EDS 3 Release 5 and 6 Friday Market Updates Sept 05, 2008 http://nodal.ercot.com 1

Submission Metrics Update Updates / Questions / Reminders Agenda Antitrust Admonition SCED Update Submission Metrics Update Updates / Questions / Reminders LFC / State Estimator Update Q&A / Open Forum Roll Call 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. http://nodal.ercot.com 3

Submission Metrics Update 8/23/2008 8/24/2008 8/25/2008 8/26/2008 8/27/2008 N/A 85% 17 86% 14 16 87% 92% COP TPO IDO OS 8/28/2008 8/29/2008 8/30/2008 8/31/2008 9/1/2008 N/A 86% 17 82% 16 79% 18 77% COP TPO IDO OS 9/2/2008 9/3/2008 9/4/2008 9/5/2008 N/A 70% 20 Q 17 87% 15 91% 14 COP TPO IDO OS Submit the following for each trade date: Three Part Offer or Output Schedule EOC only required. Should cover 80 – 120% of cost Min Energy / Start-up may be zero’d out FIP/FOP must sum to 100% COP Only required if submitting an Output Schedule No updates in the adjustment period required Note: a COP is also required in order to submit during the adjustment period (this will be changed to a warning in the next release of MMS  MMS4) http://nodal.ercot.com 4

Updates / Questions / Reminders Unplanned Environment Outages MMS 9/03 09:30 – 10:00AM LMP Reports not publishing to MIS. Middleware process hung – bounced services to resolve. EIP Version 1.16 Sandbox Deployment Follow-up – Both, 1.16 EIS Spec and XSD’s have been posted to the readiness center EIS Specification: http://nodal.ercot.com/readiness/sandbox/documents/index.html XSD’s http://nodal.ercot.com/readiness/sandbox/websvc/index.html Maintenance this weekend The maintenance is not believed to affect the EDS environment http://nodal.ercot.com 5

Updates / Questions / Reminders Technical Communications Workshop Occurred as scheduled on 9/3 ERCOT will host a follow-up next week to cover items we did not have time for in the workshop Market notice will be sent out today with date / times (No RSVP required) Sample of Action Items: Walk through sample JAR files included in the ‘Who am I’ and ‘Boomerang’ samples Consider adding the following sections to the EIP Spec: Certificate and Keystore generation Breakdown of certs, where they are obtained and what they are used for Consider providing a Listener example Accept EIS changes on a weekly basis Notifications over WAN Issues continued to be worked http://nodal.ercot.com 6

LFC Update: Focused SE Days Remaining Focused State Estimator Input Days Start date and time End date and time September 8 12:00 am September 12 11:59 pm Note: Next Week’s test starts on Monday and is a full 5 day test ERCOT has posted the results for 8/12 – 8/14 Focused Input Days on the Readiness Center: http://nodal.ercot.com/docs/pd/eds/eds3/lfcfitr/eds_3_lfc_fit_week_2_report_v_1.0.doc http://nodal.ercot.com 7

LFC Phase III SE Focused Input Testing 8/26 – 8/28 8/26/08 convergence for day: 92.31% 8/27/08 convergence for day: 97.31% 8/28/08 convergence for day: 96.62% http://nodal.ercot.com 8

State Estimator Focused Input Windows 8/26 – 8/28 Summary of Observations 8/26 – 8/28 The following issues affected the test results Telemetry errors were lower then the previous test periods Mismatch between Zonal & Nodal Generation Convergence during the test period was 95.41%. 100% convergence was achieved in 56 of the 72 test hours http://nodal.ercot.com 9

LFC Phase III SE Focused Input Testing 9/02 – 9/04 9/02/08 convergence for day: % 9/03/08 convergence for day: % 9/04/08 convergence for day: % Full report will be made available the week of 9/15/08 http://nodal.ercot.com 10

Q&A Q&A / Open Forum http://nodal.ercot.com 11