J. Moshtagh and R.K. Aggarwal (UK)
Conformal mapping, cable modelling, EMTP, pipe type cable
The increasing use of cable systems and the growing levels of capacity make the analysis of wave propagation to determine an accurate model for cables an important branch in Electrical Power Engineering. In particular, accurate determination of the per unit length cable series impedance Z and the 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 fault location/detection under transient fault conditions. In this respect, the EMTP is a powerful software tool for modelling the transient phenomena in power system network. However, in the modelling of underground cables, in particular the per unit length series impedance Z and the per unit length shunt admittance Y, it makes certain assumptions and approximations; this inevitably gives rise to inaccuracies when simulating the voltage and current waveforms under fault conditions. This paper presents a new approach to the modelling of the cable’s Z and Y parameters using conformal mapping (CM), which avoids the assumptions and approximations associated with the EMTP software thereby increasing the simulation accuracy. In order to make a comparison between the Z and Y parameters and in the simulated transient voltage and current signals attained via the EMTP and CM methods, a practical radial three-phase pipe type cable is analysed. The results confirm the validity and higher accuracy of the new proposed method.
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