Slide 1

WECC JSIS April 2012 Slide 2 System Events Slide 3 3 March 24, 2012 @ 15:37 Alberta Separation March 30, 2012 @ 10:20 1,600 MW generation loss in WAPA CM, including both Laramie River units March 30, 2012 @ 16:05 952 MW generation loss at Grand Coulee April 6, 2012 @ 9:38 AC RAS event, drop about 1,400 MW of generation April 20, 2012 @ 15:37 AC RAS event, drop 1,643 MW of generation Summary of WECC Events Slide 4 Alberta Separation Slide 5 Slide 6 Slide 7 Slide 8 Frequency Response Summary Dot size is proportional to size of generation drop Blue = nadir, Red = settle