challenging transmission structure designs: case studies · 2017-11-08 · challenging transmission...
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©2017 Ulteig
Challenging Transmission Structure Designs: Case
StudiesMinnesota Power
Systems Conference
November 8, 2017
Marlon W. Vogt, PE, M. ASCE. F.SEIJosh E. Potts, PE
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MIPSYCON 2017
Your assignment, should you decide to accept…..
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Purpose
“Flying is hours and hours of boredomsprinkled with a few seconds of sheer terror.”
Gregory “Pappy” Boyington
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Why Challenging?
LandownersROW
Design ConstraintsConflicting Facilities
Regulators
Why they pay us the ‘big bucks’
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Impacts
Cost Schedule
Headaches (literally)Constructability
Aesthetics
Decisions have consequences
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Case #1 - Scenario
• Politically-charged project• 115 kV wood H-frame• Franchised for 161 kV• Upgrade to double circuit 161 kV
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Case #1 - Challenges
Same pole locationsSame pole spacing
Phase-to-Phase > 15.5 ft.
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Case #1 - Challenges
Pole bearing(OMG moments!)
Flange joints
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Case #1 - Challenges
Initial or later?
Insulator constraint
Fatigue?
Coating bleed?Vendor Involvement!
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Case #2 - Scenario
• 345kV Dead End Crossing Structure• Highly Congested Area• Single Circuit Structure, from Triple Circuit• Significant Sideslope• Grading Required
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Case #2
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Case #2
345kV Circuit
69kV Circuits
Future 345kV Line
Existing 345kV Line
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Case #3 - Scenario
• Mix of existing and new circuits• 69 kV• Public ROW• Minimum guying
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Case #3Existing Circuit #1
Underbuild(of course)
New Circuit
Existing Circuit #2
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Case #3
Loading Tree
GeometryClearances
Guying
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Case #4 - Scenario
• 138kV DC T-line• 2nd Circuit for future Wind Farm• Narrow ROW• Distribution• Landowner Requests• Circuit-Circuit clearances
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Case #4
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Case #4
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Case #5 - Scenario
• Politically-charged project
• Greenfield route
• Minimal footprint
BANANAS to NIMBY
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Case #5
Quad bundle T2
Narrow profile
LandownerAccommodations
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Case #5
Hardware
Deadends
Constructability
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Conclusion
• Challenging Designs• Creativity• Collaboration• Flexibility• Maximize what you can cram into your ROW
Many Ways to Skin a Cat
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Questions
