Review of After-the-Fact (ATF) Tagging Criteria Scheduler’s Meeting May 24, 2016 Raymond will ask the audience what their expectations are in regard to ATF tagging presentation. What do they want to learn or clarify? RAYMOND r. VOJDANI, PE

Review of ATF Tagging Criteria Background ATF Transactions Has Been Getting a Lot of Publicity There Is a Movement to Limit or Eliminate ATF Changes All together There is Confusion as when ATF Transaction is needed or warranted Purpose Review the ATF Tagging Guideline Provide Education and Guidance on When ATF Tagging Should be Used Background - Raymond will review the number of ATF transaction in recent years and emphasize the necessity to eliminate or minimize the number of ATF tags. Purpose – Raymond will articulates the purpose and goal of this presentation

Review of ATF Tagging Criteria REASON 2016 2015 2014 2013 2012 Incorrect Path or Sched Entity 3 66 56 82 72 Scheduling or Adjusting Error 21 20 16 36 System Error   12 27 Generation/Meter Adjustment 6 50 40 26 31 Incorrect Source / Sink 2 13 203 11 Curtailment Error Incorrect PSE 1 8 5 RSG Tag Error 9 18 Integration Error 4 Tag Type Correction 49 Incorrect Tag 68 WIT not match OATI Tag Oversold Unknown No Original Tag TOTAL 28 236 383 199 231 Originally Reported 88 87 Current MW 749 5840 22662 1679 12896 Changed to MW 84 2301 9614 1365 7691 Total MW Change 665 3539 13048 314 5205

Review of ATF Tagging Criteria Rule of Thumb as When ATF Tag Should be Used To accurately reflect what had occurred during the real-time What Did the BA Control to What transmission path/s were used To Correct a Critical Issue Which Was Not Caught Real Time When ATF Tag Should NOT be Used To eliminate energy imbalance or generation imbalance within a BA When Creation of ATF Tag creates Inadvertent Interchange for the BA

Review of ATF Tagging Criteria Introduction Overview of Some Basic Definitions Balancing Authority Interchange Interchange Transaction E-Tag Interchange Schedule Dynamic Schedule Automatic Generation Control (AGC) Area Control Error (ACE) Inadvertent Interchange Western Interchange Tool (WIT). Raymond will go over some basic definition used in electric power system

Review of ATF Tagging Criteria How Does an e-tag Become a Schedule A RFI (Request for Interchange) Is Created by One of the PSEs The WECC Interchange Authority Distributes the e-tag to All Affected Parties The RFI Goes Through Appropriate Approval by Affected Parties PSEs, TSPs, BAs, and Sometimes SEs Once the e-tag is Approved, hen a Schedule Is Created in WIT The WIT Schedule Is Reflected in All Impacted BAs (From Source BA to the Sink BA) The BAs use the Schedule and Control Their EMS and AGC Based on the Their Net Schedule Interchange (sum of all schedules) Any Subsequent Changes to WIT Schedule Has to be Done By Modifying an Existing e-tag, Creating a New e-tag, or Deleting the Schedule in WIT

Review of ATF Tagging Criteria Synopsis of a Scheduling Issue and ATF Clean up One BA (BA1) has load in another BA (BA2), the load is dynamically scheduled There was a transmission outage in BA2, so BA1 had to arrange with alternative transmission provider and create a new e-tag using the new TSP The BA1 submits an emergency tag, all parties approve the tag The BA1 realizes that they have made an error and they submit a withdraw request (denied), submit an adjustment (denied), so the original tag stays in place BA1 not realizing that their withdrawal request and adjustment request is denied, submits a new Dynamic tag Now we have two tags in effect, distorting the situation ATF Efforts to zero out one of the schedules (WIT Request Change) goes nowhere (one of the affected BAs, BA3, refuses to sign the WIT Change Request Form) Meanwhile, the Primary Inadvertent Interchange is reflecting a wrong value and both BA1 and BA2 and paying back inadvertent which was calculated based on a wrong NSI Ultimately, the Dynamic Tag was Adjusted to Zero to correct the situation (many days later)

Review of ATF Tagging Criteria Purpose of ATF Tag There was no tag (schedule) for the interchange as agreed by the affected BAs Reserve Sharing Tags Emergency Situation Energy Emergency, transmission loading issues There was a tag but the tag had incorrect information To allow BAS, TSPs, and PSEs to accurately reflect a schedule which was coordinated and controlled by a BA’s EMS and AGC system during real time system operations but was not properly tagged Missing or Incorrect Balancing Authority, TSP, Scheduling Entity Missing Adjacencies or incorrect POR or POD - Incorrect POR or POD could be changed in the e-schedule. Emergency situation when WIT is down The key criteria is to match the tagging system or schedules to what really happened during the real time operation (what did the BAs control to)

Review of ATF Tagging Criteria General Principals for Creating an ATF tag There was no tag created Entities can create a new ATF tag up to 7 days later from the start time Close BA coordination between affected entities is required No Peak RC intervention or submittal of a Form is needed There was a tag but it contain incorrect information If the original schedule needs to be deleted, then, lead BA is to complete the form and coordinate with affected entities for approval If the original schedule needs to be modified (increase MW) then a new ATF tag can be created

Review of ATF Tagging Criteria Logistics of creating an ATF Tag/Schedule Call and/or email all parties involved on the tag when an ATF tag is needed and gain agreement to proceed. Coordinate changes needed within the timeframe for processing/submitting the ATF tag. Route WIT Schedule Change Request Form to all parties for signatures. Submit the WIT Schedule Change Request Form to the WIT Administrator and copy all parties involved. After WIT Administrator responds that the changes have been completed, all parties should verify that the changes were made properly in the WECC Interchange Tool (WIT). Submit the ATF tag by 2:00 p.m. (MST) on the same day that the WIT Administrator makes the changes to WIT, inform all involved parties that the tag is out for approval and reference the new tag number. The lead BA will follow up that ATF tag was approved. Each entity will update its in-house scheduling software to reflect the changes (adjust or zero MW on the original tag schedule) and if necessary verify that the resultant Net Schedule Interchange matches with WIT for that particular hour.

Review of ATF Tagging Criteria

Review of ATF Tagging Criteria Questions ?

NERC Definition of Terms Balancing Authority – The responsible entity that integrates resource plans ahead of time, maintain load-interchange- generation balance within a Balancing Authority Area, and supports Interconnection frequency in real time Interchange – Energy transfers that cross Balancing Authority boundaries Interchange Transaction – An agreement to transfer energy from a seller to a buyer that crosses one or more Balancing Authority Area boundaries E-Tag – An electronic document which details of an Interchange Transaction required for its physical implementation Interchange Schedule – An agreed-upon Interchange Transaction size (MW), start and end time, beginning and ending ramp times and rate, and type required for delivery and receipt of power and energy between the Source and Sink Balancing Authorities involved in the transaction Dynamic Schedule – A telemetered reading or value that is updated in real time and used as a schedule in the AGC/ACE equation and integrated value of which is treated as a schedule for interchange accounting purposes. Commonly used for scheduling jointly owned generation to or from another Balancing Authority Area. AGC – Means equipment that automatically adjusts a Balancing Authority's generation from a central location to maintain its interchange schedule plus Frequency Bias Area Control Error (ACE) – Means the instantaneous difference between net actual and schedule interchange, taking into account the effects of Frequency Bias including correction for meter error. Inadvertent Interchange – The difference between the Balancing Authority’s Net Actual Interchange and Net Scheduled Interchange WIT – Western Interchange Tool – A consolidated Scheduling Software which is used by all the Balancing Authorities in the Western Interconnection to coordinate and document interchange