Mitigation of the produced voltages in AC overhead power-lines/pipelines parallelism during power frequency and lightning conditions

This paper presents a theoretical simulation for a pipeline running in parallel to AC overhead power lines using the 'CONCEPT II' package. This package is based on the method of moment combined with a transmission-line model. A 1 km long, 132 kV, three-phase, double-circuit transmission line, and a 2km long, 40cm diameter, 1 m high above-ground pipeline are modelled. Extra shielding wires (ESW) under the phase conductors are investigated. Produced voltages in the pipeline are computed under steady-state power frequency (50 Hz) as well as under direct and indirect lightning strikes to the power line. Different current waveforms are simulated to cover the whole range of those of the anticipated lightning. Under lightning strikes, the voltages across line insulators are computed, too. The results reveal that the ESW give many advantages; namely, (1) reducing the power-frequency electric and magnetic fields at the ground level to meet the regularity limits, (2) improving the shielding effectiveness during lightning strikes by reducing the insulator voltages, (3) mitigating the induced voltages in any metallic structure near the power lines, e.g., pipelines, and (4) using them as optical ground wires for telecommunication purposes, where the probability of lightning strikes to such ESW is much lower than that for the normally used grounding wire(s) at the tower top.