Minnesota Power has broken ground on the North Dakota portion of a more than $450 million project to modernize its high-voltage direct-current (HVDC) transmission system.

The Aug. 19 groundbreaking took place at the converter station upgrade site near Center, North Dakota, where construction is underway on a new facility that will replace transmission infrastructure that is nearly 50 years old.

The converter station is part of Minnesota Power’s 465-mile HVDC line, which began operating in 1977. The line is one of five overhead HVDC lines in the United States, according to Minnesota Power.

The modernization project will replace key equipment dating to the 1970s and add flexibility to the transmission system, according to the utility.

“One of the most important benefits of this modernization is flexibility,” said Josh Skelton, chief operating officer for Minnesota Power. “When extreme weather hits, when system conditions change quickly, or when energy is needed in a different place than expected, the ability to move power both ways on this line becomes a real advantage.”

The converter station near Center, along with a similar facility in Hermantown, Minnesota, converts alternating current electricity into direct current for long-distance transmission and can convert direct current back into alternating current when electricity is delivered to where it is needed.

Minnesota Power began planning the modernization more than 10 years ago after identifying the need to replace key equipment. The North Dakota Public Service Commission approved permits for the project in 2025 following study, planning and review.

Siemens Energy is supplying the HVDC technology for the project.

“With this groundbreaking, North Dakota is becoming home to a high-tech modernization project that combines our proven HVDC experience with the next generation of converter station technology,” said Hauke Juergensen, senior vice president of Grid Solutions for Siemens Energy. “By building with future expansion in mind, North Dakota will have a reliable, long-term energy solution that can support economic growth and increasing demand for years to come.”

HVDC technology can lose 15% to 30% less energy over long distances than a comparable alternating-current line, according to Minnesota Power.

Mortenson is the project’s general contractor and is working with Minnesota Power to emphasize local labor and regional economic activity during construction.

“North Dakota is an energy leader, and its workers and contractors will play an important role in building this project,” said Jake Frazier, Mortenson vice president and general manager of Power Delivery. “We’re proud to partner on an investment that supports local labor, creates good jobs and brings lasting economic benefits to the region.”

The project represents about a $450 million investment in North Dakota, according to Minnesota Power. The utility said construction will support skilled trades and local businesses while adding to the property tax base of communities hosting the infrastructure.

Claire Vigesaa, executive director of the North Dakota Transmission Authority, said the organization appreciates Minnesota Power’s continued investment in the state’s infrastructure.

“This project is providing a superhighway for North Dakota’s generation and two-way flow options to enhance grid reliability and transmission efficiency,” Vigesaa said.

Minnesota Power and ALLETE have operated in North Dakota for more than 50 years, including through ownership of BNI Coal and investments in generation, fuel supply, transmission and wind energy.

The utility said it has worked with local landowners, public officials and community partners throughout the project’s planning process.