Traveling Waves on Multi-Conductor Open-Wire Lines-A Numerical Yurvey of the Effects of Frequency Dependence of Modal Composition

The propagation of voltage and current on transmission lines consisting of n conductors and ground is characterized by n modes, each composed of a particular combination of voltage and current waves, traveling at a common velocity and exponentially attenuated with distance. In general the modal composition is frequency dependent. Steady-state calculations for traveling waves on four typical ac EHV lines, at from 25 to 200 miles from the source, indicate that a real, frequency-independent modal-to-phase transformation matrix (rather than an operational one) might be used for the approximate calculation of step-function response. The elements of this matrix were defined as the real parts of the exact (complex) matrix corresponding to some "effective, mid-range" frequency-5 KHz proved appropriate in the cases examined.