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

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 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 = pu Tracy SS = pu Lake Sarah = pu Currie = pu Slayton = pu Hadley = pu Lake Wilson = 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