Montoring and Mitigation Design for Crude Oil Pipeline Interfered by Mixed AC Stray Current

A crude oil pipeline is adjacent and parallel to a high-voltage AC transmission line and a electrified railway at the same time. In order to study the degree and rules of AC interference to pipeline, the AC voltages and AC current densities along the pipeline were monitored for 24 hours through a data logger. And numerical simulation technology was used to calculate interference protection measures for severely interfered pipeline sections. The results show that the pipeline was interfered by a mixture of the electrified railway and the high-voltage AC transmission line. The AC voltage reached 44.48 V and the AC current density reached 1 248.66 A/m², exceeding the limits specified in the standard. When the pipeline was interfered mainly by the transmission line or the electrified railway, the peak values of the AC voltage mainly appeared where the relationship between the interference source route and the pipeline route changed. In the case of mixed interference, the interference of electrified railway and transmission line was superposed, and the interference of AC voltage and amplitude of interference were disordered. Installing a total of 1 220 m of zinc-belts at 9 AC discharge points along the pipeline could reduce the AC interference level of the pipeline to below the limits specified by the standard.