Abstract：
With the rapid development of China's economy and the substantial construction of energy transmission networks,
high voltage transmission lines and oil and gas pipelines usually form a "Right-of-Way", especially in space restricted areas. AC
transmission lines can induce AC interference in the pipeline. When the AC current flows out from the defects of the pipeline’s
coating, AC corrosion will be caused. The safe distances between AC transmission lines and pipelines should be clearly defined
for keeping them away from each other at the routing stage, and possible interference on the pipeline will be avoided. In this pa
per, safety indicators for AC corrosion were first identified, then numerical simulation was used to establish the buried pipeline’s
AC interference model. The safe distances in typical conditions were calculated. These include soil resistivity, pipeline coating,
voltage level of HVAC transmission line, three-phase imbalance and pipeline diameter. The results indicated that the higher the
voltage of the transmission line, the greater the safety distance required. For high-voltage AC transmission lines with voltage less
than 220 kV and phase current less than 1000 A, when the distance between the pipelines and the high voltage transmission line
was greater than 868 m, the AC corrosion risk of the pipelines could be ignored. The longer the parallel length was, the greater
the safety distance required. When the parallel length was greater than 40 km, the safety distance did not change much. Soil
resistivity and pipeline coating had obvious effects on the safety distance. The lower the resistivity of the soil, the greater the
safety distance required, and therefore greater safety distance was required when the pipeline was in farmland or saline soil. The
better the coating of the pipeline, the greater the safety distance was required, so a greater safety distance was needed for 3PE
coated pipeline. Three-phase imbalance current had little effect on the safe distances, which indicated that the main source of AC
interference for pipelines near safety distance was the position difference between phase lines, rather than the current imbalance.
The pipeline diameter also had little effect on the safety distance. It was due to the longitudinal impedance of the pipeline being
much lower than the leakage impedance, it had little effect on the longitudinal electric field. And on this basis, a safety distances
map and evaluation method were established. Then, this method was applied to the AC interference assessment of a real pipeline,
and the results showed that the interference risk of a pipeline can be estimated well from the safety distance. The results of this
study provide a method and reference for dealing with pipelines and high voltage transmission lines in “Rights-of-Way”.
