1. http://nodal.ercot.com 1 TSP Nodal Engagement Market Participant Call ERCOT June 02, 2010

2. http://nodal.ercot.com 2 Antitrust Admonition ANTITRUST ADMONITION ERCOT strictly prohibits Market Participants and their employees who are participating in ERCOT activities from using their participation in ERCOT activities as a forum for engaging in practices or communications that violate the antitrust laws. The ERCOT Board has approved guidelines for members of ERCOT Committees, Subcommittees and Working Groups to be reviewed and followed by each Market Participant attending ERCOT meetings. If you have not received a copy of these Guidelines, copies are available at the Client Relations desk. Please remember your ongoing obligation to comply with all applicable laws, including the antitrust laws. DISCLAIMER All presentations and materials submitted by Market Participants or any other Entity to ERCOT staff for this meeting are received and posted with the acknowledgement that the information will be considered public in accordance with the ERCOT Websites Content Management Operating Procedure.

3. Update for Network Operations Model NDSWG update Planning Model activities SSWG update TSP Outage Scheduler activities Transitioning to Nodal go-live Agenda http://nodal.ercot.com 3

4. Market Trials 2010 Roadmap http://nodal.ercot.com 4

5. http://nodal.ercot.com 5 2-Hour / 8-Hour LFC Test Update

6. http://nodal.ercot.com 6 2-Hour LFC Test Update Test ActivitiesApprox Timeline Market WebEx start8:00 AM ERCOT - MP pre-test troubleshooting period8:00 AM - 11:15 AM Test start11:15 AM Zonal-Nodal cutover11:15 AM - 11:55 AM System frequency controlled by nodal systems11:55 AM - 12:25 PM Nodal-Zonal cutover12:25 PM - 1:00 PM Test end1:00 PM Market WebEx end1:15 PM

7. http://nodal.ercot.com 7 2-Hour LFC Test Update 2-Hour LFC Test Update (continued) Constraints (activated in both Nodal and Zonal)Start Time Garrott - Midtown OC3Loss of Greens Bayou - Gable and Hardy - Crocket 138KV overloads Midtown - Garrott 138KV - 102% of 317 MVA rating. 10:45 AM Bellaire Autotransformer OC3Loss of Bellaire 345/138KV autotransformer 2 overloads Bellaire 345/138KV autotransformer 4 - 101% of 600 MVA rating. 11:45 AM

8. http://nodal.ercot.com 8 2-Hour LFC Test Update 2-Hour LFC Test Update (continued) Common ICCP Issues Identified/Solved During the Test  On/Off status incorrect for LBST/RBST points  Resource Status Codes (RSTs) coming in as SUSPECT  OFF RST being sent for units that were online and generating MW  RST of ON instead of ONREG being sent for units with REG Responsibilities  RST of ONREG being sent for units in hours where they had no REG Responsibility  Non-zero LSLs being sent for WGRs  HSLs for WGRS being set to capacity rather than un-curtailed MW output  MPs updating REG Responsibilities slowly  RegUp & RegDown Responsibilities switched for one another  AS Responsibilities not lining up between Nodal and Zonal (i.e., wrong AS Type or wrong MW value)

9. http://nodal.ercot.com 9 8-Hour LFC Test Update –8-Hour LFC Test Update Workshop to be held on Tuesday 6/8/2010 from 10am – 12pm http://www.ercot.com/calendar/2010/06/20100608-MT Test will occur on the 6/16,6/17 or 6/18 –Announcement will occur 2 days prior to the operating day 8-Hour Approach Document is located at : http://nodal.ercot.com/readiness/markettrials/rtm/index.html http://nodal.ercot.com/readiness/markettrials/rtm/index.html

10. Update for Network Operations Model http://nodal.ercot.com 10

11. ERCOT TAC Meeting - ROS Report 03/04/2010 Ken Donohoo 11 Nodal Model Effort Activity Operations Model (NMMS) CRR Model Topology Processor (Software) Long Term Planning Model NDSWG Support SSWG Support SSWG Support SSWG & ERCOT Development

12. Update for Network Operations Model Network Operations Model Validation: No change 24 of 28 TSPs have submitted confirmation that validation complete Represents 99.9% of the modeled system equipment Materials still available from last TSP validation workshop http://www.ercot.com/calendar/2010/04/20100409-MTTSP NMMS System Update 5/12/2010 – Citrix unavailable UPDATE: Problem with CITRIX appears largely resolved. ERCOT will continue to monitor for performance issues. Please contact NOMCRHelp@ercot.com if you have difficulties. Update on Performance Issues: UPDATE: Problem with oracle appears resolved. No new database issue have surfaced. Update: Issues with NMMS data templates and data consistency UPDATE: Partial fixes have been provided, some data consistency issues have been addressed. Vendor believe that the patches already provided will prevent new invalid data from being submitted, and that the main issue now will be the cleanup of an existing data issues. Update: Issues with PTC and NOMCR’s UPDATE: Issues have been logged in the Vendors defect management tool, and currently they are working on resolutions. No ETA has been provided. http://nodal.ercot.com 12

