1. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 1 Load Frequency Control (LFC) Business Requirements Energy Management Systems (EMS) August 21, 2006

2. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 2 Agenda Introduction Table of contents Pre-conditions Assumptions ACE Calculation [FR#s: 1-3] Regulation Deployment and Recall [FR#s: 1, 4, 6, 7, 11-16, 18, 21, 23, and 40] Responsive Reserve deployment and Recall [FR#s: 4, 6-8, 12, 14, 21, 23, 26, 27, 29, 32, 40, 42, and 44] Non-Spin Deployment and Recall [FR#s: 12, 33, 35, and 37-39] EECP and Emergency Base Points [FR#s: 23, 25, 27, and 29] Data Communication to QSEs [FR#s: 9, 11, 35, and 43] Protocol Changes Required Questions & Answers and Discussion

3. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 3 L3 Diagram

4. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 4 LFC Data Flow Diagram

5. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 5 Table of Contents –1.Load Frequency Control (LFC)4 –1.1Proposed System Scope4 –1.2Business processes impacted4 –1.2.1Operations Support Engineering:4 –1.2.2Operations Planning:4 –1.3AS Is and To Be Processes5 –1.3.1As Is Monitoring and deploying Ancillary Services5 –1.3.2To Be Monitoring and deploying Ancillary Services6 –1.3.3Differences between the As Is and To Be Sub-Process7 –1.3.4Standard LFC functionality:7 –1.4Preconditions8 –1.5Assumptions and Dependencies8 –1.6Protocol Changes11 –1.7Questions and suggestions from Vendor11 –2.Definitions and Acronyms12 –2.1Definitions12 –2.2Acronyms and Abbreviations19 –3.Functional Requirements21 –4.Supplementary Requirements37 –5.Protocol Coverage38 –6.Sub-Process Coverage40 –Appendix A – Load Frequency Control Level 4 Activity Map41

6. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 6 Pre-Conditions The scope of this document is limited to the functionality derived out of nodal protocols Standard EMS functionality is going to be carried over from the current system Interfacing with NMMS is not in the scope The SCADA interface provides all QSE data communications with LFC

7. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 7 Assumptions Specified data transfers between LFC and MMS will be acceptable to the MMS Vendor If Pseudo unit is deployed by SCED, Base Points of the RRS Generators will be adjusted to account for this MW deployment Pseudo unit deployment will reduce the available responsive reserve

8. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 8 Assumptions (continued) Non-Spin deployment procedure to be approved by TAC will support the following: –ERCOT can deploy all the available Non-Spin capacity from On- Line and Off-Line generators from Energy offer curves –Under normal conditions deployment of Non-Spin Energy is always through SCED –When SCED fails, ERCOT operator manually deploys Non-Spin ERCOT frequency bias will externally calculated Telemetered ramp rates are not going to be used Physical units associated with JOUs are not modeled During RRS energy deployment, generators can not provide regulation if participating in RRS

9. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 9 ACE Calculation Additional term to prevent controlling to an error created by DSR generators moving to their base point Frequency source selection improvements will be made to prevent use of an invalid source that has good data quality

10. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 10 Regulation Deployment and Recall Single signal to each QSE (like present system) LFC sends QSE regulation signal via SCADA QSE regulation participation factor based on telemetered regulation schedules of qualified Generators Generators currently participating in RRS deployment can not be considered for Reg deployment Resource-specific Reg Up and Reg Down MW values are calculated based on telemetered participation factors

11. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 11 Regulation Deployment and Recall (continued) Regulation deployments reset upon receipt of new Base Points from SCED Regulation deployment calculation assumes generators are at their current Base Point LFC calculates non-responding flag for each generator

12. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 12 Responsive Reserve Deployment and Recall Operator initiated in addition to automatic deployment Single signal to each QSE (like present system) All deployment signal to QSEs via SCADA QSE RRS participation factor based on telemetered RRS schedules of qualified Generators LFC calculates RRS resource-specific energy based on telemetered participation factors unless QSEs telemeter their actual MW allocations

13. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 13 Responsive Reserve Deployment and Recall (continued) Operator manually deploys RRS from LAARs Following the RRS deployment, Generator HASLs will be adjusted and SCED will be automatically triggered All RRS deployments (that are dispatched through SCED) will be reset upon receipt of new Base Points from SCED Only during system emergencies, more than 500MW of RRS will be deployed without Operator intervention

14. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 14 Non-Spin Deployment and Recall When needed ERCOT deploys all the available Non-Spin capacity at once While Non-Spin capacity deployment is active, ERCOT may not deploy Non-Spin Energy Deployment of Non-Spin Energy from On-Line Generators with energy offer curves is always through SCED When Non-Spin is deployed, ERCOT sends a portfolio signal to start all the Off-Line generators with Non-Spin Non-Spin available from Load resources will be deployed manually by ERCOT Operator as needed Non-Spin Energy Deployment from On-Line Generators with Output Schedules will be deployed manually

15. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 15 EECP and Emergency Base Points ERCOT Operator manually deploys RRS from Generators based on LFC generated alert message ERCOT Operator manually deploys RRS from Load Resources Emergency Base Points are issued to individual Generators by ERCOT Operator Emergency Base Points to QSEs are communicated through ICCP

16. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 16 Data Communication to QSEs All data communications to QSEs will be using the ICCP interface LFC will receive real-time data from QSEs every 2 seconds LFC will provide output data to QSEs every 4 seconds Regulation and RRS deployment signals to QSEs (as existing system there will be one of each signal per QSE) LFC will send generator Up and Down block signals (to non-regulation generators) to QSEs when generators moving to Base Point is hurting frequency LFC will send generator Base Point data packets to QSEs after received from SCED LFC will send generator Emergency Base Point data packets to QSEs after received from MMS LFC will send all resource node LMPs to all QSEs: –Last solved resource node LMPs will be sent when SCED doesn’t solve –No LMPs will be sent when System Emergency Flag is set LFC sends digital output to each QSE following operator initiation of Non-Spin capacity deployment

17. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 17 Protocol Changes Required The following Protocol changes are recommended: –Section 6.5.7.3(1) to add ACE to the total current generation output level value passed to SCED –Section 6.5.7.6.2.3 (5) to require QSE to keep the Non- Spin Ancillary Service Schedule at the Non-Spin schedule value and not reduce the schedule by the amount of the deployment. –Section 6.5.7.6.2.3 (5) since LFC will calculate new HASL for On-Line Non-Spin generators using a Non- Spin schedule value of zero instead of a value equal to the Non-Spin energy deployed in order to allow SCED to use the entire Non-Spin capacity. LFC will not deploy Non-Spin energy

18. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 18 Protocol Changes Required –Section 6.5.7.2 (3) RRSTELEM will be replaced by RRSAVAILABLE. –Section 6.5.7.2 (5) SURAMP calculation conditionally will use Emergency Ramp Rate when the RRS deployment is active.

19. Texas Nodal © 2005 - 2006 Electric Reliability Council of Texas, Inc. All rights reserved. 19 Questions and Answers & Discussion Questions?