1. http://nodal.ercot.com 1 Market Trials Real-Time Market / LFC Weekly Update July 30, 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 –Real Time Market / LFC Update –State Estimator Convergence Statistics –5 Hour Full System Market and Reliability Test Results –24 Hour Full System Market and Reliability Test Update –24 Hour Full System Market and Reliability Test Reminders 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. http://nodal.ercot.com 4 Environment Report: Planned / Unplanned Nodal Outages Planned Outages N/A Unplanned Outages 07/28/2010 01:00 P.M. – 07/28/2010 01:30 P.M. –Users may have experienced intermittent issues in downloading real time LMP data. The root cause of the issue is currently being investigated.

5. http://nodal.ercot.com 5 Known Issues Recently Opened Issues SCED Step One curve generation incorrect when (0 MW, $0) point is in submitted EOC –SCED uses an incorrectly formed energy offer curve when a market participant submits a curve that includes a price/quantity pair of $0 at 0MW. To workaround this issue, market participants should substitute a nearby pair for this point, such as $0.01 at 0MW. NP6-621: SE Load Report - Individual Load on Electrical Buses (MIS Secure) –Sums of loads only represents a percentage of the actual ERCOT load –Affects CDR Recently Closed Issues The following EDW reports had previously been failing with error messages: –NP8-501-Monthly Resource Energy Deployment Performance Report (MIS Certified Report) –NP8-541-Monthly Responsive Reserve Performance Report (MIS Secure Report)

6. http://nodal.ercot.com 6 Standing Reports and Updates: General Reminders / Updates Reminders/Updates Updates to Tracking Artifacts –The Known Issues tracking sheet will refresh overnight to the Readiness center at http://nodal.ercot.com/readiness/markettrials/rtm/index.htmlhttp://nodal.ercot.com/readiness/markettrials/rtm/index.html Network Model Update –The network model database was updated on Friday 7/23/2010 –The next network model database load will occur Monday 8/2/2010 –ERCOT has posted the Redacted Network Model on the MIS -> Grid -> Long-Term Planning page Questions or Issues encountered during Full System tests –Please use the markettrials@ercot.com address before, during, or after any test for problems or clarificationsmarkettrials@ercot.com

7. http://nodal.ercot.com 7 Standing Reports and Updates: General Reminders / Updates Reminders/Updates Nodal Public Reference Data Extract Updates (see July 27 th Market Notice) –Updates will post on the MIS on 8/3/2010 –Updated version 0.16 DDLs and XSDs included in “PRDE Extract User Guide” at http://nodal.ercot.com/readiness/reports/index.htmlhttp://nodal.ercot.com/readiness/reports/index.html 24 Hour Full System and Reliability Test Window (see July 27 th Market Notice) –August 3 rd, 4 th, or 5 th window announced. See “24 Hour Full System and Reliability Test” updates for more details.

8. 1/22/2016 http://nodal.ercot.com 8 Real Time Market / LFC Update

9. http://nodal.ercot.com 9 SCED Week 26 System Lambda at $2250 offer cap for 381 intervals (compared to 93 last week) SL $2251-$3000 for 15 intervals; $3001 for 123 intervals EOC submissions down to 92% from normal of 99%

10. http://nodal.ercot.com 10 State Estimator Convergence

11. http://nodal.ercot.com 11 State Estimator Convergence Update State Estimator Daily Convergence Statistics (these percentages are graphed in the next slide) MonthDay% Convergence (Including Solved w/ Mismatch) JUL1999.66 JUL2098.65 JUL2198.00 JUL2297.60 JUL2396.68 JUL2499.27 JUL2599.64 JUL2699.65 JUL2799.31 JUL2897.87

12. http://nodal.ercot.com 12 State Estimator Convergence Update Need Updated

13. 1/22/2016 http://nodal.ercot.com 13 5-Hour Full-System Market and Reliability Test Results Stacy Bridges

14. http://nodal.ercot.com 14 5-Hour Full System Reliability and Market Test Results 5-Hour LFC Test (7/21/2010) TimeActivity 0800 Hotline call was made by the ERCOT Operator announcing the 1100 start time for the test 0929ERCOT Operators activated an OC3 for solving congestion in Zonal 1100 Hotline call what made announcing the test was starting and the VDI was issued 1119First participating QSE confirms switch over to Nodal control 1214Final participating QSE confirms switch over to Nodal control 1218 Hotline call what made announcing that all participating QSEs on Nodal control 1531 Hotline call what made announcing that participating QSEs were being switched back to Zonal 1535First participating QSE confirms switch back to Zonal control 1616Final participating QSE confirms switch back to Zonal control

