Effect of Temperature Variations on Wave Propagation Characteristics in Power Cables

Thermal Distortion of Signal Propagation Modes Due to Dynamic Loading in Medium-Voltage Cables

“…With second-order perturbation (dotted curves), equal results are obtained as from directly evaluating the ZY matrices. Appendix B shows that the eigenvector elements remain close to the ones in (6). The average temperature of the insulation around the phase carrying the largest current was around 95 °C.…”

“…Dielectric losses also contribute. The matrix components hardly deviate from the theoretical ones in (6), despite the applied unbalanced currents. A maximum frequency of 50 MHz is employed, needed for sufficient resolution in the time domain (corresponding time steps are 20 ns).…”

“…13, x FOR PEER REVIEW 9 of 17 evaluating the ZY matrices. Appendix B shows that the eigenvector elements remain close to the ones in(6).…”

“…A commonly employed insulation material for medium-voltage cables is XLPE (cross-linked polyethylene). The literature on single-phase XLPE cables shows a non-linear increase in the propagation velocity with increasing temperature [4][5][6]. These results are obtained either by time-domain reflectometry (TDR) on a cable section or by analysis of the dielectric material using a vector network analyzer (VNA).…”

“…This (unusual) condition is taken to enforce a relatively large temperature gradient throughout the cable cross-section to demonstrate the effect on the propagation coefficients. Details of the simulation are provided in Appendix B. Propagation velocity and attenuation are depicted as functions of frequency, which are ordered according to the corresponding eigenvectors in (6). For a balanced load (blue curves), the phase velocity of the first mode is significantly lower, with slightly increased attenuation compared to the others.…”