1. http://nodal.ercot.com 1 TSP Nodal Engagement Market Participant Call ERCOT May 19, 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 Metrics update (includes telemetry) Agenda http://nodal.ercot.com 3

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

5. http://nodal.ercot.com LFC 2 Hour Test Key Points 2 Hour Test will test ERCOT and the Market’s ability to control the grid using Nodal systems Logistics –The Market has been notified of the selected date: 5/20/2010 –ERCOT will re-confirm 8am on 5/20/2010 via the hotline, the webex and a market notice –ERCOT will communicate with the market via hotline and a continuous WebEx session throughout the test in addition to individual QSE calls –The test will not take place any earlier than 11am –The 2 hour period will include switching to Nodal, sustained operations for ~6 intervals (30 minutes) and switching back to Zonal The Market will: –Submit Three Part Offers (TPO) in advance of the operating day TPOs shall be a “deconstruction” of what they are offering in the Balancing Energy Market in Zonal (different from the 80-120% of cost currently being submitted) Note MPs will submit a dry run of their TPOs for operating date 5/13/2010 –Only be “committed” from the Zonal processes –Ignore all instructions from the Nodal DAM and RUC processes –Continuously monitor telemetry –Will have their experts on hand for each possible test day, starting at 8am ERCOT will: –Reach out to MPs with missing or “suspect” offer curves from now until the day prior to the test –Reach out to MPs with telemetry issues now until the day prior to the test –Issue a system wide VDI just prior to the start of the test –Will instruct MPs one by one to switch based on a predetermined order –Monitor sustained operations for 6 intervals (30 minutes) –Will instruct MPs one by one to switch back to Zonal based on a predetermined order –Confirm the initiating VDI has terminated once all QSEs are back on Zonal

6. Update for Network Operations Model http://nodal.ercot.com 6

7. ERCOT TAC Meeting - ROS Report 03/04/2010 Ken Donohoo 7 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

8. 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 Experienced a communication problem with backend services Citrix was unavailable for approx. 2 hours Root cause analysis under investigation Update on Performance Issues: ERCOT released an Oracle patch (as planned) System has been stable since patch Update: Issues with NMMS data templates and data consistency Vendor continues to work on resolution Vendor is currently working on reproducing the issues on their systems Update: Issues with PTC and NOMCR’s Vendor continues to work on resolution Incremental improvement has been made, but several outstanding variances are outstanding http://nodal.ercot.com 8

9. Update for Network Operations Model Telemetry Quality Update ERCOT is wrapping up the effort on missing telemetry and is turning our focus on telemetry quality Per a Market Notice distributed on Tuesday 5/18/2010: ERCOT will be reviewing chronically “suspect” values Inquiries on these points will be communicated via point lists sent directly to MPs (TSPs and QSEs) This effort is targeted for completion by the 8 hr LFC test in June Schedule: Friday, May 21: ERCOT will release a dashboard on the Nodal Readiness Center under Market Trials – Real-Time Market with the total number of suspect quality telemetry points per QSE and TSP. The Dashboard will be located at: http://nodal.ercot.com/readiness/markettrials/rtm/index.html. http://nodal.ercot.com/readiness/markettrials/rtm/index.html On Monday, June 7, ERCOT will give QSEs and TSPs a five business day Notice if their scores will be AMBER or RED on the Nodal Scorecard for MP23. On Wednesday, June 16, ERCOT will light up MP23 on the Nodal Scorecard at: http://scorecard.ercot.comhttp://scorecard.ercot.com http://nodal.ercot.com 9

10. NDSWG Update May 19, 2010 ERCOT Database Load Frequency – NDSWG continues to monitor ERCOT’s progress on weekly model loads. ERCOT has completed four weekly model loads of nodal database so far. NOGRR034 – OWG approved NDSWG comments/proposal and ERCOT is preparing a impact analysis. OWG will bring this NOGRR back for ROS to vote on at their June meeting. An alternate ERCOT proposal to lower metrics to not include planned outages will be available for ROS vote. NPRR146 – ROS approved this NPRR with NDSWG recommendations at their May meeting. ERCOT is working on a Impact Analysis before this NPRR is sent back to TAC for vote in June. 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. TSP’s should review this and provide comments. NDSWG will be scheduling some meetings in the near future to update telemetry standards document.

