Time Domain Modelling of Frequency Dependent Three-Phase Transmission Line Impedance

Lumped parameter computer models of transmission lines as well as Transient Network Analyzers (TNA) require the representation of the frequency dependent longitudinal impedance of a three-phase line in the form of R, L branches or Ordinary Differential Equations (ODE), respectively. The advantage of discretizing a distributed parameter line consists in the possibility of including non-linear transversal branches for corona modelling. The paper presents a Gauss-Seidel type fitting of a number of parallel R + jwL branches to each modal impedance and the building of ODEs for time domain studies.