Accurate Computation of Transient Profiles Along Multiconductor Transmission Systems by Means of the Numerical Laplace Transform

In this paper, transient internal profiles along multiconductor transmission lines are obtained from a model described in the q- s domain (spatial frequency-temporal frequency). In such domain, the telegrapher equations of the line are defined in a direct algebraic form. Applying boundary conditions, these equations can be easily solved for V (q,s) and I (q,s). Then, the inverse numerical Laplace transform is applied successively (twice) to obtain v (z,t) and i (z,t), that is, the voltage and current profiles along the line. Besides, since the line's electrical parameters are defined in the frequency domain, the frequency dependence of such parameters is included in a straightforward manner. Test cases corresponding to an overhead line, a transformer winding, an underground power cable, and a transmission network are evaluated in order to demonstrate the accuracy and versatility of the proposed method. The results are compared with those obtained with Alternative Transients Program/Electromagnetic Transients Program and PSCAD/EMTDC at specific points along the transmission systems under analysis, given that the space discretization is cumbersome and prone to error accumulation in these time-domain simulation programs.