13. NDSWG Update June 2, 2010 NOGRR034 – On ROS June agenda for vote. An alternate ERCOT proposal to lower metrics to not include planned outages will also be discussed. NPRR146 – On TAC agenda for vote tomorrow. NDSWG is reviewing a draft ERCOT modeling expectations whitepaper. There are TSP operational impacts contained in this whitepaper that affect model coordination, Outage Scheduling, Equipment energization and equipment in-service date management. NDSWG having a special meeting to discuss whitepaper tomorrow (6/3/2010). Still having performance issues with NMMS.

14. Planning Model activities Supporting Monthly CRR Auction http://nodal.ercot.com 14

15. ERCOT TAC Meeting - ROS Report 03/04/2010 Ken Donohoo 15 Nodal Model Effort Activity Operations Model (NMMS) CRR Model Topology Processor (Software) Long Term Planning Model NDSWG Support SSWG Support SSWG Support SSWG & ERCOT Development

16. SSWG Planning Model Activities Correcting Connectivity Node Groups –May 28 TP output: 278 CNGs needing correction 36 CNGs left that ERCOT originally populated with numbers because they could not be matched to an existing PSSE bus TSPs will correct these 36 by June 4 1063 892 863 757 721 540 522 440 320 278 0

17. SSWG Planning Model Activities Status of missing IDs: Branches and loads Phase II Corrections: Area #, Zone #, Load ID, Branch ID, Generator ID –Due July 1 New Topology Processor update delivered to ERCOT –SSWG has submitted a System Change Request (SCR759) related to the Topology Processor changes Will ask ROS for approval in July NPRR224 was recommended for approval by PRS, next step is PRS IA review. Identifying important modeling issues –Categorize these and determine if additional SCRs are necessary

18. SSWG Modeling Issues Annual Planning Model related issues: Off-nominal transformers: TP not calculating impedances correctly? Cap banks and reactors: Control mode in TP output is incorrect in many cases Transformer modeling: 2 winding vs 3 winding No ratings on zero impedance line segments Ownership Loads and cap banks being collapsed to the correct CNGs Cap banks connected to distribution voltage FACTS devices Future versions of PSSE

19. SSWG Nodal Schedule June – AugustMake remaining changes to IMM prior to Planning Go-Live June 4Remaining 99XXXX and 8XXXXX CNG changes due to ERCOT June 7ERCOT to send spreadsheet with Phase II information July 1Phase II changes due to ERCOT July TSPs Complete changes based on TP enhancements July 12-13MOD/PMCR training (email SSWGData@ercot.com to reserve spot)SSWGData@ercot.com July 15-16MOD/PMCR training July 19-20MOD/PMCR training July 22-23MOD/PMCR training AugCompare TP output to SSWG 2010 summer peak case NovCreate 2012 summer peak case using TP and MOD Dec – Feb 2011Review, update, and modify TP/MOD process for case creation Dec 1Nodal Go-Live Mar – April 2011Assuming Nov test meets SSWG approval, begin work to create 12DSA using Nodal method

20. TSP Outage Scheduler activities http://nodal.ercot.com 20

21. TSP Outage Scheduler http://nodal.ercot.com 21 Qualification activities in-flight Weekly Market Call every Friday 9-9:30am http://www.ercot.com/committees/nodal/mt/index Handbook for Outage Scheduler Activities http://nodal.ercot.com/readiness/markettrials/os/index.html OS Qualification Status No change 23/25 TSPs 99.8% complete Equipment Share

22. Transitioning to Nodal Go-Live http://nodal.ercot.com 22

23. De c JanNovOctSe p AugJulyJun Zonal Process Transition Process Initial Validation (ERCOT) Market Validation (Market Participants) Final Validation (ERCOT) NOMCR Processing Cases Used in Production Deadline for Model Changes Nodal Go-Live 168-hr Testing Nodal Production Process Public Posting Transition Plan

24. Transition Plan – Days of Notice Requirements

25. Working Towards Go-Live http://nodal.ercot.com 25 Update on Frequency Model Load Will start with bi-weekly loads after the 6/16 load Closely aligned with Zonal Model load NPRRs/OGRRs in discussion NOGRR034- Telemetry Performance (June ROS) NPRR146- ICCP Telemetry/Network Model (May ROS) NPRR219- Alignment NPRR for Outages Special PRS meeting Apr 19, NDSWG April 20 (PRS) NPRR224- Remove Dynamic Ratings for Annual Planning Model (ROS)