Doug Reese, USFEATF Chair USFEATF Report Doug Reese, USFEATF Chair

USFEATF Highlights Power Ball Winning Numbers for March 22 USFEATF most letters in an acronym outside of the Military World record (ADCOMSUBORDOMPHIBSPAC)

USFEATF History and Taskforce Participants The USFEATF was formed at the Spring 2013 Operating Committee Meeting John Tolo (TEPC) – OC Representative Nathan Hunt (NWE) – UFAS Controllable Device Vice Chair Stephanie Conn (WAPA) UFAS Qualified Path Operator Brian Keel (SRP) – PCC Representative Wade Kiess (Peak RC) – Peak RC Robin Chung (BPA) – UFAS Member at Large Raj Hundal (PWX) - MIC Representative Rick Lowther (SRP) – PWG Representative Tim Reynolds (WECC) - Staff Craig Williams (WECC) – Staff Doug Reese (TSGT) – MIC Representative and Chair

Scope of Task Force Analyzed and reviewed twenty-five 2012 USF Events and fifteen 2013 USF Events Identify data and develop methodology to examine USF events on a going-forward basis Produced USF Event Methodology and USF Event Analysis Summary documents Taskforce created a tool that could be easily and consistently used to analyze events

Scope of Task Force Continued Examine existing operating procedures and consider new procedures and tools to monitor and mitigate USF events in real-time Identify Possible USF Mitigation Process Consider Contributing Factors Develop the methodology that is applied for analysis of 2013 events and verify the validity of 2012 analysis Provide routine updates to WECC Members, OC and Board

2012 Contribution Analysis Path Date/time Cause Calculation Mitigation Calculation   De-rate ACE Only USF Only USF & ACE SCH PST SCH- ACE- 66 3/17/12 9:50 Yes  Yes 3/17/12 10:41 3/27/12 6:16 3/28/12 0:11 3/28/12 16:17  Yes 3/30/12 6:23 4/1/12 6:51 4/2/12 17:46 4/13/12 9:06 4/13/12 10:38 4/24/12 4:58 4/24/12 3:02 4/26/12 9:30 5/8/12 15:12 5/20/12 9:35

2012 Contribution Analysis Path Date/time Cause Calculation Mitigation Calculation   De-rate ACE Only USF Only USF & ACE SCH PST SCH- ACE- 66 5/20/12 13:00 Yes 5/25/12 8:04 5/25/12 9:02 6/29/12 0:00 7/13/12 0:31 7/15/12 9:19 Yes  7/20/12 22:00 7/30/12 23:18  Yes 8/1/12 18:03 8/9/12 14:00

2013 Contribution Analysis Path Date/time Cause Calculation Mitigation Calculation   De-rate ACE Only USF Only USF & ACE SCH PST SCH- ACE- 30 1/5/13 16:57 Yes 1/23/13 17:58 2/5/13 6:52 2/19/13 6:26 66 3/3/13 18:26 3/16/13 7:31 36 4/9/13 0:37 4/10/13 13:55 5/13/13 5:53 6/11/13 11:07 7/5/13 11:13 8/12/13 13:02 9/18/13 11:16 10/1/13 23:56 11/16/13 21:17 The USF mitigation procedure for events analyzed by the taskforce involves coordinated operation of phase shifting transformer taps and/or curtailment of schedules (e-Tags) that flow on the overloaded path. For its analysis, the taskforce uses a tool that graphically displays path SOL, actual path flow, scheduled path flow and phase shifting transformer tap positions. The tool also graphically displays the calculated contribution of each Western Interconnection Balancing Authority’s ACE on the path flow. The calculated contribution is the sum of each Balancing Authority’s Inadvertent Interchange multiplied by an inadvertent interchange distribution factor (IIDF) that is derived from the USF Transmission Distribution Factor Matrices. The IIDF is dependent on the path being analyzed and each BA’s default transmission grid interconnection point.

Unscheduled Flow Event Causes De-rate – SOL exceedance caused by unplanned de-rate of path SOL. (path SOL suddenly reduced to less than the actual path flow) ACE – SOL exceedance caused by BA ACE contribution to unscheduled flow on the path. (scheduled flow plus ACE contribution exceeds 100% of path SOL) SCH – SOL exceedance caused by re-dispatch of generation resources resulting from an increase in scheduled path use. (scheduled flow increased by more than the remaining path SOL margin) USF – SOL exceedance caused by unscheduled flow on the path. (scheduled flow plus unscheduled flow exceeds 100% of path SOL) USF & ACE – SOL exceedance caused by a combination of unscheduled flow and BA ACE contribution to unscheduled flow on the path. (scheduled flow plus unscheduled flow and ACE contribution exceeds 100% of path SOL) This slide shows the Event Causes that the Taskforce identified. I am not going to read each one, however, if you would like more information the Unscheduled Flow Event Analysis Methodology and this presentation are posted on the WECC Website if you would like to review it later.

Unscheduled Flow Mitigating Actions “ACE-“ – SOL exceedance mitigated by re-dispatch of generation that reduced BA ACE. (post event ACE contribution reductions are greater than the path SOL exceedance) PST – SOL exceedance mitigated by phase-shifting transformer tap position changes. (PST tap changes correspond to actual path flow reductions greater than the path SOL exceedance) “SCH-“ – SOL exceedance mitigated by re-dispatch of generation resources resulting from a reduction in scheduled path use. (post event scheduled flow reductions are greater than the path SOL exceedance)

Questions ? USFEATF Contact Information Doug Reese – USFEATF Taskforce Chair dreese@tristategt.org 1-303-254-3676 Nathan Hunt – USFEATF Taskforce Vice Chair nathan.hunt@northwestern.com 1-406-497-4177 Steve Ashbaker – Director Event Analysis Ashbaker@wecc.biz 1-801-883-6840