Comparison of the fdLine and ULM Frequency Dependent EMTP Line Models with a Reference Laplace Solution

-This paper presents time-domain simulation results obtained with the frequency-dependence fdLine and ULM line models in the EMTP for a variety of asymmetrical line configurations, including single-circuit, double-circuit and parallel lines. The results are compared with a reference frequency-domain solution based on the Laplace transform. The comparisons include open and short circuit conditions during the transient and steady-state periods. As observed from the simulations, both fdLine and ULM follow very closely the results obtained with the Laplace solution. This is in contrast with the traditional belief that fdLine does not give accurate results for asymmetrical line configurations.