1. Buffalo Ridge Incremental Generation Outlet (BRIGO) Transmission Study Presentation to National Wind Coordinating Committee June 22, 2005 W Grivna, PE of Xcel Energy R Gonzalez, PE of Excel Engineering, Inc.

2. Outline Study Purpose/Goals Background Participants Analysis Results Conclusions/Recommendations Next Steps

3. Study Purpose/Goals Determine feasibility of increasing Buffalo Ridge area generation outlet… by several hundred MW… through “modest” (presumably 115 kV-class) improvements… that could be relatively quickly implemented… while plans for future long-range regional transmission projects continue their evolution.

4. Background Buffalo Ridge is the premier wind resource in MN/SD Transmission improvements under way to increase outlet capacity to 825 MW Further interest confirmed by MISO & WAPA interconn queues Xcel Energy has had specific MW & Energy % mandates All other Minnesota power suppliers now also have renewable energy obligations Result: Intense interest in wind development on the Ridge

5. Transmission map of Buffalo Ridge Area

6. Study Participants Sponsor: Xcel Energy Technical & Economic Analyses performed by Xcel Energy

7. Reviewers/technical support: (MAPP MB SPG) Western Area Power Administration Otter Tail Power Missouri River Energy Services MISO Marshall Municipal Utilities Great River Energy East River Electric Power Cooperative Alliant Energy State regulators (MN/ND/SD) Energy Policy Groups (Wind on the Wires) IPPs

8. Analysis Powerflow: Concentrate on 2007, summer off- peak condition –System intact –First contingency (“n-1”) Requirement: satisfy applicable voltage and loading criteria Identify “existing system” (post-825 MW additions) outlet limits for Buffalo Ridge  Mpls/St Paul deliveries Formulate transmission options Test Options’ performance –Electrical –Financial

9. Cost versus Outlet for Options

10. Complications Reactive power requirements/Voltage Stability Power and Energy losses Load-serving considerations Constructability MISO-WAPA interface North Dakota Export (NDEX) interface Geographic extent of Ridge

11. Results All Options can achieve 300-500 MW of incremental outlet Some Options require extensive additional improvements –Line reconductors & rebuilds –Transformer replacements –Shunt capacitor additions Incremental energy losses are high (25 – 30%) The “best” Options all include a second (independent) Fenton-Nobles Co 115 kV outlet path to the new 345 kV

12. Conclusions/Recommendations Implement “Option 31A” –2 nd Nobles Co 345/115 kV transformer –2 nd Nobles Co-Fenton 115 kV line –Lake Yankton-Marshall 115 kV line –Several shunt capacitor banks –Misc reconductors, equipment upgrades Capable of providing 300 - 500 MW of incremental outlet (beyond 825 MW level) at reasonable cost Provides some incidental load-serving benefits

13. Map of Option 31A

14. Next Steps Coordinate & confirm compatibility with likely long-range plans & identified projects –CapX –Big Stone 2 –MISO NW Exploratory Address adaptation to specific proposed wind gen projects (Need “Yankee fix” if MWs on north Ridge exceed critical level) Coordinate with MISO stability study results Initiate permitting process