1. TSP WebEx Conference Call Mar 24, 2010 http://nodal.ercot.com 1 Antitrust Admonition 1. Explanation of Validation of Network Model 2. Explanation of Metric MP14C 3. Walk-through of NMMS application 4. Walk-through of data postings that support validation 5. Refresher on creating a NOMCR to correct model 6. Q&A

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. ERCOT TAC Meeting - ROS Report 03/04/2010 Ken Donohoo 3 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

4. SEM Go-Live occurred Aug 31, 2009 ERCOT recognizes issues that were addressed and worked by TSPs related to ownership, outage coordination, and getting used to the NMMS system. Next step is to address status of Post SEM Go-Live –Reflected in SEM Go-Live Procedure and program schedule that 6-months is allocated: –“to ensure that TSPs have sufficient time to synchronize the Nodal Network Operations Model with the TSP’s native model databases, before transitioning to relevant sub- sections of the Nodal Protocol § 3.” –Validation completion planned to be by end of February 2010 –Completion by end of February ensures best SE/SCED solutions which align with 6- months of valid real-time LMPs in schedule, begins March 1 –Completion also significant for Day-Ahead Market begins 30 days later, April 1 Reminder of SEM post Go-Live Activities

5. Update on SEM post Go-Live Activities for Network Operations Model Feb 2010April 2010March 2010 ERCOT applying high volumes of TSP NOMCRs (supporting TSP validation) ERCOT completing RE/ RARFs in model ERCOT releasing GenMap/EPS Meter packages to RE’s ERCOT testing bi-weekly model loads to nodal EMS/MMS ERCOT anticipates TSP validation being ~90% complete RARF should be ~90% complete (Load Resources by 3/15 Model Load) ERCOT staffed to support high volumes of NOMCRs ERCOT anticipates transitioning to maintenance mode for TSP and RARF changes ERCOT releasing RE confirmations of model (RARF as reflected in model since RE’s cannot access) ERCOT formally loading bi- weekly model loads to nodal EMS/MMS on schedule Mar1-TSP metric MP14C becomes Amber for TSPs that have not confirmed validation processing complete Apr1- TSP metric becomes Red for TSPs that have not confirmed validation processing complete Market Trials- Nodal Real-Time Market, State Estimator, CRR Auctions Market Trials- Day-Ahead Market Closed-Loop LFC Tests NDSWG/ROS updates related to Network Operations Model Validation SEM Go-Live 8/31/09 and assessing status of Post SEM Go-Live High-Level view of Validation Progression and related metric http://nodal.ercot.com 5

6. As of March 10 th the current status of completion (measured by MP-14C TSP Model Validation) is: 8 of 22 TSPs have submitted confirmation that validation is complete Represents 66% of the modeled system equipment No TSPs have reported they cannot meet the April 1 deadline Conclusion Nearing completion of process- appears on schedule for April 1 Status of Network Operations Model Validation Metric Name Current Score Applies to WeightGreen %Yellow %Red %Not Scored %Primary CriteriaNotes MP14-C TSP Model Validation AmberTSPs Ownership Ratio Share 66.0%34.0%0.0% Network Model data validated by TSP 8/22 TSPs have submitted model validation e-mail to ERCOT. http://nodal.ercot.com 6

7. TSP Metric http://nodal.ercot.com 7

8. Market Notice from Feb 26, 2010 http://nodal.ercot.com 8 To satisfy the criteria of this metric, an email must be sent by your Accountable Executive, confirming that validation of your portion of the Network Operations Model is complete. The following information below can serve as a guideline for what ERCOT expects in this email response: From: TSP Accountable Executive To: MarketTrials@ercot.comMarketTrials@ercot.com Subject: TSP Model Validation efforts The email should contain a status and/or acknowledgement of the completion of the TSP’s SEM Go-Live activities as it pertains to the metric criteria, which states “validation of the data used for the Network Operations Model will be based on the TSP’s best practices and should align with the following protocol sections: Nodal Protocol § 3.10.7.1 (1) Nodal Protocol § 3.10.7.1.1 Nodal Protocol § 3.10.7.1.2 Nodal Protocol § 3.10.7.1.3 Nodal Protocol § 3.10.7.1.4 Nodal Protocol § 3.10.7.1.5 Nodal Protocol § 3.10.7.2 (4) Nodal Protocol § 3.10.7.2 (7) Nodal Protocol § 3.10.4 (7)” If a TSP’s effort is not complete, ERCOT welcomes a detailed status to be shared with Nodal Program Management to gauge how close the TSP is to completing the validation of their portion of the Network Operations Model. Please be advised of the second deadline, April 1, when the Metric will turn Red if the effort is still incomplete. Market Notices Link: http://nodal.ercot.com/readiness/notices/index.htmlhttp://nodal.ercot.com/readiness/notices/index.html

9. http://nodal.ercot.com 9 FAQ- Access questions Reminder- TSP USA initiates creation of NMMS account. User will receive a new user name and initial password. Please use caution when typing the new password (or removing the trailing space when pasting.) You will be prompted to change your password. If there are any issues with this initial log in, you will receive an error message. At this point, you must request a password reset. –The password can be reset by: 1)Emailing the ERCOT Helpdesk, Helpdesk@ercot.com or calling at 248-6800 option 3.Helpdesk@ercot.com 2)Or contacting your USA – they can reset your password. To reset: in MPIM, select modify to the individual account. There is a check box to reset password. Select the box and email will be sent with new password. USAs were contacted directly with instructions on how to assign the roles for SEM Go-Live Two roles are applicable for NMMS: –NMMS Remote Users (access to production environment to submit NOMCRs) –NMMS_SEMFILE_DOCS (to allow the ability for certain TSP users to download the full network CIM file) –REMINDER to contact NOMCRHelp@ercot.com for any issues/questions.NOMCRHelp@ercot.com

10. http://nodal.ercot.com 10 NMMS Access TSP TML 1)NOMCRs / SAMRs (Report Explorer) 2) CIM network file download capability 3)NMMS Production (also SOTE / MOTE) (links to Citrix Gateway) Citrix Gateway NMMS Production (also SOTE / MOTE) Each TSP Company Folder will contain all Network Model Changes Daily zip files

11. http://nodal.ercot.com 11 Reminders/Tips TSP access to citrix: https://gateway.ercot.com Go to NMMSProd Link For NMMS tool go to PTC-Production For Branch Data files go to

12. http://nodal.ercot.com 12 Reminders/Tips Consider using NMMS System Topology layout to validate connectivity, and using Branch data spreadsheet to validate values (reactance, ratings, etc) NMMS system topology is via NOMCR process (create placeholder project and NOMCR to then “Launch Model Editor”) Branch Data Spreadsheet is in Citrix folder- NMMS Postings, Models, zip file of data Examples of validation: -Breaker/Switch Status -Transformer windings contain most data, only one will contain impedance -Tap Changers- although most values in NMMS are kV, for Tap Changers need to use percent per unit. -As stated above, connectivity in Model editor, data in Spreadsheet

13. http://nodal.ercot.com 13 Reminders/Tips Reminder that NMMS system is in Ohms for resistance or reactance, so TSP may need to covert ERCOT values in Ohms to per unit values for comparing to in-house system.