Assessment of induced potentials on pipelines from high voltage power lines

Abstract

Pipelines located near to high voltage power transmission are subjected to electromagnetic induction (EMI) causing an induced AC potential on the pipeline due to electromagnetic couplings (EMC). This induced potential can reach dangerous levels, resulting in potentially unsafe operating conditions for utility \ personnel and those accessible to the public at large. Furthermore, such induced potential can exacerbate pipeline corrosion and cause undesirable electromagnetic coupling on neighbouring communication networks. The impact of electromagnetic induction between the high voltage power transmission systems and the pipeline is mainly due to the electromagnetic coupling mechanisms (capacitive, inductive, and conductive) since the pipeline becomes influenced by both electric and magnetic fields; thereby causing an induced potential. This research aims to:  Provide better understanding of touch and step potentials causing hazardous issues due to EM couplings between high voltage transmission and the nearby located pipeline.  Investigate the electromagnetic coupling and induced potentials on the pipeline caused by an extra high voltage AC/DC hybrid system; and compare the influence of these emerging configuration. This thesis assesses the EMI impacts of high voltage power transmission on a nearby located pipeline with respect to three criteria: pipeline sections, soil nature /contents (soil resistivity) and location profiles of the pipeline. The possible locations of the pipeline: under/ above ground and two possible power systems operation situations: steady state and transient fault situations have been comprehensively addressed. Also, observations have been presented for different load currents, fault currents and high voltage levels systems including AC, DC and AC/DC hybrid systems. To achieve expected and consistent results, use of integrated engineering software tools designed to accurately analyse problems involving grounding, earthing, electromagnetic fields, electromagnetic coupling, and transient phenomena of electromagnetic have been applied. These softwares are: the commercially well used current distribution electromagnetic interference grounding and soil structure analysis software (CDEGS) and the alternative transient program / electromagnetic transient program (ATP/EMTP). Use of ATP/EMTP has been very sparsely used for the configuration studied in this thesis, which is an important contribution arising from this research. Findings of this research are expected to provide better understanding of the impact of EMC between high power transmission systems and the pipeline, and also investigate the safest soil nature (soil resistivity) and location profiles for locating necessary pipelines such as, water and gas pipelines since the safety and protection perspective of these pipelines needs to be seriously considered for preventing hazardous and corrosion issues which may be caused by EMC phenomena between high voltage transmission and the nearby pipeline.