Frequency-dependent transmission line modeling for steady state power system harmonic analysis

This paper describes a method for modeling frequency-dependent power transmission lines. The technique presented is aimed at steady state analysis; mainly steady state harmonic studies. The Vector Fitting technique is used to determine the expression for the frequency-dependent line model. The proposed model minimizes the error arising from the constant 60 Hz parameter exact PI model. The Vector Fitting technique has previously been used to model frequency dependent transmission lines for Electromagnetic Transient (EMT) analysis. Differences between the proposed model and the EMT model are highlighted. Three-phase balanced transposed lines using falcon cable type are used as test case. The proposed model is compared to other commonly-used line models. Results show that the proposed model is significantly more accurate than the constant 60 Hz parameter exact PI model and uses lower order expressions retaining the accuracy of the EMT model.