15. http://nodal.ercot.com 15 5-Hour Full System Reliability and Market Test Results Constraints Encountered During the Test StartConstraintReason 10:00Roanoke Switch OC3Loss of Roanoke Switch T1 345/138KV autotransformer overloads West Denton - Fort Worth Substation 138KV - 108% of 218 MVA rating. 12:20Jack County - Reno OC3Loss of Jack County - Reno 138KV overloads Wise County - Bridgeport TU 138KV - 105% of 199 MVA rating.

16. 5-Hour Full System Reliability and Market Test Results http://nodal.ercot.com 16 Commons Issues Seen During the Test Net MW different between zonal and Nodal Three Part Offers Missing Three Part Offers Not covering full range of generator (compared to HSL) JOU units providing inconsistent data between owners Several issues where RARF data incorrectly submitted and limiting actions during the test (e.g. LRL set too high, Ramp Rate Reasonability Limit set too high, etc) Telemetry coming in suspect AS telemetry inconsistent between zonal and nodal Using Lower / Raised block status to operationally control unit's limitations Invalid Resource Status Codes (e.g. RST = 0) Incorrect Resource Status Codes (Generating, but offline and available MW output greater than HSL

17. http://nodal.ercot.com 17 5-Hour Full System Reliability and Market Test Results

18. http://nodal.ercot.com 18 5-Hour Full System Reliability and Market Test Results Frequency

19. http://nodal.ercot.com 19 5-Hour Full System Reliability and Market Test Results CPS1 Score CPS1 During the 7/21/2010 5-Hour LFC Test: CPS1 Score (1 Min.) Average All in Zonal (1000-1119)115.01 Transition to Nodal (1119-1214)88.60 All in Nodal (1214-1535)110.50 Transition to Zonal (1535-1616)119.05 All in Zonal (1616-1800)176.61 CPS1 Score (1 Min.) Average by Hour HE 11140.14 HE 1273.19 HE 13110.94 HE 14105.53 HE 15120.02 HE 16104.08 HE 17160.68

20. http://nodal.ercot.com 20 5-Hour Full System Reliability and Market Test Results Nodal Generation to Be Dispatched and Load

21. http://nodal.ercot.com 21 5-Hour Full System Reliability and Market Test Results Regulation and System Load

22. http://nodal.ercot.com 22 5-Hour Full System Reliability and Market Test Results Regulation and System Frequency

23. http://nodal.ercot.com 23 5-Hour Full System Reliability and Market Test Results Regulation and ACE Scores

24. 5-Hour Full System Reliability and Market Test Results http://nodal.ercot.com 24 Regulation – Zonal vs. Nodal

25. 5-Hour Full System Reliability and Market Test Results Frequency vs. Expected Output Deviation http://nodal.ercot.com 25

26. 5-Hour Full System Reliability and Market Test Results Completion Criteria: –The rolling CPS1 one minute average score must equal or exceed 100% during the test period. Note that CPS1 metric will not apply to periods during testing wherein system tuning is being performed by either ERCOT or Market Participants –HE12-73, HE13-112, HE14-103, HE15-120, HE16-103 –Zonal Commercially Significant Constraints (CSCs) and Closely Related Elements (CREs) managed below thermal limits. The Zonal CSCs were not activated during the test –Local Congestion managed below thermal limits. Two local constraints binding during the test –Stability limits managed below transfer limits No stability limits were activated during the test –No NERC Disturbance Control Standard (DCS) failure if applicable Not applicable during the test –No LFC-SCED system issues that result in termination of the test. No –Procedural and software fixes have been verified to address lessons learned from previous rounds of testing Migrated patches into NPROD and verified prior to the test. There were no shift factors transfer failures during the test. Note: The individual QSE GREDP analyses from the 5-Hour test will be distributed the week of July 26 th http://nodal.ercot.com 26

