1. Engineering a sustainable future 1 ERCOT Voltage Ride-Through Study Workshop June 26 th, 2009

2. Engineering a sustainable future 2 Agenda  PB Introduction  VRT Study Scope  Data Requirement from Wind generator Owners  Data Requirement Schedule  Q&A

3. Engineering a sustainable future 3 Agenda  PB Introduction  VRT Study Scope  Data Requirement from Wind generator Owners  Data Requirement Schedule  Q&A

4. Engineering a sustainable future 4 PB – working with clients worldwide and meeting their needs for over 100 years Comprehensive project management services and technical excellence - helping clients deliver sustainable solutions

5. PB Power Worldwide Capabilities Boston San Francisco Kuwait / UAE Singapore Newcastle Major Power Technical Centers Dallas / Houston Wellington/Auckland Manchester / Godalming New York Brisbane Global expertise - local understanding

6. Engineering a sustainable future 6 VRT Study Team Mandhir Sahni, PhD Yunzhi Cheng Project Manager Sunil Talati, P.E. Phase I Mandhir Sahni, PhD Yunzhi Cheng Phase III Lloyd Pasley Phase II ERCOT Project Managers John Schmall, P.E. José Conto QA/QC Jeyant Tamby, PhD-Sungard Principal-In-Charge Eric C. Swensen, P.E. Other Support Staff

7. Engineering a sustainable future 7 ERCOT WGRs PB Communication Protocols For Data Collection Only

8. Engineering a sustainable future 8 NDAs ERCOT WGRs PB Equipment Manufactures PB will share data with ERCOT PB’s Standard NDA

9. Engineering a sustainable future 9 Agenda  PB Introduction  VRT Study Scope  Data Requirement from Wind generator Owners  Data Requirement Schedule  Q&A

10. Engineering a sustainable future 10 VRT Study Overview Determine if there are any system reliability risks associated with existing wind plants (with an IA signed prior to November 1, 2008) that do not comply with ERCOT VRT requirements

11. Engineering a sustainable future 11 VRT Study Overview  Phase I  Dynamic simulations utilizing existing ERCOT model data set  High wind – High load  High wind – Low load  Phase II  Verify wind plant modeling and develop model improvements as necessary  Phase III  Dynamic simulations utilizing updated models based on model verification  Test sensitivities and mitigation as necessary

12. Engineering a sustainable future 12 Project Schedule  Phase I  Completion by September 2009  Phase II  Completion by December 2009  Phase III  Completion by April 2010 VRT Study Overview

13. Engineering a sustainable future 13 Phase I Study Cases  System Topology  SSWG 2009 DSA Fall Cases  ~9400 MW Wind Capacity  High Wind – High Load Scenario  ~58000 MW ERCOT System Load  ~4800 MW Wind Output (West Texas)  N-1 Security Constrained Generation Dispatch  High Wind – Low Load Scenario  ~36000 MW ERCOT System Load  ~4300 MW Wind Output (West Texas)  N-1 Security Constrained Generation Dispatch

14. Engineering a sustainable future 14 Contingency Selection It is necessary to select a limited set of contingencies for dynamic simulation  Single Line/Double Circuit Contingencies  Three-Phase Faults with Normal Clearing  Single-Phase Faults with Delayed Clearing (Breaker Failure)

15. Engineering a sustainable future 15 Contingency Selection  Contingency Selection Process  Fault Analysis  Identify fault locations that cause the greatest voltage drop at wind plant POIs  AC Contingency Analysis  Identify contingencies that result in the lowest post-contingency voltages  Identify contingencies that result in the greatest decrease in voltage  PV Analysis  Identify contingencies that are most critical with respect to voltage stability  West Texas export transfer scenarios

16. Engineering a sustainable future 16 Wind Plant Model Verification Network Additions Collector System Equivalent Pad-Mounted Transformer Equivalent Shunt Devices & Control Schemes

17. Engineering a sustainable future 17 Phase II Process PB Will Collect Modeling Data Directly From Wind Plant Owners  Model Development for ALL Wind Plants  Wind Plant Model Will Require Some Form of Owner “Approval”

18. Engineering a sustainable future 18 Phase III Process Perform Dynamic Simulations Utilizing Enhanced Wind Plant Models  Evaluate Up To Six Additional Scenarios  Variation in generation dispatch (conventional and/or wind)?  VRT capability added to wind plants?  Addition of reactive resources?  Variation in the load model?  Scenario Selection Dependent on Initial Simulation Results

19. Engineering a sustainable future 19 Agenda  PB Introduction  VRT Study Scope  Data Requirement from WGRs  Data Requirement Schedule  Q&A

20. Engineering a sustainable future 20 Phase II Steps  Step 1 – Build Consensus  Data Request Forms (DRF) approval from ERCOT and TSPs  Sign confidentiality agreements with equipment vendors and WGRs  Step 2 – Conduct Workshop  Conduct Workshop with WGRs  Step 3 - Collect and Validate data submitted by WGRs  Existing WGR models for operating units  WGR models for planned units  Step 4 – Prepare Equivalent Circuit for individual WGR units

21. Engineering a sustainable future 21 Phase II Scope  Limited to ALL WGRs with an IA signed prior to Nov 1, 2008 Limited to ALL WGRs with an IA signed prior to Nov 1, 2008  Accurate and complete data submittal is essential  Source of information:  ERCOT Wind Data Forms and Models – information submitted during the interconnection study phase  Resource Asset Registration Forms (RARF)  LVRT Status Survey  Design / Construction documents

22. Engineering a sustainable future 22 General Information  Submittal Information  Date format shall be MM/DD/YYYY  Resource Entity name must match ERCOT’s record  Resource Entity Authorized Representative  As registered with ERCOT  Responsible for submission of RARF to ERCOT  Primary Contact / Technical Contact  Site or facility contact for Generation Resources  May be Authorized Representative Provide your contact information by Monday, June 29 th, 2009.

23. Engineering a sustainable future 23 Facility One Line Diagram TSP Substation Data Transmission Line Data Relaying and Protection Scheme Transformer Data Collector System Substation Data Collector System Data

24. Engineering a sustainable future 24 Collection System Diagram UG Cable Layout & Size Turbine Location, Type and Size

25. Engineering a sustainable future 25 Collection System Data

26. Engineering a sustainable future 26 Collection System Data

27. Engineering a sustainable future 27 Updated Data Forms Provide comments on the attached data forms by Thursday, July 2 nd, 2009.

28. Engineering a sustainable future 28 Agenda  PB Introduction  VRT Study Scope and Challenges  Data Requirement from WGRs  Data Requirement Schedule  Q&A

29. Engineering a sustainable future 29 Data Requirement Schedule  WGRs to provide completed General Information form by Monday June 29 th, 2009.  WGRs to provide comments on VRT Data Request Forms by COB Thursday, July 2 nd, 2009.  PB will submit updated VRT Data Request Forms to WGRs by COB Friday, July 10 th, 2009.  WGRs to submit completed VRT Data Request Forms by COB Friday July 31 st, 2009.

30. Engineering a sustainable future 30 PB Contact Information Sunil Talati PB Power 2777 Stemmons Freeway Suite 1520 Dallas, TX 75207 Ph 214-678-1190 Cell 214-649-7365 Email: talati@pbworld.com

31. PB Team