Mitigation of induced voltages and AC corrosion effects on buried gas pipeline near to OHTL under normal and fault conditions

• The inductive and conductive coupling between the buried gas pipeline and the overhead transmission line (OHTL).
• The induced voltages along the length of the buried gas pipeline (measured and calculated values).
• Normal and fault conditions of the OHTL.
• Mitigation system for the induce voltage under normal and fault conditions of the OHTL.

In this paper the induced voltages along the length of the buried gas pipeline, due to the inductive coupling and conductive coupling between this pipeline and the overhead transmission line (OHTL), are calculated under normal and fault conditions of the OHTL. Also, this paper deals with the mitigation of these induced voltages.Fault conditions of the OHTL include symmetric and un-symmetric faults. Where, ATP software is used to simulate the OHTL under all fault conditions. The obtained results from the ATP program are used to calculate the pipeline induced voltages under both normal and fault conditions.Mitigation system to minimize the impact of the OHTL on pipelines at normal and fault conditions is designed. Under normal condition, the pipeline induced voltages, after earthing system (mitigation system) was erected, are measured and compared with the calculated values.Also, pipeline coating discharging current and pipeline AC current density due to inductive coupling under normal operation and due to inductive and conductive coupling under single phase to ground fault condition of the OHTL, before and after erecting the mitigation system, are calculated and analyzed.