1. http://nodal.ercot.com 1 Market Trials Real-Time Market / LFC Weekly Update April 2, 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. http://nodal.ercot.com 3 Agenda Antitrust Admonition Environment Report –Planned / unplanned outages –Known Issues Standing Reports and Updates –General reminders / updates –RTM / LFC Update –LFC Update: Status of Individual QSE Tests for LFC –Telemetry Outreach Update –State Estimator Convergence Statistics Question and Answers / General Discussion ERCOT asks that Market Participants log into the WebEx session using their company name and then their name. This will allow ERCOT to take roll-call offline

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

5. http://nodal.ercot.com 5 Environment Report: Planned / Unplanned Nodal Outages Planned Outages –03/29/10 – 03/30/10 06:00 P.M – 06:00 P.M Outbound notifications were turned off as a result of operating day tests conducted on the NPROD environment. Affected notification deliveries associated with MMS and OS submissions. Unplanned Outages –03/26/10 09:00 A.M. – Ongoing Market Manager UI experiencing intermittent periods of unavailability and / or degradation in performance Teams have identified a potential resolution and are working to re-create this in the test environment Work-arounds have been implemented in the Nodal Production environment and have stabilized the issue until a permanent fix is identified –03/31/10 – 04/01/10 08:00 A.M – 7:00 A.M MPs were unable to access Outage Scheduler UI as result of network firewall block. –04/01/10 – 04/01/10 2:15 P.M – 3.15 P.M Experienced access issues with Market Manager and OSRUI applications. Exception occurred as a result of unplanned hardware failover.

6. http://nodal.ercot.com 6 Environment Report: Known Issues Real-Time Known Issues List –The Real-Time Known Issues List was updated April 2 and will deploy overnight to the Readiness Center (http://nodal.ercot.com/readiness/markettrials/rtm/index.html)http://nodal.ercot.com/readiness/markettrials/rtm/index.html New Known Issues: –Five additional defects related to DST short day Closed Known Issues –MPIM - EDC - MPs Unable to Download Certificates Using Win7/Vista or IE8 MPs unable to download certificates using IE version other than IE 6

7. http://nodal.ercot.com 7 Standing Reports and Updates: General Reminders / Updates Network Model Update –The current system loaded from the model 4/1/10 –Next scheduled loads are 4/14/10 and 5/3/10 Market Trials Phase 5 Handbooks are available on Readiness (see April 1 Market Notice): –Real Time Market / LFC Market Trials Handbook http://nodal.ercot.com/readiness/markettrials/rtm/index.html –Congestion Revenue Rights Market Trials Handbook http://nodal.ercot.com/readiness/markettrials/crr/index.html –Outage Scheduling Market Trials Handbook http://nodal.ercot.com/readiness/markettrials/os/index.html –Day Ahead Activities Market Trials Handbook http://nodal.ercot.com/readiness/markettrials/dam/index.html –COMS Market Trials Handbook http://nodal.ercot.com/readiness/markettrials/coms/index.html –MIS Market Trials Handbook http://nodal.ercot.com/readiness/markettrials/mis/index.html

8. 2/29/2016 http://nodal.ercot.com 8 Real Time Market / LFC Update

9. http://nodal.ercot.com 9 SCED Week 9 Friday 3/26 Load spikes due to bad telemetry; LMP not affected as spikes not during SCED run Friday 3/26 6:50 pm anomalous telemetered LMP of $39.64 for one second Weekend LMP highs of $95 and $131 during evening peak—no cap prices

10. Real Time Market / LFC Update http://nodal.ercot.com 10 Wed 3/31 Two Zonal OOME modeled in Nodal as constraints First constraint resulted in one lower RN price of -$50 Second constraint in 5 lower RN prices (-$758), 7 higher RN prices ($279, $416) ZONAL West to North Dynamic Stability constraint was activated 4x last week West to North Dynamic Stability has not yet been modeled

11. http://nodal.ercot.com 11 LFC Update: Status of Individual QSE Tests for LFC LFC Calendar Status 76 QSEs/Sub-QSEs are currently targeted for Individual QSE tests 62 have scheduled a test window (93.95% of Generation) 26 QSE/Sub-QSEs have completed testing (72.98% of Generation): 8 QSEs/Sub-QSEs that have tested will receive a “completed” status pending completion of telemetry clean-up items The LFC Calendar was updated April 2 and will deploy overnight to the Readiness Center http://nodal.ercot.com/readiness/markettrials/rtm/index.htmlhttp://nodal.ercot.com/readiness/markettrials/rtm/index.html BRAZOSFPL_KEIRNRG_TEXASTRQ1_SQ1 CALPINELCRAOPTIM_ENERGYTRQ4_SQ4 CPSLUMINANTOPTIMENERGYSQ1 CPSSQ1NEXTERA_SQ1OXY DIRECTNEXTERA_SQ2RIONGL DIRECTSQ2NEXTERA_SQ3STEC EAGLENEXTERA_SQ4STEC_SQ2 FORMOSANRG_SQ1TENASKA

