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RECLASSIFICATION OF PALO VERDE TO RUDD AND WESTWING (#2 ) LINE OUTAGE TO CATEGORY D

RECLASSIFICATION OF PALO VERDE TO RUDD AND WESTWING (#2 ) LINE OUTAGE TO CATEGORY D. Presentation to Reliability Subcommittee of WECC. August 26, 2010. Brian Keel, SRP. San Juan. Glen Canyon. Navajo. Four Corners. Mead. McCullough. Moenkopi. Mohave. McKinley. Pinnacle Peak.

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RECLASSIFICATION OF PALO VERDE TO RUDD AND WESTWING (#2 ) LINE OUTAGE TO CATEGORY D

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  1. RECLASSIFICATION OF PALO VERDE TO RUDD AND WESTWING (#2) LINE OUTAGE TO CATEGORY D Presentation to Reliability Subcommittee of WECC August 26, 2010 Brian Keel, SRP

  2. San Juan Glen Canyon Navajo Four Corners Mead McCullough Moenkopi Mohave McKinley Pinnacle Peak Cholla Coronado Westwing Springerville Phoenix PaloVerde Browning Rudd Silver King Kyrene Liberty North Gila Saguaro Yuma Greenlee Tortolita Tucson Non SRP Transmission SRP Transmission (owned or contract rights) SRP Delivery Pt South Vail SRP Transmission Delivery Points Marketplace Pinal West

  3. Palo Verde to Westwing and Rudd Path Westwing Switchyard 19mi Western’s Harcuvar-Buckeye 230kV Line 3.1mi Mead-Phoenix 500kV Line 9.5mi Palo Verde-Westwing 500kV Lines 1 and 2 Liberty-Mead 8mi 345kV Western’s I-10 Parker to Liberty 230kV Line 4.7mi Rudd line is approx. 42 miles Palo Verde Switchyard 31mi 4mi Rudd N 2.2mi West-palo.ppt 8/16/10 /td

  4. Report Outline • Category C to Category D • Path Description – Common Corridor • Path – Sonora Desert Environment • No EHV line crossings for PV-WW Line 2 and PV-RD • Robustness - Mitigating Factors • Design Features • Weather Related Items • Maintenance & Inspections • 6. Configuration of Substations and Tower Failure Analysis • Exposure Analysis • PV-RD and PV-WW Line 2 is the most critical outage is limited to 0 hrs per year currently • Conclusion • 10. Questions and Answers

  5. System Configuration • 2008 Summer Palo Verde Transmission Operating Study • Total Net Generation of 10,406 MW • No Electric High Voltage (EHV) Overhead Line Crossing • For all lines the combined scheduled and unscheduled maintenance according to SRP’s Power Operations is 150-200hrs per year

  6. Mitigating Factors – Aircraft Operations

  7. Mitigating Factors – Lightning and Thunderstorms Mitigating Factors – Winds, No Dust Storms

  8. FLASH DENSITY – SRP SERVICE TERRITORY Flash density in Arizona for all years and months combined from 1984-1993 (1985 and 1986 omitted). Density in flashes per square mile per year shown by scale. Values in gray exceed 8. 500 kV lines in red; 345 kV lines in black. Salt River Project service areas outlined in black. (a) Complete “Figure 2” from NSSL 1995

  9. FLASH DENSITY – SRP SERVICE TERRITORY CLOSE UP VIEW Flash density in Arizona for all years and months combined from 1984-1993 (1985 and 1986 omitted). Density in flashes per square mile per year shown by scale. Values in gray exceed 8. 500 kV lines in red; 345 kV lines in black. Salt River Project service areas outlined in black. (b) Zoom, in on line path with key sites labeled

  10. Mitigating Factors – Earthquakes and Tornadoes PV-WW Lines PV-WW #2 and PV-RD Tornadoes 1 or 2 tornadoes reported in the Valley of the Sun as a whole, i.e. a very rare event in Phoenix area Damage potential of any Valley tornado is small (F0 to F1 on Fujita tornado intensity scale) Earthquakes Maricopa County is in the lowest risk Seismic Design Category in Western U.S. Damage by earthquake to transmission towers is highly unlikely Tornadoes • 1 or 2 tornadoes reported in the Valley of the Sun as a whole, i.e. a very rare event in Phoenix area • Damage potential of any Valley tornado is small (F0 to F1 on Fujita tornado intensity scale) Earthquakes • Maricopa County is in the lowest risk Seismic Design Category in Western U.S. Damage by earthquake to transmission towers is highly unlikely

  11. Mitigating Factors – Fire Hazard PV-WW Lines PV-WW #2 and PV-RD Fire Hazard No significant threat exists Vegetation is sparse and low (10-15 feet) poses no threat in case of a range fire Fire Hazard • No significant threat exists • Vegetation is sparse and low (10-15 feet) poses no threat in case of a range fire

