Summary
Overhead lines age naturally or may reach premature end-of-life. Motivations for rebuilding or refurbishing lines have included reliability (poor lightning performance), thermal rating, component end-of-life, reduced visual impact and right-of-way encroachment (grounding). The Brochure adds value to redesign projects, promoting synergies among disciplines and developing alternatives that improve, or at least do not degrade, lightning performance while satisfying other objectives.
Table of content
1. Introduction
1.1. Background and Context to Scope
1.2. Terms of Reference
1.3. Motivations of Typical Rebuilding and Refurbishing Projects
1.4. Scope of Recent Rebuilding and Refurbishing Projects
1.5. Structure of Technical Brochure
2. Global Lightning Environment
2.1. Lightning Ground Flash Density, Ng
2.2. Lightning Return Stroke (RS) Peak Current
2.3. Estimates of Rise Time (and relation to Soil Resistivity)
2.4. Statistical Distribution of Lightning Parameters
2.5. Effects of Terrain and Altitude on Lightning Parameters
2.6. Anticipated Effects of Climate Change on Lightning Parameters
3. Global Grounding Environment
3.1. Soil Resistivity Estimates from Radio Wave Propagation
3.2. Geotechnology for Electrical Parameters of Soil
3.3. Soil Clay / Sand / Silt Fractions
3.4. Soil Moisture Content and Seasonal Variation
3.5. Depth to Bedrock (DTB) of Surface Layers
3.6. Statistical Distribution of Grounding Parameters
3.7. Anticipated Effects of Climate Change on Grounding Environment
4. Global Corrosion, Contamination and Wind Environment
4.1. Factors in Above-Grade Corrosion
4.2. Factors in Below-Grade Corrosion
4.3. Factors in Pollution of Insulators
4.4. Factors in Wind Forces
4.5. Statistical Distribution of Environmental Factors
4.6. Anticipated Effects of Climate Change on Environmental Factors
5. Typical Options in Overhead Line Rebuilding and Refurbishing Projects
5.1. Transmission "Needs Studies"
5.2. Overhead Groundwire Installation or Replacement
5.3. Phase Conductor Replacement
5.4. Insulator Replacement or Remediation
5.5. Line Surge Arrester (LSA) Installation
5.6. Remediation of Grounding Systems
5.7. Structure Reinforcement or Replacement
5.8. Line Compaction
6. Case Studies: AC System Voltage < 100 kV
6.1. Bangkok, Thailand: Improved Grounding on Shielded 24 kV Distribution Lines
6.2. New South Wales, Australia: 33 kV steel pole uprating with DC-blocking line surge arrester
6.3. France: Application of 63 kV and 90 kV EGLA
8. Case Studies – AC System Voltage > 220 kV
8.1. Newfoundland, Canada: Apply NGLA on 230 kV Unshielded Line
8.2. United Kingdom: Upgrading 275 kV Line using CICA and 400 kV Line using T-Pylons
8.3. Poland: Rebuild 400 kV Single Circuit to Double Circuit
8.4. Russia/Finland: Apply NGLA on 400 kV Double Circuit Line
8.5. Romania: Apply NGLA on 400 kV Line with Ice Damage to OHGW
9. Case Studies – HVDC Systems
9.1. EU: Repurpose 16.7Hz 55 kV AC System to 78 or 156 kV DC
9.2. Minnesota, USA: Rebuilding 250 kV DC Link
9.3. Manitoba, Canada: Rebuilding 450 kV DC Link
9.4. Seoul, Korea: Rebuild Double Circuit 765 kV AC to Double 500 kV DC
10. Conclusion
Appendix A. Definitions, Terms and Abbreviations
A.1. General Terms
A.2. Organizational Acronyms
A.3. Specific Terms in this TB
A.4. Symbols in this TB
Appendix B. Links and References
B.1. Standards
B.2. CIGRE Papers and Contributions
B.3. References
Appendix C. Equivalent Resistivity of Layered Soil
C.1. Thin Layer of Surface Soil
C.2. Flat Electrode on or in Surface Layer of Two-Layer Soil
C.3. Cylinder in Two-Layer Soil
C.4. Two Cylinders in Bottom Layer of Two-Layer Soil
Appendix D. Calculation of Coupling Coefficients for Overhead Lines with Multiple Shield Wires
D.1. Geometric Surge Impedance Coupling Coefficients
D.2. Surge Impedance Matrix in Spreadsheet
D.3. Calculation of Coupling Coefficients with Single OHGW
D.4. Calculation of Coupling Coefficients with OHGW and Six UBGW
D.5. Coupling Coefficient Evaluation incorporating Corona Effects
D.6. Corona Effects in Air and Limiting Gradient in Soil Ionization
D.7. Draft Document Information
Additional informations
| Publication type | Technical Brochures |
|---|---|
| Reference | 979 |
| Publication year | |
| Publisher | CIGRE |
| ISBN | 978-2-85873-684-3 |
| Study committees |
|
| Working groups | JWG B2/C4.76 |
| File size | 22 MB |
| Pages number | 285 |
| Price for non member | 300 € |
| Price for member | Free |
Authors
W.A. CHISHOLM, Convenor, F.H. SILVEIRA, Secretary
R. ALVAREZ (PE), M. ARAÚJO (BR), S. ASSIS (BR), S. ASTO (PE), B. BESKE (US), J. BODENSCHATZ (US), A. COSIC (SE), A. CRUZ (BR), L. DIAZ (FR), F. GIRAUDET (DE), N. HUDI (MY), K. LENARCZYK (PL), A. MANMOHAN (CA), J. MCCORMACK (AU), K. MICHISHITA (JP), T. MIKI (JP), P. NORBERG (SE), K. REICH (AT), L. SCHWALT (AT), M. DE SOUZA (BR), G. STAPLETON (AU), I. TANNEMAAT (NL), M. TASÇI (TR), C. WANG (CA), A. WILLIAMS (AU), S. XIE (CN), G. YEHEZKEL (IL), C. ZACHARIADES (UK)
Keywords
Electric power system, overhead line, lightning, grounding, reliability, soil resistivity, insulation, surge impedance coupling
