$1 Billion Upgrade for Minnesota Power's Square Butte HVDC Transmission Line

Minnesota Power has announced plans to upgrade its HVDC transmission system “Square Butte”, a move that has garnered recognition from federal and state partners. The line stretches 460 miles from North Dakota to Duluth, serving customers in North eastern Minnesota.

Originally commissioned almost 50 years ago, the modernization project will upgrade the HVDC converter stations to modern MMC VSC technology, and upgrade the capacity of the line from 500 to 900 MW.

With an investment of almost $1 Billion the upgrade will allow for near-doubling the capacity of the existing line, enabling it to serve more customers and handle greater load. The upgraded system will have the capability to flow energy in both directions, improving overall system resilience.

Josh Skelton, ALLETE Vice President and Chief Operating Officer at Minnesota Power, emphasized the benefits of the new technology, stating that it will significantly improve the line's efficiency and capacity while using the same physical infrastructure.

David Crane, Under Secretary for Infrastructure at the United States Department of Energy, highlighted the importance of maintaining affordability and reliability while de-carbonising the system. He noted that the utility already operates with high reliability, and the challenge is to maintain this standard while transitioning to cleaner energy sources.

The project has received partial funding approval, with additional approvals pending. This upgrade represents a significant step in modernizing critical energy infrastructure while supporting the transition to more sustainable power generation and distribution.

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