27. http://nodal.ercot.com 27 5-Hour Full System Reliability and Market Test Results Gredp Analysis For this analysis; X=5%, Y=5 MW, and Z=10% Performance does not appear to have varied drastically from the 8-hour test Criteria: Non-IRRs must have a GREDP less than X% or Y MW for 85% of the intervals in which GREDP was scored IRRs must have a GREDP less than Z% or the output must be less than their expected output for 95% of the intervals in which GREDP was scored Percent of Non-IRR Generation Resources that Met the Protocol Criteria All Resources 79.74% Resources Providing Regulation 86.90% Combined Cycle Resources 93.22% Coal and Lignite Resources 97.50% Diesel Resources 100.00% Gas Steam (Non-Reheat Boiler) Resources 25.00% Gas Steam (Reheat Boiler) Resources 72.22% Gas Steam (Supercritical Boiler) Resources 33.33% Hydro Resources 88.89% Nuclear Resources 100.00% Simple Cycle (Greater than 90 MW) Resources 100.00% Simple Cycle (Less than 90 MW) Resources 34.04% Percent of IRRs that Met the Protocol Criteria 33.33% Number of IRRs that had an Interval for which GREDP was scored 9 IRRs Non-IRRs

28. 5-Hour Full System Reliability and Market Test Results CPS1 scores did seem to improve during periods in which GREDP performance improved Period during test in which performance was not calculated due to a protocol GREDP performance exclusion http://nodal.ercot.com

29. http://nodal.ercot.com 29 24-Hour Full-System Market and Reliability Test Update Stacy Bridges

30. http://nodal.ercot.com 30 24-Hour Full System Reliability and Market Test Update 24- Hour Full-System Market and Reliability Test Timeline –The 24-Hour Workshop was provided during the 7/23 RT Market Call http://www.ercot.com/calendar/2010/07/20100723-MT –The 24-Hour Test will be conducted Aug 4 – 5 –Proposing a start time of 12pm Market Notices –A Market Notice was sent July 27 confirming the upcoming 24-Hour test –A follow-up notice to be sent today (7/30) confirming Aug 4 as the start day –A final Market Notice will be sent on the day of the test to confirm that the test will be conducted that day Other details –On the test day, a hotline call will confirm the start time of the test (approximately 2-3 hours prior to start) A market-facing WebEx conference will be provided—WebEx details will be emailed to Nodal Transition Project Managers the week of the test –ERCOT and Market Participant staff should be available and ready to field troubleshooting calls at 8am on the first day of the test –A System Wide VDI will be issued immediately prior to the start of the test

31. http://nodal.ercot.com 31 24-Hour Full System Reliability and Market Test Update 24- Hour Full-System Market and Reliability Test (continued) Proposed Tuning Windows –ERCOT system-tuning windows: Window One: 4 – 6 PM (on the starting day of the test) Window Two: 6 – 8 AM (on the ending day of the test) Note: Any adjustments to the timing of these tuning windows will be communicated as the windows draw near –Market Participant system-tuning windows: Proposing that MPs who wish to perform system tuning do so during times that do not overlap with the following test activities: –Zonal  Nodal /Nodal  Zonal switchover activities –Operational scenarios –ERCOT system tuning windows

32. http://nodal.ercot.com 32 24-Hour Full System Reliability and Market Test Update 24- Hour Full-System Market and Reliability Test (continued) Operational Scenarios –Issue Non-Spin Deployments ERCOT plans to issue Non-Spin Deployments to Generation Resources during the 24-Hour LFC Test –ERCOT will deploy a small MW quantity of Non-Spin to offline Generation Resources that have a zonal Non-Spin obligation during the test period –The Non-Spin will be deployed first in zonal and then will be deployed to the same QSEs/Resources in nodal The scenario is expected to last approximately one hour Hotline calls will be used to announce the start and end of this scenario

33. 24-Hour Full System Reliability and Market Test Update Support from the Market Participants Each Market Participant will need to have their experts on hand during normal business hours (8:00 am – 5:00 pm) each business day during the week of the test until the completion of the test Support hours will need to be extended on test day –During the day of the test, the hours of support will need to be extended from 8:00 am on the test starting day until 12pm on the test completion day: http://nodal.ercot.com 33 Aug 4Aug 5 Day One of Test Day Two of Test

34. 24-Hour Full System Reliability and Market Test Update Support from the Market Participants (continued) Support staffing for this testing should be reflective of the level of staffing that is planned for nodal post-go-live Market Participants should staff as appropriate to manage Real-Time Nodal submittals and to address issues for the duration of the test ERCOT staff will be contacting MPs during these hours as necessary to support ICCP, Market Submittals, LFC http://nodal.ercot.com 34 Day One of Test Day Two of Test

