cigre experimentalconductormodels-ml.pdf
TRANSCRIPT
Experimental Conductor Modeling
Mark A. Lancaster, P.E. Director of Overhead Transmission Engineering
SC-B2 Bled, Slovenia May 30, 2012
Overview
• Experimental conductor modeling
• Thermal Elongation modeling
• Elongation modeling methods
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Conductor Elongation
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Elongation Modeling Methods
• Experimental Plastic Elongation model (EPE)
• Simplified Plastic Elongation model (SPE)
• Linear Elongation model (LE)
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Elongation Modeling Methods
Linear Elongation model (LE)
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Models the conductor as a linear spring with an effective elastic modulus and an effective coefficient of thermal elongation
Elongation Modeling Methods
Simplified Plastic Elongation model (SPE)
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Models the conductor as a linear spring. Plastic elongation added as a temperature offset based on experience.
Elongation Modeling Methods
Experimental Plastic Elongation model (EPE)
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• Conductors are modeled as non-linear springs that elongate elastically as a function of tension, plastically as a function of tension and time, and thermally as a function of temperature.
• The elongation of each component (e.g. steel and aluminum) is calculated separately.
• Plastic elongation of the conductor due to “settling”, “creep elongation”, and “permanent elongation due to high tension loads” is calculated for an assumed series of loading events over the life of the line.
Overview
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• Experimental conductor modeling
• Experimental Mechanical modeling
• Thermal Elongation modeling
Elongation modeling methods
Linear Thermal Elongation
Coefficients of Linear Thermal Expansion
1350 Aluminum 12.8 x 10-6 23.0 x 10-6
Steel 6.4 x 10-6 11.5 x 10-6
Per °F Per °C
Aluminum elongates at twice the rate of steel
3M ACCR Core 3.5 x 10-6 6.3 x 10-6
3M core elongates at ~ ½ the rate of steel
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Thermal Elongation
When Heated When Cooled
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Limiting Factors
HTLS ACSR
Same Initial Sag
@ 20°C
200°C 200°C
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Overview
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• Experimental conductor modeling
Thermal Elongation modeling
Elongation modeling methods
Sag and Tension Simplified (No Temperature or Creep) Response Example:
Addition Stretch from Loads
Steel Core Curve
Installed Tension
First Load Event
Second Load Event
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Sag and Tension
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Sag and Tension
Span Length
Diameter Weight RBS
Weight
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NEW ASTM Standards
• Would like support to update standard test methods and accommodate improvements in testing and measurement technology • Shorter test beds • 500 hour vs. 1000 hour creep test.
• Attempting to harmonize AA, CSA and IEC
• New stress strain and creep standards based on old Aluminum Association (AA) methods
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Questions
Questions?
Copyright 2011 Southwire Company. All Rights Reserved.
References: • Southwire Overhead Conductor Manual, 2nd Edition • CIGRE SCB2/TF B2.12.3, “Calculation of Sag-tension for Overhead Power
Lines”, Technical Brochure 324, 2007