State Equation Modelling Of Untranposed Three Phase Lines

Powerful simulation programs are available for large electric and electronic circuits with lumped parameter elements. State equation models are used for each component. This paper presents the methodology for obtaining a finite order state equation model for transmission lines, despite the distributed nature of their parameters. The lines considered- are three-phase, untransposed, with full representation of frequency- dependence. There is no requirement for constant (real) transformation atrices. All calculations are initially performed in the s-domain. The results are in the form of standard state equations with phase voltages at both line ends as inputs and corresponding currents as outputs. These equations can then be interfaced with those of linear or non-linear connected components and integrated numerically using advanced numerical integration methods.