VARIATION IN PHASE SHIFT OF MULTI-CIRCUITS HVTLS PHASE CONDUCTOR ARRANGEMENTS ON THE INDUCED VOLTAGE ON BURIED PIPELINE: A THEORETICAL STUDY

Alternating current interference from power transmission lines on nearby metallic pipelines has been a topic of research in the past years. Of particular interest is the induced voltage on metallic pipelines due to the time varying electromagnetic fields coupling from the transmission lines. Several related studies dealing with this problem have been published. Nevertheless, the issue of current phase shift variation and its effect on the voltage induced on metallic pipelines has not been fully covered yet. In view of this, we present the computation of the induced open circuit voltage on a buried metallic pipeline running in parallel with the power transmission lines in three Rand Water sites, South Africa. The computation was performed using Carson’s relations and power system concepts of mutual impedances between two circuits. The variation in current phase shift was considered for six different phase conductor arrangements. The overall simulation results yield useful information. The computations show that the induced open circuit voltage changes significantly with different phase arrangements and with variations in the current phase shift between the two circuits. In this work, the characteristic nature of the variation in the induced open circuit voltage for the six phase arrangements and phase shifts are examined in more detail. We concluded that in placing buried pipelines in the vicinity of AC double-circuits power lines, it is essential to consider the phase arrangement of the line and current phase shift between the two circuits. These, together with other line parameters, are vital in evaluating the induced voltage with the pipe position before installation and for the design of effective AC mitigation techniques.