Xcel Energy Smaller Scale Transmission Projects

2. Xcel Energy Smaller Scale Transmission Projects Northern MAPP Subregional Planning Group April 3, 2007 Srinivas Vemuri, Jason Standing, and Daniel Kline

3. Small Project Information • T-Corners Transformer Replacement • Hyland Lake – Dean Lake 115 kV Upgrade • Woodbury – Tanners Lake Upgrade • Northeast Mankato 69 kV Plan • South Shakopee Substation • Ironwood Second Transformer • Ironwood Bus Upgrade • Lawrence Second Transformer • Tracy Switching Station Capacitors • Keegan Lake – Lebanon Hills • Prescott 10 MVAR Cap Bank

4. T-Corners 115/69 kV Transformer Replacement • Substation currently has two 115/69 kV transformers (#1 & #2) • Tx #1 – 62.5 MVA • Tx #2 – 112 MVA • Summer 2011 – Loss of Transformer #2 will load #1 to 80 MVA (128%) • Plan to replace existing 62.5 MVA bank with matching 112 MVA bank

5. 52 Miles T-Corners 115/69 kV Transformer Replacement T-Corners Eau Claire Metro Area

6. Ironwood Second Transformer • Ironwood 88/34.5 kV Transformer currently rated at 25 MVA • 78 MW generation at Bayfront Substation • Loss of Bayfront 115/92 kV transformer sends Bayfront generation through 88 & 34.5 kV systems • Severely overloads Ironwood – Bayfront 88 kV line • Severely low voltages along Ironwood 34.5 kV system • Add second Ironwood 88/34.5 kV transformer

7. Ironwood Second Transformer

8. Ironwood Terminal Equipment Upgrade • Ironwood – Bayfront 115 kV conductor rated at 189 MVA (850 Amps) • Ironwood 115 kV substation equipment with various ratintgs • 200 Amp CT • 300 Amp Wave Trap • 380 Amp Bus • 400 & 800 Amp Breakers, 600 Amp Switches • Outage of Bayfront – Saxon Pump 88 kV line loads Ironwood 115 kV to 72 MVA (361 Amps) • Outage of Bayfront 115/92 kV transformer loads Ironwood 115 kV to 87 MVA (437 Amps) • Replace capacity-limiting terminal equipment

9. Lawrence Second 112 MVA Transformer • This project is to add an additional 115/69 kV, 112 MVA transformer at the Lawrence Substation in Sioux Falls. This is needed due to the double-circuit outage of the 115 kV line out of Split Rock to Cheery Creek. • In Summer 2011, loss of Split Rock-Cherry Creek and Split Rock-West Sioux Falls double-circuit outage results in a loading of 145.9 MVA (130.2%) of the 112 MVA transformer at Lawrence.

10. Lawrence Second 112 MVA Transformer

11. Tracy SW 12 MVAR CAP • This project is to replace the existing 5.4 MVAR, 69 kV cap bank at the Tracy Switching Station with a new 12 MVAR cap bank. • In Summer 2006, for loss of the Lyon County 69 kV source, the following buses have low voltage: Walnut Grove = 0.855 pu Tracy SS = 0.856 pu Lake Sarah = 0.860 pu Currie = 0.872 pu Slayton = 0.886 pu Hadley = 0.898 pu Lake Wilson = 0.905 pu

12. Tracy SW 12 MVAR CAP

13. Kegan Lake – Lebanon Hills 69 kV Line Upgrade • Reconductor the 3 #8 CU section of the Kegan Lake – Lebanon Hills 69 kV line to at least 48 MVA. • During 2011 summer peak conditions, the line overloads to 110.5% in the base case.

14. Kegan Lake – Lebanon Hills 69 kV Line Upgrade