Modelling of single-phase nonuniform transmission lines in electromagnetic transient simulations

An exponential single-phase line model is introduced to represent nonuniform transmission lines. When the line parameters are assumed to vary exponentially, a set of two-port equations can be formed in the frequency domain, which contain frequency-dependent functions. These functions are then synthesized with rational functions of the minimum-phase-shift type. Utilizing a fast recursive convolution technique, the time-domain equations of the proposed model reduce to a form similar to those in Bergeron´s method. Plus, the model is compatible with general electromagnetic transients programs such as the EMTP. Time-domain simulations with the proposed model show good agreement with published experimental results, and with those produced by a cascade multi-section model where the line is divided into many short sections of uniform transmission lines