Direct frequency domain computation of transmission line transients due to switching operations

Realistic transmission lines are most easily repre sented directly in the frequency domain. For the computation of single switching operations to be started off in the frequency do main, switches have traditionally been modelled through the use of compensatory voltage/current sources. The practical computation of the complete transient response involves the calculation of the response for each switching operation for the whole observation time; sequentially, all of the individual responses are added up. This paper presents a novel frequency-domain-based methodology for calculating in a straightforward manner the transient response of transmission lines/underground cables due to switching operations. The core of the proposed methodology consists in using a fast Fourier transform-generated switching matrix where the on/off times are included. The computational stability of the transient response has been assured via the numerical Laplace transform which is free of the well-known numerical errors incurred by the direct use of a discrete Fourier transform.