Phase domain modeling of frequency-dependent transmission lines by means of an ARMA model

This paper presents a method for time-domain transient calculation in which frequency-dependent transmission lines and cables are modeled in the phase domain rather than in the modal domain. This avoids convolution due to the modal transformation, and possible numerical instability due to mode crossing. In the new approach, time domain convolutions are replaced by an ARMA (Auto-Regressive Moving Average) model that minimizes computation and is EMTP-compatible. A fast and stable method to produce the ARMA model is developed, and results are shown to agree well with both rigorous frequency-domain simulations and also field tests.