Direct phase-domain modelling of frequency-dependent overhead transmission lines

A new wideband transmission line model, based on synthesizing the line functions directly in the phase domain, is presented. It includes the complete frequency-dependent nature of untransposed overhead transmission lines by means of recursive convolutions over a wide frequency range. The model belongs to the class of time-domain models and is designed to be implemented in general electromagnetic transients programs such as the EMTP. Because the synthesis of the frequency-dependent modal transformation matrix is avoided, the method requires fewer convolutions at each time step than full frequency-dependent modal-domain models. Simulations have been performed comparing the proposed model with existing line models, with field recordings, and with calculations from a frequency-domain program. The new model provides accurate answers in both steady-state and transient conditions