11. Planning Model activities Supporting Monthly CRR Auction http://nodal.ercot.com 11

12. ERCOT TAC Meeting - ROS Report 03/04/2010 Ken Donohoo 12 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

13. SSWG Nodal Schedule May 21 TSP/SSWG remaining data changes for CRR Model May 25TP output with all changes through 5/21 May 26SSWG meeting – Taylor May 28 ERCOT Topology Processor enhancements delivered June – AugustMake remaining changes to IMM prior to Planning Go-Live 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

14. SSWG Planning Model Activities CRR Related Issues- (as of May 3) Correcting Connectivity Node Groups –Feb 26 TP output: 1063 CNGs needing correction –May 14 TP output: 291 CNGs needing correction 1063 892 863 75 7 721 540 52 2 440 320 291 0 309 291

15. SSWG Planning Model Activities CRR Related Issues- (as of May 14) Get Connectivity Nodes into the correct CNGs (i.e. Fix Topology) Status of missing IDs: Branches and loads –Batch NOMCR applied? –Validation rules in effect? Topology Processor changes –SSWG has submitted a System Change Request related the Topology Processor changes Will ask ROS for approval in June NPRR224 was approved by ROS, will be reviewed by PRS tomorrow Identifying important modeling issues

16. 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

17. Planning Model activities Model On-Demand http://nodal.ercot.com 17

18. ERCOT TAC Meeting - ROS Report 03/04/2010 Ken Donohoo 18 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

19. Planning Go-Live Summary http://nodal.ercot.com 19 Justification of Planning Model Go-Live in 2010 ERCOT understanding that Nodal Planning Model functionality is needed to comply with Nodal Protocols effective Dec 1, 2010 ERCOT understanding that annual planning models will be created using new toolset (ie MOD) based on the Network Operations Model after Dec 1, 2010 Impacts Data sets published in 2011 (for 2012/2015) Impacts Annual CRR Auction conducted in 2011 (for 2012/2013) Potential ERCOT flexibility in 2010 implementation dates ERCOT will work with TSPs (SSWG) and QSE/CRR (NATF) to consider refinement of Planning Model Go-Live sequence to extend from August 2010 go- live to being no later than Dec 1, 2010 ERCOT needs to work with TSPs on details of timing

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. Working Towards Go-Live http://nodal.ercot.com 23 Update on Frequency Model Load ERCOT performed weekly model loads for the month of May Starting in June we will transition to bi-weekly loads The load dates in June are as follows: June 1, 10, 16 NPRRs/OGRRs in discussion NOGRR034- Telemetry Performance (June ROS) NPRR146- ICCP Telemetry/Network Model (May ROS) NPRR219- Alignment NPRR for Outages NPRR224- Remove Dynamic Ratings for Annual Planning Model (ROS)

24. Working Towards Go-Live http://nodal.ercot.com 24 ERCOT recognition that some Nodal Protocols come into effect to align with 12/1/2010 which are weeks or months before go-live on 12/1/2010 TSP Model Changes due by Sept 1, for Dec 1 (per protocols 3.10.1) Outages in parallel/dual-entry to support CRR Auction Model and Go-Live CRR Auction process Oct-Nov 2010 Potential Board action on Nodal Protocols in July for market notice on August 1 for effective date on Sept1 May 25 Nodal Workshop to discuss go-live sequence http://www.ercot.com/calendar/2010/05/20100525-MT

