Analysis of the Propagation Characteristics of Single-Core Cables from Experimental Results using Modal Decomposition

In this paper various field test transient responses from a medium-voltage single-core cable lying on the ground surface are presented. The results from six different excitation cases are compared, applying the modal decomposition theory with the use of a complex-frequency-dependent modal transformation matrix. The resulting modal voltages present unique modal travel time and attenuation, leading to significant remarks about the wave propagation along the cable in each examined case. The decoupled voltages are also compared to the corresponding obtained from the assumption of a real-constant transformation matrix. Results are in good agreement, validating the use of the simplified modal transformation matrix for the calculation of high-frequency transient phenomena in single-phase cables with short lengths. The calculated propagation modes are eventually related with the voltage differences and potentials of the examined cable, revealing their significance in the study of various engineering applications.