1. Oil Load Serving Study Update August 18 th, 2011

2. OIL LOAD SERVING STUDY AREA

4. WILLISTON LOAD POCKET

6. ASSUMPTIONS MCDC LIMITED TO 100MW E-W ALSO EXPAND MCDC RUNBACK SCHEME MDU PEAKERS OFF LEWIS & CLARK GEN ON WIND OFF CULBERSTON OFF BUT AVAILABLE FOR PRIOR OUTAGES FORT PECK GENERATION = 35MW, MAX ~135MW WINTER PEAK LOADS

7. CHALLENGES VOLTAGE STABILITY LOW VOLTAGE, POWER QUALITY, POOR “PROFILE” REGIONAL LOAD INCREASES 115KV LINE OVERLOADS MAINLY FEEDING WILLISTON POCKET

8. EXAMPLE VOLTAGE STABILITY “PV” CURVE

9. Charlie Creek EXISTING SYSTEM Charlie Creek-Williston at 115kV 345kV Line 230kV Line 115kV Line

10. Existing System Limit Until July 2012 BASELINE FORECAST Upgrade 115 terminal equipment to 800 amps

11. July 2012 Charlie Creek-Williston at 230kV

12. Capacitor Additions LocationTotal SizeNotes: Dickinson 11530 MVAR Per the Keystone XL initial load requirement. 2 x 15MVAR for switching Logan 11530MVAR2 x 15 MVAR Blaisdel 11530 MVAR2 x 15 MVAR Dunning 11520 MVAR2 x 10MVAR Kenniston 11512 MVAR2 x 6 MVAR Watford City 11530 MVAR2 x 15MVAR for switching State Line 11515 MVAR1 x 15 MVAR SW Minot 11510 MVAR1 x 10MVAR

13. Williston-CCR 230 & Cap Additions BASELINE FORECAST 1080

14. 2013 Networked 115kV Des Lacs

15. Networked 115kV 1080

16. Williston SVC BASELINE FORECAST 1080

17. RUN CULBERTSON PRE-CONTINGENT BASELINE FORECAST 1080

18. ADD 345KV BASELINE FORECAST 1080

19. Prior Outages? Culbertson placed in service MCDC limited to 20MW E-W Tioga-Boundary Dam limited to 0MW S-N

20. Williston-CCR 230 & Cap Additions Networked 115kV BASELINE FORECAST

21. Williston-CCR 230 & Cap Additions Networked 115kV BASELINE FORECAST

22. Williston-CCR 230 & Cap Additions Networked 115kV BASELINE FORECAST

23. QUESTIONS?