Mode domain multiphase transmission line model-use in transient studies

This paper presents a new model te represent multiphase transmission lines in transient studies, including the frequency dependence of longitudinal parameters. The mndel iises the exact modes, fnr ideally transposed lines, and "quasi-modesʹʹ for non-transpcaed lines. For the latter it is necessary to have a vertical symmetry plane. The frequency dependence is represented with synthetic circuits, with one ITcircuit fnr each mode. The transf~~rmatimmi atrix used for the entire frequency range is tlie Clarkeʹs (me ant1 as it is a real matrix it is modeled through ideal transformers. The model is described for three-phase lines and double three-phase lines. An application nf the metlioclology is presented for a 440 kV single three-phase transmission line where it is macle mecle analysis, statistical energimtion and frequency scan analysis. The simulations are performed in EMTP with the preposed model and with a freqiiency dependent EMTP line model, the Semlyen one, supposing the line transposed and liontransposed.