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postgraduate thesis: Field analysis in power supply lines by integral equation method
Title  Field analysis in power supply lines by integral equation method 

Authors  
Issue Date  1974 
Publisher  The University of Hong Kong (Pokfulam, Hong Kong) 
Citation  Foo, P. [傅必雨]. (1974). Field analysis in power supply lines by integral equation method. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. 
Abstract  (Uncorrected OCR)
Abstract of thesis entitled
liField analysis in power supply lines by integraJ. equation methodll
subm1 tted by FOe, PIK YlJE for the degree of Ph.D
at the University of Hong Kong in December, 1974.
Abstract
In this thesis, the integral equation (I.E.) method has been employed successfully to solve field problems in power supply lines. Though the I.E. method is mathematically quite involved, it is shown that it is possible to treat the integral equation as a system of linear equations. Hence the transformed simultaneous linear equations can be considered as the starting point for solving problems either in overhead
lines or \Ulderground power cables.
In overhead lines, especially in ExtraHighVoltage and Ultra
HighVoltage systems, an evaluation of the electric field near each conductor, especially the maximum electric field, is essential as corona and radio interference become important considerations in the design of such lines. The I.E. method has many advantages over the other existing methods in calculating the potential gradient at the surface of the overhead lines in that it yieldS reasonably accurate results with comparatively simple numerical computations. The difference between the present method and the existing methods is the basic assumption.
In the I.E. method, subconductor surfaces are treated as equipotential lines whereas in other existing methods, the subconductor surfaces usually do not coincide with the simulated equipotential lines. The method can also be applied equally well to symmetrical or asymmetrical bundle conductors with or without ground wires. Other parameters such as capacitances, potential gradients at the earth surface etc. are also
included in the computer program.
In underground cable systems, the I. E. method proves to be very
effective in tackling the thermal field problem, especially when the cables are buried shallow and thus the earth i s surface can no longer be
treated as isothermal. .It has been found that the thermal resistance (external) obtained wi::;h a nonisothermal earth surface is considerably higher than that obtained under the assuumption of an isothermal earth surface. With non.isothermal earth surface, the temperature difference on the earth surface between the spot vertically above the cable and the spot at a distance eClual to twice the depth of burial of the cable away could be as high as lOoe. The finitedifference or fini te搪lement method could likewise be used to solve the problem of a nonisothermal ea>:>th surface, but the computer storage re'luired and the execution time would be much more than that using the I.E. method. 
Degree  Doctor of Philosophy 
Subject  Electric lines  Overhead. Underground electric lines. Electric power distribution  Mathematical models. Integral equations. 
Dept/Program  Electrical and Electronic Engineering 
Persistent Identifier  http://hdl.handle.net/10722/27434 
HKU Library Item ID  b1227824 
DC Field  Value  Language 

dc.contributor.author  Foo, Pikyue   
dc.contributor.author  傅必雨  zh_HK 
dc.date.issued  1974   
dc.identifier.citation  Foo, P. [傅必雨]. (1974). Field analysis in power supply lines by integral equation method. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR.   
dc.identifier.uri  http://hdl.handle.net/10722/27434   
dc.description.abstract  (Uncorrected OCR) Abstract of thesis entitled liField analysis in power supply lines by integraJ. equation methodll subm1 tted by FOe, PIK YlJE for the degree of Ph.D at the University of Hong Kong in December, 1974. Abstract In this thesis, the integral equation (I.E.) method has been employed successfully to solve field problems in power supply lines. Though the I.E. method is mathematically quite involved, it is shown that it is possible to treat the integral equation as a system of linear equations. Hence the transformed simultaneous linear equations can be considered as the starting point for solving problems either in overhead lines or \Ulderground power cables. In overhead lines, especially in ExtraHighVoltage and Ultra HighVoltage systems, an evaluation of the electric field near each conductor, especially the maximum electric field, is essential as corona and radio interference become important considerations in the design of such lines. The I.E. method has many advantages over the other existing methods in calculating the potential gradient at the surface of the overhead lines in that it yieldS reasonably accurate results with comparatively simple numerical computations. The difference between the present method and the existing methods is the basic assumption. In the I.E. method, subconductor surfaces are treated as equipotential lines whereas in other existing methods, the subconductor surfaces usually do not coincide with the simulated equipotential lines. The method can also be applied equally well to symmetrical or asymmetrical bundle conductors with or without ground wires. Other parameters such as capacitances, potential gradients at the earth surface etc. are also included in the computer program. In underground cable systems, the I. E. method proves to be very effective in tackling the thermal field problem, especially when the cables are buried shallow and thus the earth i s surface can no longer be treated as isothermal. .It has been found that the thermal resistance (external) obtained wi::;h a nonisothermal earth surface is considerably higher than that obtained under the assuumption of an isothermal earth surface. With non.isothermal earth surface, the temperature difference on the earth surface between the spot vertically above the cable and the spot at a distance eClual to twice the depth of burial of the cable away could be as high as lOoe. The finitedifference or fini te搪lement method could likewise be used to solve the problem of a nonisothermal ea>:>th surface, but the computer storage re'luired and the execution time would be much more than that using the I.E. method.  zh_HK 
dc.language  eng   
dc.publisher  The University of Hong Kong (Pokfulam, Hong Kong)   
dc.relation.ispartof  HKU Theses Online (HKUTO)   
dc.rights  The author retains all proprietary rights, (such as patent rights) and the right to use in future works.   
dc.source.uri  http://hub.hku.hk/bib/B12278245   
dc.subject.lcsh  Electric lines  Overhead.   
dc.subject.lcsh  Underground electric lines.   
dc.subject.lcsh  Electric power distribution  Mathematical models.   
dc.subject.lcsh  Integral equations.   
dc.title  Field analysis in power supply lines by integral equation method   
dc.type  PG_Thesis   
dc.identifier.hkul  b1227824   
dc.description.thesisname  Doctor of Philosophy   
dc.description.thesislevel  Doctoral   
dc.description.thesisdiscipline  Electrical and Electronic Engineering   
dc.description.nature  abstract   
dc.description.nature  toc   