Active Mitigation of Induced Voltage on Buried Pipelines

Abstract

Buried pipelines that share a common corridor with nearby overhead AC power lines experience voltage induction. The induced voltages can cause personnel safety and pipeline corrosion problems. Industry has a requirement to reduce the induced voltages below an acceptable level. In view of the limitations of existing methods to reduce the induced voltages and contributions of power line harmonic currents to the voltage induction, this thesis proposes an active method that can neutralize the induced 60Hz and harmonic voltages in buried pipelines. The idea of the proposed mitigation method is to apply proper neutralizing voltage to the two terminals of the buried pipeline which is parallel to overhead AC power lines. A feedback control system is embedded in the active mitigation device to automatically adjust the generation of the neutralizing voltage. This thesis shows that, by applying two proper neutralizing voltage sources at the two terminals, the whole induced voltage along the parallel zone of the buried pipeline can be mitigated. Methods to estimate the voltage and power ratings of active sources are proposed. Solutions for dealing with some practical issues are also recommended. Simulation studies are conducted in this thesis to verify the proposed method and to determine the main factors affecting the active mitigation device and its design parameters. The method of the probe-wire-based field measurement is also investigated to help the design of the mitigation device.