Fault-Surge Calculations using the Phase-Domain ARMA Line Model

Abstract

For fault-surge studies, the most important and also most difficult part of the simulation is the inclusion of the frequency dependence of a transmission line, because the simulation requires a high accuracy in a wide frequency range from the power frequency to a few MHz. The authors have developed a highly efficient method for modeling a transmission line considering its complete frequency dependence, which can not be dealt with the present line models in the Electro-Magnetic Transients Program (EMTP). According to the method, a transmission line is modeled directly in the phase domain, in order to avoid the modal transformation and therefore the problems of representing its frequency dependence. The method also includes sophisticated acceleration of a transient calculation by means of an Auto-Regressive Moving Average (ARMA) model. This paper presents a steady-state initialization method of the phase-domain ARMA line model for applying it to fault-surge calculations. Calculated results agree well with rigorous frequency-domain simulations, and show improved accuracy compared with an existing frequency-dependent line model (J. Marti model) widely used as a standard model in the EMTP.