Evaluation of FDTD Model for Transient Studies with Complicated Cable Configurations

The increasing integration of underground power cables in the transmission network gives rise to technical challenges, especially concerning electromagnetic transients (e.g. resonances). In order to study transient phenomena, accurate simulation models should be built where the chosen modeling detail of the cable configuration is of utmost importance. In some cases the well-established Universal Line Model (ULM) shows stability problems due to passivity violations. In this paper the ULM is compared with a Finite-Difference Time Domain (FDTD) model in terms of accuracy, computational performance and stability. Simulation results show that with comparable accuracy the FDTD model present improved stability but with higher computational burden. Moreover, a sensitivity analysis for the FDTD model is performed to check how the chosen time-step affects the resulting waveforms and it is evident that for larger time step deviations in both the maximum overvoltage and the oscillation frequency are present.