Wisconsin Public Service Commission Reviews American Transmission Company's Central Wisconsin Transmission Line Project

Strategic Insights -

The Public Service Commission of Wisconsin has provided an update on its review of the American Transmission Company LLC (ATC) and Northern States Power Company-Wisconsin (NSPW) application for the Grid Forward - Central Wisconsin Transmission Line Project. The proposed project, part of the Midcontinent Independent System Operator's (MISO) Long Range Transmission Planning (LRTP) Tranche 1, aims to integrate more low-cost renewable resources into the transmission system, reduce congestion, and produce fuel cost savings. The project involves the construction of a new 345 kilovolt (kV) high voltage transmission line connecting the Tremval Substation to the Arpin Substation and terminating at the Columbia Substation.

Key Takeaways:

  • The proposed project is part of MISO's LRTP Tranche 1, aiming to reduce congestion and produce fuel cost savings by integrating more low-cost renewable resources.
  • The project involves the construction of a new 345 kV high voltage transmission line, approximately 200 miles long, with estimated costs between $1.596 billion and $1.630 billion.
  • The proposed project will use self-supporting tubular steel monopole structures with several structure types and configurations, accommodating different angles, dead-end structures, and terrain.
  • Commission staff reviewed the applicants' PowerWorld modeling analysis, verifying the results and concluding that the proposed project will improve reliability and resiliency of the regional transmission system.
  • The project includes the expansion of the Arpin Substation for a new 345 kV yard, the addition of an additional 345 kV position at the Columbia Substation, and modifications at several other substations.
  • The proposed project will have a total contingency reserve representing approximately 15 percent of the cost estimate.

Statistics:

  • Estimated project cost: $1.596 billion - $1.630 billion
  • Length of the proposed transmission line: approximately 200 miles
  • PowerWorld modeling analysis: verified and concluded that the proposed project will improve reliability and resiliency
  • Number of substations to be modified: several
  • Total contingency reserve: approximately 15% of the cost estimate

Sources:

  • [Public Service Commission of Wisconsin Direct Testimony of Bert Chee, Division of Energy Regulation and Analysis, American Transmission Company LLC, and Northern States Power Company-Wisconsin, Docket 5-CE-157, July 10, 2025]
  • [https://apps.psc.wi.gov/]