Abstract
Recent research work on magnetic field induction from nearby high voltage power lines to adjacent pipelines has uncovered several interesting and intriguing results under unbalanced load (steady-state) conditions of a horizontal three-phase transmission line. This paper focuses on this topic, more specifically, on the analysis of the effects of current unbalance ratio and power line configuration on the induced interference levels. Three typical transmission line configurations, two horizontal and one vertical, are examined to carry out the study. Various unbalanced currents on a phase conductor are studied to reveal the minimum interference level that can be achieved for a given right-of-way network configuration. This minimum level is caused by a cancellation effect that is introduced by a specific combination of the transmission line geometrical unbalance with respect to the pipelines and the current unbalance introduced by one of the phase conductors. The effect of the soil resistivity on the interference level is also studied under different unbalanced current conditions. It is found that the interference levels decrease with a decrease of the soil resistivity for most unbalanced current conditions. However, under some unbalanced current conditions the interference levels increase with decreasing soil resistivity. Furthermore, significant variations of soil resistivity can have practically no impact on the interference levels during other unbalanced conditions. The results obtained in this paper can be used to develop designs to minimize optimally the interference level on nearby pipelines.