  12. Mitigating Factors – Fire Hazard Tallest Tree

  13. Mitigating Factors – Flood, No Snow, Nor Ice PV-WW lines PV-WW #2 and PV-RD Flood Hazard Hassayampa River January 2010 storm - high water flow within the normally dry channel. Flood waters altered the main river channel Partial reveal of foundations Exposed one of the tower foundations. The foundation was temporarily backfilled, while a more Permanent solution Currently being in Design with the cooperation of Maricopa County Flood Control and the Army Corps of Engineers. Will be implemented within the next 24 months. Snow or Ice Hazard No snow or ice hazard exists Flood Hazard • Hassayampa River • January 2010 storm - high water flow within the normally dry channel. • Flood waters altered the main river channel • Partial reveal of foundations • Exposed one of the tower foundations. • Permanent solution • Currently being in Design with the cooperation of Maricopa County Flood Control and the Army Corps of Engineers. • Will be implemented within the next 24 months. Snow or Ice Hazard • No snow or ice hazard exists

  14. Mitigating Factors – Hassayampa River

  15. Design

  16. Mitigating Factors – Tower and Insulator Design

  17. Mitigating Factors – Tower and Insulator Design

  18. Mitigating Factors – Spacer Dampers PV-WW Lines Typical spacer dampers to control conductor motion 15 years ago SRP removed numerous spacer dampers, tested them and compared performance with the new units PV-WW Line 2 and PV-RD State of the art spacer dampers to control conductor motion Used to replace typical spacers on PV-WW lines

  19. Mitigating Factors Annual Inspections and Maintenance SRP patrols twice yearly on helicopters. SRP also does a twice yearly drive of the lines, this is done to identify damaged units for replacement SRP installed bird guards where insulator contamination can be a problem. The birds are of insignificant size to cause a phase to phase fault SRP has marked shield wires in one potentially hazardous aircraft location on Interstate 10 west of the town of Buckeye with special aircraft warning balls. SRP continues to maintain these balls and proactively addresses any other maintenance issues, which result from the 4 yearly patrols

  20. Mitigating Factors – Bird Guards

  21. Mitigating Factors – Protective Relaying PV-WW 2 and PV-RD protection is provided by redundant micro processor base technology, permissive over-reaching relay schemes communicating via fiber optics and digital microwave systems on independent paths Independent dual channel transfer trip systems are provided over the redundant communication channels In addition, a third microprocessor based relay system operated in a current differential scheme is provided for backup protection. Thus scheme utilizes relay-to-relay communication over one of the redundant communication paths. The micro processor technology of this equipment incorporates self testing and monitoring capabilities for identifying critical problems, without compromising the protection of the line. PV-WW #2 and PV-RD are not equipped with single pole nor high speed reclosing relays.

  22. Mitigating Factors – Tower Failure Analysis PV-WW Line 2 Conducted by Power Engineers Inc for SRP Cause of initial failure could be a) large synoptic wind directed at conductor or tower b) very large wind gust on the tower c) developed/created weakness in the tower or its foundation Based on Extensive Analysis: The initial transverse tower failure does not strike the adjacent tower Any tower “hauled down” as secondary failures could impact the towers of other line The timing between the collapse of the tower, which does not impact adjacent line and collapse of the tower that could strike the adjacent line is 1 to 3 seconds

  23. Mitigating Factors – Tower Failure AnalysisPV-RD Line Conducted by SRP • Cause of initial failure could be a) large synoptic wind directed at conductor or tower b) very large wind gust on the tower c) developed/created weakness in the tower or its foundation Based on Extensive Analysis: • Maximum member usage is 105% in the lower portion of the tower portal and conductor bridge • The initial transverse tower failure does not strike the adjacent tower • Due to cascading failure the adjacent tower would likely sustain extensive damage only to the top of the structure. • Very low risk of cascading failure on adjacent line

  24. Mitigating Factors – Configuration of Substations As can be seen from the diagrams on the following two slides, both Rudd substation and the Palo Verde substation are breaker and a half arrangements At either substation, if there is a breaker out of maintenance, it would require both (1) a false trip on one line and (2) a stuck breaker on the other line to result in a loss of both lines because of substation configuration

  25. PV

  26. RUDD

  27. Mitigating Factors - Exposure • PV East • PV-WW #2 & PV-RD outage (N-2) • PV-WW #1 overloads at 111% • PV-East Reduced • PV-WW #1 loads to 100% for PV East at 7400MW • 2009 PV-East flow • Load Duration Curve for 2009 shows zero (0%) percent exposure • Highest Value for PV East was 7100MW < 7400MW

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