12. http://nodal.ercot.com 12 LFC Update: Status of Individual QSE Tests for LFC Upcoming LFC QSE Tests Upcoming QSE LFC Tests through April 9: 4/5/10CPS ENERGY 4/6/10MORGAN STANLEY (SQ1, SQ2, SQ3, SQ4) 4/6/10EAGLE (SQ3 & SQ4) 4/7/10BTU QSE 4/9/10PSEG (ODESSA) QSE 4/9/10CALPINE QSE 4/7/10Available Test Window - 9am-2pm Submit questions regarding the LFC Calendar to markettrials@ercot.commarkettrials@ercot.com

13. http://nodal.ercot.com 13 Telemetry Outreach Update TSP Telemetry ERCOT is working with TSPs to resolve remaining telemetry issues in time to support Market Trials Phase 5.0 ERCOT has used commented point lists provided by TSPs to create a bucket list of ~1500 points that need to be resolved New TSP point lists become available April 6 (based on April 1 nodal db load) to indicate progress for this telemetry clean-up effort

14. http://nodal.ercot.com 14 State Estimator Convergence Update State Estimator Daily Convergence Statistics (these percentages are graphed in the next slide) MonthDay% Convergence (Including Solved w/ Mismatch) MAR2298.56 MAR2399.65 MAR2497.76 MAR2593.73 MAR2679.23 MAR2798.94 MAR2899.66 MAR2997.27 MAR3096.30 MAR3199.31

15. http://nodal.ercot.com 15 State Estimator Convergence Update

16. http://nodal.ercot.com 16 Q&A Q&A / Open Forum

17. http://nodal.ercot.com 17 Appendix

18. http://nodal.ercot.com 18 Market Call Schedule Reminder of market call schedule: 09:00 AM-10:00 AM Outage Scheduling 10:00 AM-11:00 AM Congestion Revenue Rights 11:00 AM-12:00 PM Day Ahead Market / RUC / SASM 12:00 PM-01:00 PM Break 01:00 PM-02:00 PM Real Time Market / LFC –WebEx Details will be posted at: http://www.ercot.com/committees/nodal/mt/ http://www.ercot.com/committees/nodal/mt/

19. http://nodal.ercot.com 19 URLS and EMAIL ADDRESS FOR SUPPORT URLs for access the Nodal Production systems –MIS: https://mis.ercot.com/pps/tibco/mis/https://mis.ercot.com/pps/tibco/mis/ –Market Manager: https://mis.ercot.com/pps/tibco/mis/ Click the ‘Applications’ tab in the upper menu. Link is in the ERCOT Applications portlethttps://mis.ercot.com/pps/tibco/mis/ –CRR: https://mis.ercot.com/pps/tibco/mis/ Click the ‘Markets’ Link in the upper menu. Click CRR in the Market sub menuhttps://mis.ercot.com/pps/tibco/mis/ –EWS: https://misapi.ercot.com/2007-08/Nodal/eEDS/EWShttps://misapi.ercot.com/2007-08/Nodal/eEDS/EWS Reminder: Market Trials email address change: ERCOT asks that MPs use the markettrials@ercot.com email address for questions from this point forwardmarkettrials@ercot.com –This will begin the phasing out of eds2@ercot.com, eds3@ercot.com and eds4@ercot.com email addresses.eds2@ercot.comeds3@ercot.com eds4@ercot.com –A centralized address will no longer require MPs to “guess” which email address to use for their questions –We have implemented a more effective method of routing and responding to emails using this address –The old eds emails can continue to be used until 2009 hold over efforts are completed (such as telemetry outreach)

20. http://nodal.ercot.com 20 Market Trials Handbooks –ERCOT will release the following Handbooks In December Real Time Market / LFC covering Phase 3.0 http://nodal.ercot.com/readiness/markettrials/rtm/index.htmlhttp://nodal.ercot.com/readiness/markettrials/rtm/index.html Outage Scheduler covering Phase 3.0 http://nodal.ercot.com/readiness/markettrials/os/index.htmlhttp://nodal.ercot.com/readiness/markettrials/os/index.html CRR covering release Phase 3.0 http://nodal.ercot.com/readiness/markettrials/crr/index.htmlhttp://nodal.ercot.com/readiness/markettrials/crr/index.html Settlements / COMs covering Phase 3.0 http://nodal.ercot.com/readiness/markettrials/coms/index.htmlhttp://nodal.ercot.com/readiness/markettrials/coms/index.html Day Ahead Market (note that this contains only reference data to the 2.1 qualification as there is no Phase 3.0 scope) http://nodal.ercot.com/readiness/markettrials/dam/index.htmlhttp://nodal.ercot.com/readiness/markettrials/dam/index.html –The Phase 4.0 release of the Market Trials Handbooks will occur in early February. –The Phase 5.0 release of the Market Trials Handbooks will occur in March

21. http://nodal.ercot.com 21 Verifiable Cost Submission (originally presented on 4/17) WMS Approved Verifiable Cost Submission Timelines: Simple Cycle Greater than 90MW June 30, 2009 Simple Cycle Less than or Equal to 90MW July 31, 2009 Gas Steam Non-Reheat Boiler Aug 31, 2009 Gas Steam Reheat BoilerSep 30, 2009 Gas Steam Super Critical BoilerOct 31, 2009 Combined Cycle Less than or Equal to 90MW Nov 30, 2009 Combined Cycle Greater than 90MW Dec 31, 2009 Coal, Lignite Jan 31, 2010 Nuclear, Hydro and Renewable Feb 28, 2010 Reciprocating Engines Feb 28, 2010