INTERMOUNTAIN POWER PROJECT STABILITY ENHANCEMENT (IPPSE) SYSTEM

1. INTERMOUNTAIN POWER PROJECT STABILITY ENHANCEMENT (IPPSE) SYSTEM Presentation to WECC Remedial Action Scheme Reliability Subcommittee April 30, 2010 Ontario Hilton Ontario, CA

2. INTERMOUNTAIN POWER PROJECT STABILITY ENHANCEMENT (IPPSE) SYSTEM Presented by: • Ken Silver-Electrical Service Manager (Manager of Energy Control and Extra High Voltage Stations ) • Travis Smith-Assistant Manager (Manager of Intermountain Converter Station) • Brian Cast–Electrical Engineer (Grid Operation and Energy Prescheduling Supervisor ) • Ken Lindquist – System Protection Engineer Attendees: • Ken Silver, Mukhlesur Bhuiyan, Travis Smith, Tom Snyder, Brian Cast, Saif Mogri, Ken Lindquist, Carlos Garay and John Hu • Chuck Wu (On Phone)

3. Agenda • System Overview – Ken Silver • Performance and Operational History – Travis Smith • System Studies – Ken Lindquist • System Design – Travis Smith • Arming Function – Brian Cast • Operation and Monitoring – Brian Cast • Operating Procedures for Abnormal Conditions - Ken Silver • Commissioning, Maintenance, and Testing – Travis Smith • Conclusions – Travis Smith

4. 1. System Overview

5. 1. System Overview • The Purpose of Intermountain Power Project Stability Enhancement (IPPSE) is to ensure WECC system stability after outages to the Intermountain Power Project DC system (IPPDC). This is achieved by arming predetermined remedial actions prior to the occurrence of a disturbance associated with the IPPDC. • Due to IPPDC system upgrade from 1920MW to 2400MW, the IPPSE is submitted for review.

6. 1. System Overview Remedial Actions Required: The Intermountain Power Project (IPP) Contingency Arming System (CAS) has been implemented to mitigate IPPDC disturbances by tripping one or two IPP generating units. The IPP CAS has been in operation since 1986. The design and operations of this RAS has been reported to WECC on April 1986 with a report entitled “Intermountain Power Project Contingency Arming System: One Unit Operation” and on August 1992, with a report entitled “Intermountain Power Project Contingency Arming System: Non-Credibility of Remedial Action Scheme Failure.” Formal Operating Procedure: The IPP CAS consists of arming-charts where real-time power output of the IPP generating units and the IPPDC line flows are used to select the no-unit, one-unit or two-unit arming of remedial actions. The IPP CAS and associated operating procedures are included with the LADWP’s Energy Control Center Energy Management System (ECC-EMS) computers.

7. 1. System OverviewIPP DC Upgrade Project

8. 1. System OverviewIntermountain Power Project System

9. 1. System Overview System Map

10. 1. System Overview Intermountain One-line Diagram • One Line Diagram: Adelanto

11. 2. Performance and Operational History

12. 2. Performance and Operational History • The existing IPPSE was installed May 10, 1986 • A design criteria of one operational failure in 3 years was used. • How have we done ?

13. 2. Performance and Operational History • In 24 years there have been 28 actions. Seventeen of which occurred prior to August 1992. • There have been 6 failures 5 of which occurred prior to August 1992. • The system did not achieve its goal from 1986 to 1992. However from 1992 to the present, the system has achieved its goals.

14. 2. Performance and Operational History What Changed in 1992? • A problem with the Monopolar Out signal was discovered and corrected. • A design change was initiated to allow for 1 restart in Monopolar Operation.

15. 2. Performance and Operational History Success • After the modifications, the system operated correctly.

16. 3. System Study

17. 3. Study Process Summary • Co-ordinate with Impacted System Operators (PacifiCorp) in preparing study plan and study conditions. • Determine Impact on the WECC System. • Determine Maximum “IPP Net Import” Capability. • Determine Generation Tripping delay times. • Determine IPP Contingency Arming Scheme (CAS) Operational Nomograms.

18. 3. System Condition Studied IPP DC Upgrade

19. 3. Utah South Conditions TOT2B Stressed TOT2 to Path Rating TOT2C

20. 3. “Net IPP Import” Sensitivity(Post-Transient Power Flow) * IPP DC Will Operate with Maximum “Net IPP Import” of 600MW – Limited by Line Overload

21. 3. Determine Delay Generation Tripping • Accommodate possible DC restart sequence after a DC fault; • To lessen the stress by possibly using a less stressful turbine or boiler trip.

