challenging transmission structure designs: case studies · 2017-11-08 · challenging transmission...

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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

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Thank You!

marlon.vogt@ulteig.comjosh.potts@ulteig.com