Transient analysis of multiconductor transmission lines with special reference to nonlinear problems

The paper describes the modified-Fourier-transform and modal-analysis methods used for the solution of multiconductor-line-transient problems, to show the generality of these methods in handling a wide range of switching problems. The first part of the paper deals with the extension of earlier theory in this field to the analysis of sequential-switching transients and thus to the analysis of problems in which nonlinearities, which are piecewise linear, can be dealt with. The necessary formulas for extending the earlier theories to deal with these special forms of nonlinearity are derived in an Appendix and summarised in the text. The second part of the paper is concerned with digital-computer studies of a number of examples of practical interest. These are concerned with single-circuit lines, although the theory is general and applicable to multiconductor lines with an arbitrary number of conductors, earth wires and subconductors in a bundle. The three classes of problem which are analysed numerically are as follows: sequential pole closure, trapped-charge transients and recovery-voltage transients following a short-line fault in which transient-current components are still present at the instant of circuit-breaker interruption.