South Central/Southwest Wisconsin and North Central Illinois
Zone 3
Transmission system characteristics in Zone 3
ATC delivers power in Zone 3 with various transmission facilities including:
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Columbia-North Madison 345‑kV lines,
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Columbia-Rockdale 345‑kV line,
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Paddock-Rockdale 345‑kV line,
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Paddock-Wempletown 345‑kV line,
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Rockdale-Wempletown 345‑kV line
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Rockdale-Cardinal 345-kV line, which was energized in early 2013, and
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138‑kV facilities from the Nelson Dewey Power Plant, around the Madison area, and in the northwest and southeast portions of Zone 3.
Transmission system performance issues in Zone 3 include limited import capability, overloaded lines and equipment, high and low system voltages. The causes of these emerging issues include steady growth in certain areas, new power plants, power plant retirement and different generation dispatch scenarios.
Transmission system limitations in Zone 3
In our analysis of Zone 3, we identified low voltages, high voltages and transmission-facility overloads. Low voltages are located in the Verona, Beloit, Hustisford and Waunakee areas. Several overloads on 138 kV and 69 kV facilities in Zone 3 are emerging concerns.
Electric system overview
Increases expected in population, employment – Population in Zone 3 is projected to grow about 0.9 percent annually between now and 2022, and employment is projected to grow about 1.2 percent each year for the same time period. Dane County is projected to realize the largest increase in population and employment.
Electricity usage growing – Electric load is expected to grow approximately 1.12 percent annually through 2022 for all of Zone 3.
Transmission projects in Zone 3
We have implemented four network projects in Zone 3 since the 2012 Assessment, most notably the Rockdale – Cardinal 345-kV line project and the Nine Springs/Pflaum area line uprate and capacitor bank project.
Our current plans in Zone 3 include 31 system reliability and economic projects between 2013 and 2027, 15 of which are driven by our new Study-Based Rating Methodology. These projects are in various stages of development. The most notable planned, proposed, provisional and asset renewal projects in Zone 3, along with their projected year of completion and the factors driving the need for the projects, are listed below.
Zone 3 includes the counties of:
- Columbia , WI
- Crawford (S) , WI
- Dane , WI
- Dodge , WI
- Grant , WI
- Green , WI
- Iowa , WI
- Jefferson , WI
- Lafayette , WI
- Richland , WI
- Rock , WI
- Sauk , WI
- Walsworth , WI
- Winnebago (N) , IL
Zone 3 Proposed Projects
| Project Description | In-service year | Need driver |
|---|---|---|
| Sun Valley Tap-Oregon 69‑kV line rebuild | 2016 | Overloads and improve line condition and area voltages |
| Badger Coulee: La Crosse area-North Madison-Cardinal | 2018 | Reliability, economics and public policy |
| Spring Valley-North Lake Geneva 138‑kV line construction | 2019 | Overloads and low voltages, provide network service |
| Cardinal Bluffs: Dubuque County area-Cardinal 345-kV line construction | 2020 | Reliability, economics and public policy |
Zone 3 Provisional Projects
| Project Description | In-service year | Need driver |
|---|---|---|
| Colley Road-Brick Church 69‑kV line rebuild | 2018 | Overloads and low voltages |
| Cardinal-Blount 138‑kV line construction | 2024 | Overloads and low voltages |
| West Middleton-Pheasant Branch 69‑kV line rebuild | 2025 | Overloads and low voltages |
Zone 3 Asset Renewal Projects
| Project Description | In-service year | Need driver |
|---|---|---|
| Doylestown-Rio Pumping Station 69‑kV line rebuild | 2013 | Condition and performance |
| Dam Heights-Portage 69‑kV line rebuild | 2016 | Condition and performance |
| Concord-Rubicon-Butler Ridge-Hartford 138‑kV line rebuild | 2016 | Condition and performance |
| Belmont-Rewey 69‑kV line rebuild | 2018 | Condition and performance |
| Boscobel-Lone Rock 69‑kV line rebuild | 2018 | Condition and performance |
| West Middleton-Stagecoach 69‑kV underground cable replacement | 2019 | Condition and performance |
| South Beaver Dam-Horicon 69-kV line rebuild | 2020 | Condition and performance |