American Transmission Co. projects

Project website for a Wisconsin-based company that owns and operates the high-voltage electric transmission system that powers communities in portions of the Upper Midwest.

Mackinac HVDC Flow-Control Project

Project overview
ATC is installing a high-voltage, direct current flow-control device and building the new Mackinac Substation near St.Ignace, Mich., to better manage power flows into and out of the Upper Peninsula.

Despite significant upgrades to transmission infrastructure in the Upper Peninsula in recent years, operational challenges remain due to the delicate balance that exists between generation, load, market flows and transmission. ATC operators face challenges balancing the real-time reliability of the system and the need for outages to allow maintenance work to assure long-term performance.

The innovative, HVDC project will allow the flows between Upper and Lower Michigan to be controlled by MISO, maintaining appropriate thermal and voltage levels on the system. Approved by the MISO board of directors in June 2011, the project is eligible for cost-sharing as a baseline reliability project.

Project description
The station will use HVDC Light technology, designed by ABB, a leading international power and automation technology group. ABB will design and install the 200-megawatt station with two converters. In a back-to-back system, the two converters are connected directly to each other, without a DC transmission line, making it possible to fully control the power transfer through the connection.

The equipment will be housed in a tall control building with a footprint of about 280 feet by 110 feet.

The cost of the project is estimated to be $130 million, which is a less-expensive and faster solution compared to the portfolio of transmission lines studied as alternatives.

Project at a Glance
Location:Straits Substation, St. Ignace, Mich.
Voltage:138 kilovolts
Cost:$130 million
Status of project:Complete
Obtain local permits:As necessary
Construction start:Late spring 2012
In-service date:2014
*Dates are anticipated and subject to changes