35. http://nodal.ercot.com 35 24-Hour Full System Reliability and Market Test Update Requesting Updates to Nodal Contacts for 24-Hour LFC Test QSEs with Resources are requested to review their Nodal Contact information as previously submitted per the Contact Declaration Form and make any necessary changes for contacts who will be supporting ICCP, LFC, Market Data Submittals The current Nodal Contact Declaration Form v1.1 is available at http://nodal.ercot.com/readiness/rq/documents/index.html http://nodal.ercot.com/readiness/rq/documents/index.html Submit any updates or questions to nodalmarkettransition@ercot.com by 12:00pm on August 2, 2010nodalmarkettransition@ercot.com Designate day and night contact by (D=Day, N=Night) In addition, please ensure that the contact information for your Real-Time desk is accurate so that the ERCOT Control Room can contact you as needed during the 24-Hour LFC Test

36. http://nodal.ercot.com 36 24-Hour Full-System Market and Reliability Test Reminders Stacy Bridges

37. 24-Hour Full System Reliability and Market Test Reminders Manual dispatch instructions during the LFC test Beginning two hours prior to the LFC test, ERCOT will stop using OC1s and OOMEs and plans to use OC3s to manage congestion –The one exception to this is that ERCOT will use OC1s for the W-N and the N-H stability limit (non-thermal IROL for NERC) during transition periods to and from Nodal control –ERCOT has created and tested constraints for these limits in the Nodal system which can be activated for SCED as needed and should provide similar dispatch to the OC1s ERCOT may be required to use Zonal manual dispatch instructions to solve congestion ERCOT will set the Nodal Base-Point to match the Zonal manual dispatch instruction The QSE will continue to follow the Nodal Base Point if they are still under Nodal control http://nodal.ercot.com 37

38. http://nodal.ercot.com 38 24-Hour Full System Reliability and Market Test Reminders RSTs to be used during Ramp-Up / Ramp-Down RST during Ramp-Up: Between 0 MW and LSL, the telemetered RST should indicate online status SCED will dispatch the Resource to its current output Between LSL and HSL, the telemetered RST should reflect unit activity per the Resource Status Codes provided in the Nodal Protocols RST during Ramp-Down (to OFF): Use RST of “OFF” to take unit out of pool of Resources available for economic dispatch by SCED This method is being suggested for purposes of LFC Testing and may not be the method used for nodal market go-live RLC will set HDL/LDL that it passes to SCED such that the Resource will be ramped offline

39. 24-Hour Full System Reliability and Market Test Reminders Non-Spin Deployment (Nodal and Zonal system) If required, Non-Spin will be deployed from the Nodal system during the 5-Hour LFC Test (this is not a formal operational scenario for this test) Zonal will also continue to deploy Non-Spin When Non-Spin is deployed in one system, ERCOT will select the same QSE/Resources for deployment in the other system QSEs are requested to keep their telemetered Resource Status Codes, Non- Spin Responsibilities, and Non-Spin Schedules in Nodal reflective of their Zonal Non-Spin obligation After a Non-Spin deployment, QSEs must also update their Nodal EOCs, Output Schedules, Telemetered Resource Status Codes, and Resource Limits in preparation for Resources coming online so that SCED can dispatch Resources appropriately once they become available The QSE should also adjust the telemetered NSRS Schedule in the Nodal system to reflect the Nodal deployment http://nodal.ercot.com 39

40. http://nodal.ercot.com 40 24-Hour Full System Reliability and Market Test Reminders Market Participant EMS Wind Unit Data Note Set Real-Time telemetered HSL value to current MW output per (NP 6.5.5.2(3)) Additional detail was added to this protocol reference as part of NPRR 214NPRR 214 If the Wind-Powered Generation Resource (WGR) is not being curtailed, the HSL should be set at the actual net output of the WGR In event of curtailment (i.e., a SCED instruction at least two MW lower than the unit’s current MW output), the HSL should be set at the capability that the facility would have if it were not being curtailed This estimate should be based on wind speed, power curves, and turbine availability The QSE shall set the HSL within one SCADA cycle after receiving a SCED Base Point Dispatch Instruction from ERCOT This will allow the QSE to more easily detect if the WGR must respond to a curtailment instruction

41. http://nodal.ercot.com 41 Questions Q&A