A new approach to single-phase pipe type cable modelling using conformal mapping

The increasing use of cable systems and the growing levels of capacity make the analysis of wave propagation and determining an accurate model for cables an important branch in electrical power engineering. In particular, dealing with accurate determination of the per unit length cable series impedance Z and it´s per unit length shunt admittance Y can play an important role. For example, the results of this analysis can lead to finding an accurate method for the transient state, such as fault location. The EMTP as a powerful software tool in the transient state obtains Z and Y on the basis of certain assumptions and approximations being made. This paper presents a new method using conformal mapping (CM) in order to modify impedance and admittance per unit length in a single-phase pipe type cable in EMTP. With this approach, both the constant-frequency and frequency-dependent parameters have been studied. In order to have a comparison between Z and Y in EMTP and CM methods, a practical radial single-phase pipe type cable is analysed. The result´s confirm the validity and higher accuracy of the new proposed method.