Overhead Power Lines

The basic elements of overhead power line technology have been known for many years. However, this technology has continuously developed, for example, adjusting the design of the lines to new transmission needs and to available rights-of-way, and to accommodate environmental concerns or resources. Since many existing overhead line installations are approaching the end of their economic and technical lifetime, strategies for maintenance to extending their operational life are needed. Also, because of the introduction of new standards and deregulation, the basis of design and verification for all aspects and steps in overhead line planning and construction has changed. The industry, therefore, requires a publication reflecting these developments and changes. Overhead Power Lines present not only the scientific and engineering basis for the electric and mechanical design, but also comprehensively describe all aspects of most recent technology, including the selection and design of components such as conductors, insulators, fittings, supports and foundations. The chapters on line survey, construction and maintenance address updated requirements and solutions. In addition, the book carefully considers the changing economic and technical environment of the overhead power line business. This publication is intended to introduce students and beginners to the full range of relevant topics of line design and implementation, and to serve as a valuable reference to engineers and technicians employed by overhead line operators, contractors and consulting companies to carry out their daily tasks. The book also supplies everyone else in the electric-energy supply industry, including design, maintenance, and construction engineers, with a ready reference. This first English-language edition is based on the 5th German-language edition and incorporates the latest international standards sponsored by Cigré, the International Council of Large Electric Systems, IECand CENELEC. The authors are recognized experts who have long participated in, and actively contributed, to Cigré.

Klappentext

The only book containing a complete treatment on the construction of electric power lines. Reflecting the changing economic and technical environment of the industry, this publication introduces beginners to the full range of relevant topics of line design and implementation.

