Modeling of frequency-dependent lines and cables by means of algebra processing program

This paper proposes a new approximation method for expressing frequency-dependent effects of distributed-parameter lines by a generalized algebra-processing program. This method is applicable both to an overhead transmission system and to a cable system. There is no numerical complex calculation in the proposed as a variable of algebraic expression. The stability of the model is easily confirmed by poles of the denominator of the approximated rational function, and the order of the model is automatically determined. The accuracy of the proposed method in an overhead line and an underground cable is confirmed to be satisfactory in comparison with a field test result and calculated results obtained by a frequency transform method which gives theoretically an accurate solution including the frequency dependent effect