Voltage induction on pipelines caused by AC currents in adjacent power lines is always a concern for pipeline and power line companies. In recent years, the AC currents have become increasingly distorted due to the proliferation of power electronics based devices. Based on the Fourier theory, the AC currents can also be said to contain harmonic currents. Since the severity of voltage induction is proportional to the frequency of the AC current, one can expect that the harmonic currents may cause additional voltage inductions on pipelines.
This project studies this concern. The project has established a measurement method that can determine the relative severity of voltage induction due to the fundamental frequency component and the harmonic components in the AC current. This method determines the induction levels without considering the configurations and the currents in the power lines adjacent to the pipeline. As a result, it can be easily adopted to conduct voltage induction surveys by pipeline as well as power line companies. The project applied the method to assess the voltage induction levels for 20 plus transmission and distribution lines. The results show that some sub-transmission lines and residential distribution feeders can produce significant harmonic voltage induction. The most pronounced harmonic induction occurs at the 3rd harmonic frequency. The voltages induced by the harmonic currents can be higher than those induced by the fundamental frequency current.
Inductive coordination, Voltage induction, Harmonic current, Pipeline, Overhead power line, AC induction measurement, Probe-wire.