ATC completes HV transmission line

Paddock-Rockdale 345-kV Transmission Line expands Wisconsin-Illinois intertie capacity, alleviates congestion, enhances grid reliability, and enables wholesale electricity market access for lower-cost imports and renewable energy integration across MISO, using existing right-of-way.

American Transmission Co. has put into service a new, 35-mile high-voltage electric transmission line in south central Wisconsin that provides local electric utilities with improved access to the regional energy market to buy and sell electricity when it is economic to do so.

The 345-kilovolt circuit was built on an existing transmission line right-of-way between the Rockdale Substation in the Town of Christiana in Dane County and the Paddock Substation located in the Town of Beloit in Rock County. The lines that extend south out of the Paddock Substation into Illinois create a path for importing power into Wisconsin.

“Completion of this project is a significant milestone,” said Flora Flygt, director of Transmission Planning. Paddock-Rockdale is the first transmission line project within the footprint of the Midwest Independent System Operator that was justified on economics, a shift reflected in recent approvals across Wisconsin. Until this project, transmission lines in the region have almost exclusively been built to enhance reliability of electric power in the area. Although improved reliability will be a by-product of the project, economics drove the decision to build.

Flygt said, “The primary benefit of this line is local electric distribution companies now have greater ability to participate in the wholesale electricity market.” She explains, “Wisconsin has fewer transmission line connections to other states compared with its neighboring states, and proposals for the Madison area power lines highlight ongoing capacity needs in the region. This transmission congestion limits the ability of electric utilities to access the market to purchase lower-cost electricity when prices are lower and sell into the market when prices are higher. The economic benefits of enhanced access can be passed on to end-use customers. The Paddock-Rockdale project provides the needed transmission capacity for today’s energy marketplace, especially with the growing movement toward renewable energy.”

The Paddock-Rockdale project was completed ahead of schedule, and within the approved $133 million budget. Anticipated savings from the project are expected to more than pay for its development.

During construction of the line, ATC took careful consideration of the cost and the environment, using a helicopter for a portion of the work to expedite stringing wire and installing components, as also used in the western Kenosha County rebuild by ATC during similar projects. By accessing the line via helicopter, fewer timber mats were placed as temporary roads for construction equipment on the ground. As a result, soil disturbance was minimized, which makes restoration work following completion of construction easier and less costly. Restoration will continue throughout the spring and summer.

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