Overhead transmission lines impacts on neighboring buried metallic gas pipelines

Abstract

Buried metallic pipelines are used to transmit the services such as natural gas and petroleum products to the citizens. Sometimes these pipelines are constructed in the same pathway of the overhead transmission lines to save the additional right-of-way cost, and to avoid the destruction of agricultural lands. AC voltage is induced on these pipelines by the power line electric and magnetic fields. There are many mechanisms that describe the AC voltage inducing on these pipelines; capacitive coupling describes the pipelines induced voltage by the power lines electric field, inductive coupling characterizes the induced voltage caused by the OHTLs electromagnetic fields and conductive coupling is created in buried pipelines near to OHTLs by earth fault current. In the present paper, the induced voltages of pipelines created by overhead transmission lines due to the different couplings are investigated in normal condition of operation as well as line to ground fault. The current of the coating discharging and AC corrosion is investigated. The induced overvoltage appearing on the natural gas pipeline is measured in steady-state condition of the transmission circuits operation. Proposed mitigation technique for induced voltage based on earthing polarization cells is presented and investigated. Moreover, the paper studied the influence of applying different configurations of the proposed technique on the AC induced voltage.