Oil Load Serving Study Update August 18 th, 2011

OIL LOAD SERVING STUDY AREA

WILLISTON LOAD POCKET

ASSUMPTIONS MCDC LIMITED TO 100MW E-W 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

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

EXAMPLE VOLTAGE STABILITY “PV” CURVE

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

Existing System Limit Until July 2012 BASELINE FORECAST

July 2012 Charlie Creek-Williston at 230kV

CAPCITOR ADDITIONS LocationTotal SizeNotes: Dickinson MVAR Per the Keystone XL initial load requirement. 2 x 15MVAR for switching Logan 11530MVAR2 x 15 MVAR Blaisdel MVAR2 x 15 MVAR Dunning MVAR2 x 10MVAR Kenniston MVAR2 x 6 MVAR Watford City MVAR2 x 15MVAR for switching State Line MVAR1 x 15 MVAR SW Minot MVAR1 x 10MVAR

Williston-CCR 230 & Cap Additions BASELINE FORECAST

2013 Networked 115kV Des Lacs

Networked 115kV

Williston SVC BASELINE FORECAST

RUN CULBERTSON PRE-CONTINGENT BASELINE FORECAST

ADD 345KV BASELINE FORECAST

Prior Outages?

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

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

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

QUESTIONS?