An alternating current (AC) interference study was conducted in 2019 following a utility development project that included constructing a new substation and upgrading approximately 24 km of new AC transmission powerline sections in Alberta, Canada. The study comprised six transmission powerlines owned by one utility and eight pipelines owned by two different operators.

The modelling results showed touch voltage hazards under steady-state and fault conditions and susceptibility to AC corrosion and coating stress above the established limits in the unmitigated state.

A shared AC mitigation system was designed to eliminate the hazards caused by AC interference on all eight pipelines. This approach reduced overall mitigation requirements, number of site visits, construction footprint, environmental impact, and project costs.

This paper describes the mitigation system's design, installation, and commissioning and discusses the benefits of a shared AC mitigation system approach.


AC interference analysis between high voltage AC (HVAC) powerlines and buried pipelines is a matter of current interest due to the growing number of right-of-ways shared between powerline and pipeline infrastructure. This is only expected to increase as the worldwide energy demand grows considerably over the next 30 years,1 and stricter environmental regulations and policies are applied. Therefore, AC interference will continue to be an issue of concern for powerline and pipeline operators to protect the public, environment, and maintain asset integrity.

AC interference hazards on pipelines resulting from nearby powerlines can occur under steady-state (normal operation) and fault conditions. Under steady-state conditions, the pipeline is subject to AC voltages induced by electromagnetic coupling between the pipeline and nearby HVAC powerline. These induced voltages can result in electrical shock to any person who touches an appurtenance that is electrically continuous with the pipeline. Induced voltages can also result in accelerated corrosion at pipeline coating defects, i.e., AC corrosion, as the AC current is discharged through any coating defects.

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