives:

Maturi Substation Expansion

Alternatives:

Mahtowa Substation Expansion

MPUC Tracking Number: 2023-NE-N5

Alternatives:

158 Line Rebuild

Arrowhead 115 kV Single Point of Failure

Alternatives:

Forbes 115 kV Single Point of Failure

Alternatives:

Ridgeview 115/34 kV Transformer Addition

Alternatives:

Wrenshall Substation Modernization

133 Line Rebuild

Alternatives:

Maple River – Cuyuna 345 kV Project

Alternatives:

Iron Range – St. Louis County – Arrowhead 345 kV Project

Alternatives:

24 Line Rebuild

Alternatives:

Arrowhead 230 kV EEE Replacement

Alternatives:

Transmission Line Pole Replacement 2025

Alternatives:

Iron Range 500 kV Reactor Addition

Alternatives:

Shannon Capacitor Bank Replacement

Alternatives:

26 Line Rebuild

Alternatives:

Haines Road Substation Modernization

Alternatives:

180 Line Rebuild

Alternatives:

Hat Trick Substation Expansion

Alternatives:

Babbitt 115 kV Project

Alternatives:

Transmission Line Pole Replacement 2026

Transmission Line Pole Replacement 2027

Brainerd Capacitor Bank Replacement

Riverton to Mud Lake Temperature Upgrade Project

LCP Peary Substation Rebuild

Iona 115 kV Conversion Project