Partitioned-Time Transient Simulation via a Hybrid Time–Frequency Domain Methodology

This paper presents a hybrid time-frequency domain methodology to calculate midfrequency transients of an electrical network that includes transmission lines (TLs) and considering that the simulation is carried out on a partitioned-time basis. Basically, the line is modeled as a two-port element and the network simulation is performed in the frequency domain for each time subinterval. The transition between subintervals is made by calculating an equivalent current source for each end of the line. These sources represent the initial conditions for a subsequent subinterval, and their calculation is based on a rational approximation of the two-port line parameters. The conversion of frequency-domain variables to the time domain is efficiently performed through numerical Laplace transform operations. A sequential closure of a three-phase TL is presented for illustration of the proposed methodology.