Impact of the Transformer Stray Capacitances on the Ground Mode Current in Unearthed OHL Networks: Analysis of the Travelling Waves Propagation

This paper focuses on the ground mode current behaviour in unearthed operated overhead line networks. In particular, it aims at investigating which is the impact of the transformer stray capacitances on the current travelling wave propagation along the line, in terms of propagation velocity and arrival times to the measurement terminal. The importance of this study lies in the fact that several travelling waves-based fault location approaches presented in literature exploit the ground mode current to identify the fault position. Hence, in order to develop or to improve such methods, it is helpful to comprehend the impact that the transformer stray capacitances have on the travelling wave propagation. Moreover, it is also useful to understand which should be the detail level in modelling the transformer stray capacitances in order to correctly represent the travelling wave propagation in a simulation environment. The paper demonstrates that a different modelling of the stray capacitances could imply different velocities of the travelling wave propagation.