Resonance in inhomogeneous transmission lines using travelling waves

The paper presents an analytical procedure for estimation of resonance frequencies in inhomogeneous transmission lines. The procedure is based on a new approach which is based on the fact that the phenomenon is characterized by an algebraic sum of travelling current waves at the beginning of the line. Two typical cases of discontinuities on a practical transmission line are considered: a transposed line and a long distant radial transmission line with static VAr compensation. By applying the presented analytical procedure, it is possible to identify the conditions for the appearance of subsynchronous resonant frequencies on long distant radial transmission lines with static VAr compensation without computers. Besides simpler and faster solving of the problem, the obtained analytical expressions offer more direct insight into the physical essence of the phenomena.