Inhalt

1 Overall planning.- 1.0 Symbols.- 1.1 Development stages of a transmission project.- 1.2 Transmission planning.- 1.2.1 Objective.- 1.2.2 Planning stages.- 1.2.3 Planning aspects regarding transmission lines.- 1.3 Planning methods.- 1.3.1 Data acquisition and preparation.- 1.3.2 Formulation and preselection of alternatives.- 1.3.3 Electrical studies.- 1.3.4 Economic studies and final evaluation.- 1.4 Planning criteria.- 1.4.1 General.- 1.4.2 Criteria for steady-state conditions.- 1.4.3 Criteria for temporary and transient conditions.- 1.5 Evolution and selection of voltage levels.- 1.5.1 Evolution of transmission voltages.- 1.5.2 Introduction of transmission voltages.- 1.6 Conductor selection.- 1.7 Selection of line configuration.- 1.8 Direct current transmission.- 1.8.1 Aspects of DC transmission components.- 1.8.2 Economic comparison of DC and AC lines.- 1.8.3 Technical comparison of AC and DC transmission.- 1.8.4 Practical use of DC transmission.- 1.9 Transmission with higher order phase lines.- 1.9.1 Options.- 1.9.2 Properties of multiple-phase systems.- 1.9.3 Present experience.- 1.10 Investments.- 1.11 Licences and permit procedures.- 1.12 Underground transmission versus overhead lines.- 1.12.1 Application and planning aspects.- 1.12.2 Environmental constraints.- 1.12.3 Technical limitations.- 1.12.4 Comparative investments.- 1.12.5 Perspectives.- 1.13 Results of overall planning.- 1.14 References.- 2 Electric requirements and design.- 2.0 Symbols.- 2.1 Overhead lines as components of electric systems.- 2.1.1 Surge impedance and surge impedance load (natural power).- 2.1.2 Stability.- 2.1.3 Voltage regulation and maximum permissible losses.- 2.1.4 Capability of a line.- 2.1.5 Reliability and availability.- 2.1.6 Reactive power compensation.- 2.1.7 Power transmitted versus right-of-way width.- 2.2 Current-related phenomena.- 2.2.1 Normal and emergency conditions.- 2.2.2 Ohmic losses.- 2.2.3 Short circuit condition.- 2.3 Voltage and current-related phenomena.- 2.3.1 Introduction.- 2.3.2 Electrical and magnetic fields.- 2.3.3 Corona phenomena and related effects.- 2.3.4 Audible noise (AN).- 2.3.5 Impact of line design on voltage- and current-depending phenomena.- 2.4 Line performance and insulation requirements.- 2.4.1 Introduction.- 2.4.2 Power frequency voltages and temporary overvoltages.- 2.4.3 Slow-front overvoltages.- 2.4.4 Fast-front overvoltages.- 2.4.5 Principles of insulation coordination..- 2.4.6 Live-line maintenance.- 2.5 Clearances.- 2.5.1 Clearance requirements.- 2.5.2 Internal and external clearances.- 2.6 References.- 3 Electric parameters.- 3.0 Symbols.- 3.1 Introduction.- 3.2 Resistance.- 3.3 Positive-sequence impedance.- 3.3.1 Introduction.- 3.3.2 Inductance and inductive Reactance.- 3.4 Zero-sequence impedance.- 3.4.1 Introduction.- 3.4.2 Simplified approach for the determination of zero-sequence impedances.- 3.5 Capacitance and capacitive reactance.- 3.5.1 General considerations.- 3.5.2 Single-circuit lines.- 3.5.3 Double-circuit lines.- 3.6 Admittance.- 3.7 Electric representation of lines.- 3.7.1 Goals and basic conditions.- 3.7.2 Short- and medium-length lines.- 3.7.3 Long-length transmission lines..- 3.8 References.- 4 Lightning protection.- 4.0 Symbols.- 4.1 Significance of lightning.- 4.2 Formation of lightning strokes.- 4.2.1 Mechanism of lightning discharge.- 4.2.2 Impulse behaviour of lightning discharges.- 4.2.3 Electric characteristics of the discharges.- 4.3 Frequency and intensity of lightning strokes.- 4.3.1 Keraunic levels and earth flash density.- 4.3.2 Magnitude of lightning stroke currents.- 4.3.3 Direct and indirect lightning strokes.- 4.4 Arrangement and efficiency of earth wires.- 4.4.1 Theoretical background.- 4.4.2 Effective shielding by earth wires.- 4.4.3 Surge arresters.- 4.4.4 Assessment of lightning performance of overhead lines.- 4.5 Earthing in view of lightning protection.- 4.5.1 Significance of earthing for lightning protection.- 4.5.2 Surge impedance of earthing systems.- 4.6 References.- 5 Earthing.- 5.0 Symbols.- 5.1 Purpose of earthing.- 5.2 Definitions and basic principles.- 5.3 Requirements.- 5.3.1 Standards.- 5.3.2 Safety of persons.- 5.3.3 Thermal short-circuit strength.- 5.3.4 Mechanical strength and corrosion resistance.- 5.3.5 Currents to be considered.- 5.4 Earthing for personal safety purposes.- 5.5 Operational earthing.- 5.6 Lightning protection earthing.- 5.7 Rating for short-term currents.- 5.8 Soil resistivity and conductivity.- 5.9 Calculation of earthing resistance.- 5.9.1 Spherical electrode.- 5.9.2 Earthing rods.- 5.9.3 Horizontally arranged electrode wires (counterpoises).- 5.10 Measurements of soil resistivity.- 5.10.1 Basic principles.- 5.10.2 Measuring methods.- 5.11 Measurement of earthing resistance.- 5.12 Earthing resistance in non-homogeneous soils.- 5.12.1 Soil resistivity in a two-layer soil structure.- 5.12.2 Computation of earthing resistance in a two-layer soil structure.- 5.12.3 Computation of earthing resistance by means of the apparent resistivity.- 5.12.4 Computation of earthing resistance of three-dimensional structures.- 5.12.5 Example for computation of earthing resistance.- 5.13 Practical rules for installation of earthing systems.- 5.13.1 Radial and ring-type earthing counterpoises.- 5.13.2 Vertically or obliquely driven earthing rods.- 5.13.3 Bonding between earthing electrodes.- 5.13.4 Earthing connections.- 5.14 References.- 6 Requirements on loading and strength.- 6.0 Symbols.- 6.1 Mechanical design of the overhead line system.- 6.1.1 Components and elements of an over…