New transmission lines are the best solution to the future electrical needs of the Wauwatosa, Wis., area, according to a study by American Transmission Company (ATC) and We Energies.
Of four solutions studied in 2010, including a distribution solution of a substation transformer addition (Alternative I), and a hybrid solution of a new recycling center substation (Alternative II), the companies determined that new transmission lines (Alternatives III and IV) would best meet load growth and other needs, according to a March 28 filing with the Wisconsin Public Service Commission.
“While Alternative I satisfied the immediate load growth needs, within five years of the requested in-service date, the added distribution capacity would be exhausted and a transmission source similar to Alternative III or IV would be required,” they said in the study. Those alternatives would require construction of approximately 1.7 miles to 2.0 miles of new 138-kV transmission line.
Alternative III includes a connection to one of two double circuit 138-kV lines, strung on lattice towers with four circuit positions, three of which are currently occupied, and Alternative IV includes an interconnection choice of multiple transmission lines around 96th Street Substation.
The total cost estimates for the two alternatives range from $20.7m to $22.3m million, depending on selected route and line configuration, the companies said. The project has a proposed April 1, 2015 in-service date.
If placed underground, the cost estimates for the projects would increase to $35.6m to $37.1m in 2014 dollars, the companies said.
The project is intended to serve the needs of We Energies’ forecasted 13.2-kV load growth as given in the Load Interconnection Request Form (LIRF) for the Milwaukee County Regional Medical Center (MRMC).
We Energies in 2009 submitted an LIRF #4122 for a new transmission to distribution interconnection known as the New Milwaukee County 138/13.2-kV Substation, to accommodate both forecast and non-forecast load growth on their distribution system in the Wauwatosa area. The proposed substation would be located near the MRMC, along 92nd Street and Watertown Plank Road in Wauwatosa. The existing Milwaukee County, 24.9/13.2-kV substation serves the MRMC area load, which was approximately 17.4 MVA in 2008, and is connected to We Energies’ 96th Street Substation. The MRMC load is projected to be 41.9 MVA by 2021.
The companies projected that by 2015, increasing load would result in the existing Milwaukee County 24.9/13.2 kV substation to be loaded to 113% of its contingency rating. The 24.9-kV alternate source feeder from the 96th Street Substation to Milwaukee County 24.9/13.2 kV substation would be loaded to 130% in 2015, the companies said.
ATC and We Energies noted that other potential load growth on We Energies’ 24.9-kV distribution system may occur, including Milwaukee County Grounds expansion, new and existing customers in Research Park, new hotels, and the Milwaukee County Grounds, which includes the proposed UWM Innovation Park as well as the Milwaukee County Power Plant, which is also forecasting increased loads.
The MRMC load growth and provisions for anticipated future loads served by both the 13.2 kV and 24.9 kV distribution systems are the key drivers for the project, according to the study. Shifting 13.2 kV load from the 24.9 kV distribution system to a new 138 kV source, creates additional 24.9 kV distribution system capacity.
The determination of an underground or overhead solution will be made via the routing and siting, public outreach, and regulatory processes.
We Energies is a subsidiary of Wisconsin Energy Corp. (NYSE:WEC).