25. Metrics update http://nodal.ercot.com 25

26. Telemetry Quality Task –ERCOT is beginning an effort to clean-up consistently suspect telemetry (1) at the ICCP server and (2) within its EMS applications Data Collection –Phase (1) MP ICCP to ERCOT ICCP –Snapshot in time of suspect/garbage values until SE reports available Schedule –5/21 Dashboard released on Readiness Center – All White –Mid-June – SE Telemetry Metric Reports on the MIS Measures quality over time (not a snapshot) Nodal Metric MP23 Telemetry Quality will not begin until those reports are available Communication –ERCOT’s EMS Production Support team will work directly with MP ICCP contacts. ercoticcpsupport@ercot.com –Regular updates at NDSWG and on the bi-weekly TSP market calls http://nodal.ercot.com 26

27. Telemetry Quality http://nodal.ercot.com 27 Telemetry Quality figures are based on snapshots of suspect telemetry coming from Market Participants into ERCOT's Nodal ICCP servers. These snapshots will be taken once a week and this dashboard will be posted on the Nodal Readiness Center (nodal.ercot.com) -> Market Trials -> Real-Time Market on Fridays. ERCOT will not light up Nodal Metric MP23 "Telemetry Quality (MP to ICCP server)" on the Nodal Scorecard until the SE Telemetry Metrics reports are posted on the Nodal MIS in June. If you have any questions about your telemetry quality snapshot, please e-mail ERCOT ICCP support at ercoticcpsupport@ercot.com. Market ParticipantICCP Link Name5/11/2010 "Total"5/11/2010 "Suspect"% Good AUSTIN ENERGY (QSE)AEN_QSE5502296.00 AUSTIN ENERGY (TSP)AEN_TSP22531099.56 AMERICAN ELECTRIC POWER SERVICE CORP (TSP)AEP_TSP1099917398.43 APX (QSE)APX_QSE1020799.31 BRAZOS ELECTRIC POWER CO OP INCBEP_TSP34994598.71 BRYAN TEXAS UTILITIES (TSP)BTU_TSP562399.47 CENTERPOINT ENERGY HOUSTON ELECTRIC LLC (TSP)CNP_TSP745511598.46 CONSTELLATION ENERGY COMMODITIES GROUP INC (QSE)CON_QSE4923792.48 CPS ENERGY (QSE)CPS_QSE7631498.17 CPS ENERGY (TSP)CPS_TSP27822199.25 CITY OF COLLEGE STATION (TSP)CSU_TSP111199.10 DENTON MUNICIPAL ELECTRIC (TSP)DMET_TSP2602490.77 EDISON MISSION MARKETING AND TRADING INC (QSE)EMT_QSE64296.88 EXELON GENERATION COMPANY (QSE)EPT_QSE2953687.80 FPL ENERGY TEXAS KEIR LLC (QSE)FPL_QSE8932097.76 FULCRUM POWER SERVICES (QSE)FPS_QSE3351296.42 GEUS (TSP)GEUT_TSP1223670.49 CITY OF GARLAND (TSP)GPL_TSP1250299.84 IBERDROLA RENEWABLES INC (QSE)IBR_QSE944750.00 LOWER COLORADO RIVER AUTHORITY (QSE)LCR_QSE736699.18 LCRA TRANSMISSION SERVICES CORPORATION (TSP)LCR_TSP698512398.24 NRG TEXAS POWER LLC (QSE)NRG_QSE12932298.30 ONCOR ELECTRIC DELIVERY COMPANY (TSP)ONC_TSP2157057797.32 BROWNSVILLE PUBLIC UTILITY BOARD (TSP)PUB_TSP305897.38 SOUTH TEXAS ELECTRIC CO OP INC (QSE)STE_QSE9551998.01 SOUTH TEXAS ELECTRIC CO OP INC (TSP)STE_TSP21524597.91 TENASKA POWER SERVICES CO (QSE)TEN_QSE17401998.91 TEXAS-NEW MEXICO POWER CO (TSP)TNM_TSP218312894.14 LUMINANT ENERGY COMPANY LLC (QSE)TXU_QSE13234396.75 XTEND ENERGY LP (QSE)XTD_QSE36313263.64 TOTAL1749