South Central/Southwest Wisconsin and North Central Illinois
Zone 3
Transmission system limitations in Zone 3
In our analysis of Zone 3, we identified transmission facility overloads between Portage and Columbia substations. These overloads are the result of load modifications in the Portage area.
In addition, other emerging issues resulting in potential facility overloads could include steady growth in certain areas and different generation dispatches. The most severe limitations are expected to occur during both peak and off‑peak periods.
Electric system overview
Increases expected in population, employment – Population in Zone 3 is projected to grow about 0.6 percent annually between now and 2028, and employment is projected to grow about 1.1 percent each year for the same time period. Dane County is projected to realize the largest total increase in population and employment. Dane County is also projected to have the highest annual growth rates in population and employment at 0.9% and 1.4%, respectively.
Electricity usage growing
Electric load is forecasted to grow approximately 0.7% annually through 2029 in Zone 3.
Transmission projects in Zone 3
The most notable planned, proposed, and provisional network projects 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
- Walworth , WI
- Winnebago (N) , IL
Zone 3 Planned Projects
| Project Description | Project # | In-service year | Need driver |
|---|---|---|---|
| Boscobel–Lone Rock 69-kV (Y-124), rebuild | 1 | 2019 | Condition and performance |
| Spring Valley–North Lake Geneva 138‑kV line | 2 | 2019 | T‑D interconnection and reliability |
| Portage–Staff–North Randolph 138-kV lines (X-6) (X-98), rebuild | 3 | 2020 | Condition and performance |
| Sheepskin–Stoughton 69-kV (Y-12), rebuild | 4 | 2021 | Condition and performance |
| Cardinal SS–Hickory Creek SS 345-kV, line construction | 5 | 2023 | Reliability, economic and policy |
Zone 3 Proposed Projects
| Project Description | Project # | In-service year | Need driver |
|---|---|---|---|
| J870/J871 GIC Highland, generator interconnection facilities and network upgrades | 6 | 2020 | G‑T interconnection |
| J584 GIC Jordan SS, generator interconnection facilities and network upgrades information | 7 | 2021 | G‑T interconnection |
| Northern Lights Substation, new T-D interconnection | 8 | 2021 | T‑D interconnection |
| Portage SS–Columbia SS 138-kV (X-13/X-20), rebuild existing double circuit | 9 | 2024 | Reliability |
| Hillman–Darlington 138-kV line (X-14/X-101), rebuild | 10 | 2026 | Condition and performance |
Zone 3 Provisional Projects
| Project Description | Project # | In-service year | Need driver |
|---|---|---|---|
| None |