Modeling nonuniform transmission lines for time domain simulation of electromagnetic transients

Transmission lines with nonparallel conductors or significant sags and vertical structures, such as towers, can be viewed and modeled as nonuniform lines (NULs). The parameters of NULs are distance dependent. This paper presents a mathematical model for time domain simulation of electromagnetic transients in multiphase NULs taking into account the frequency dependence of the parameters. The model is based on the traveling wave phenomenon and accommodates any NUL geometry. In addition, the model can be interfaced with time domain programs such as the EMTP. The proposed methodology is validated by comparing the results with those obtained from a frequency domain model using the numerical Laplace transform (LT), the method of characteristics (MC), and also with test results reported by other investigators.