22. 3. Stability Plot for Loss of Bipole with Restart (for DC Fault Only)(Worst Stressed Condition) Trip 1 Unit after First Restart Failed and Second Unit after the Second Restart Failed Trip Both Units after First Restart Failed * CAS Will Trip Units after 1 Restart Attempt Failed

23. 3. Stability Plot for Loss of Bipole with Delayed CAS Generation Tripping for Lower IPP DC Schedule IPP DC Schedule 1500MW IPP DC Schedule 1400MW * CAS Will Delay Generation Tripping for IPP DC Schedule 1400MW or Less

24. 3. Delayed CAS Generation Tripping for Loss of 1 Pole Short Term Overload Capability of IPP DC

25. 3. Delayed CAS Generation Tripping for Loss of 1 Pole (IPP AC Fault Trip 1 Unit + MWC Generations) No RAS Delayed Tripping Fast Tripping * CAS Will Delay Generation Tripping for Loss of 1 Pole

26. 3. IPP CAS Generation Tripping Level Operating Nomogram for Bipole Operation for the Loss of Bipole

27. 3. IPP CAS Generation Tripping Level Operating Nomogram for Bipole Operation for the Loss of 1 Pole

28. 3. IPP CAS Generation Tripping Level Operating Nomogram for Mono-pole Operation for the Loss of 1 Pole

29. 3. Study Summary • IPP DC limited to net AC Import capability of 600MW under maximum Utah South export conditions • CAS will Trip Units after 1 Restart Attempt Failed • CAS will Delay Generation Tripping for IPP DC Schedule 1400MW or Less • CAS will Delay Generation Tripping for Loss of 1 Pole - Limited by Voltage Deviations

30. 4. System Design

31. 4. System Design Design Philosophy • Meet the System Studies Guidelines • Insure Redundancy • Reduce the Hardware • Centralize the Logic

32. 4. System Design Following the guidelines established by the system studies were the driving force in the design of the IPPSE. All parameters of the studies have been met which also allowed for a simpler more efficient design. Only 1 operational failure in 3 years is allowed.

33. 4. System Design

34. 4. System Design • The Bipole Controls are a completely redundant Mach 2 Control System designed by ABB. • All protection actions are routed through this control system. • The IPPSE Logic is fully contained in this system thus reducing the system hardware requirements. • All remedial outputs are generated from this control system.

35. 4. System Design • The remedials from the IPPSE Logic have been simplified into two outputs. • Monopolar Out • Bipolar Out • Based on these two signals and the Nomograms, all IPPSE actions are appropriately taken.

36. 4. System Design Generator Trip Remedials Electrical Trip (86 Lockout) Turbine Trip Boiler Trip

37. 4. System Design IPP Digital Microwave System • Original analog system installed 1985 • System was replaced with Harris Stratex (now Aviat Networks) digital microwave radios in 2004 • LADWP operated and maintained

38. 4. System Design IPP Microwave Power Redundancy • Propane Back up Generators • 24 VDC Power Plants

39. 4. System Design IPP Microwave One Line

40. 5. Arming Function

41. 5. Arming Function Overview: • Arming is automated by an application running in LADWP’s energy management system. • Nomograms, called “charts”, specify the arming level. • Each chart has a series of curves that provide arming levels as a function of IPP net generation (including Milford generation) and the DC line flow. • The application selects charts based on monitored power system conditions and the specific trigger being armed.

42. 5. Arming Function Charts: • One curve per remedial action. • Arming is a function of net gen vs. DC flow. • Top-most curve provides DC flow limit. • Added remedial actions will require an increase in the number of curves per chart.

43. 5. Arming Function Chart Sets: • There may be up to five triggers for remedial actions. • Each trigger has its own arming for remedial action. • Therefore, there is one chart per trigger. • The set of charts for the triggers is a “chart set”.

44. 5. Arming Function Chart Set Selection: • There are multiple chart sets to accommodate varying system conditions. • Chart sets are functionally organized into rows and columns. • Columns are selected based on monitored line flows. • Rows are selected based on line outages and IPP operating modes.

45. 5. Arming Function Chart Set Selection (cont’d): • Original design provided for 24 columns. • Although they no longer affect arming, three power flows are still monitored: Pacific AC Intertie, Arizona–California, and Utah South. • The system study indicates nomogram sensitivity to Utah South power flow, so use of multiple columns may become necessary.

46. 5. Arming Function Imports: • Chart shows a 600-MW import limit. • IPP AC lines have 1317-MW import capability. • Chart is worst-case scenario. • Other cases allow more imports.

47. 5. Arming Function Import Example: • A 72-MW  on Sigurd–Three Peak may allow a 400-MW  in imports. • This can be implemented via multiple columns or via dynamic shifting of affected curves.

48. 5. Arming Function Summary of Arming Function Changes: • Increase in the number of curves per chart due to increase in number of remedial actions. • Decrease in the number of charts per chart set due to decrease in the number of triggers. • Increase in the number of chart set columns and/or addition of dynamic curve adjustments due to varying AC import limits depending on Utah South flow.

49. 6. Monitoring and Operation

50. 6. Monitoring and Operation Overview: • LADWP’s Energy Control Center (ECC) and IPP both have monitoring capability. • The arming application runs at the ECC, but either site can arm manually. • Except for automatic arming, the RAS operation occurs entirely at IPP, but is monitored by both sites. • The slides that follow show monitoring and operation as seen at the ECC.