Objective With the vigorous development of cross-regional energy allocation in China, the construction of power transmission lines and oil & gas pipelines has entered a new stage of rapid growth. Consequently, more “shared corridors” for these two transmission systems have emerged, leading to increasingly prominent AC interference between the pipelines and power lines. Particularly during lightning strikes on transmission lines, the high lightning current injects into the soil, causing significant lightning overvoltage on buried pipelines located near the grounding devices of the affected towers. Such overvoltage may ablate or break down pipeline insulation coatings, resulting in fires, explosions, and other accidents, thereby threatening production safety.
Methods This paper aims to develop a solution for effectively assessing the safety of pipelines located adjacent to transmission lines. Lightning current surges were applied to soil samples with varying resistance values to determine soil resistivity under different voltage surges. The subsequent analysis examined variations in soil resistance values due to ionization. The results obtained were used to construct an electromagnetic interference model that incorporates a soil ionization area.
Results By integrating calculations regarding the interference voltage on pipeline coatings, conducted using electromagnetic interference analysis software, the comparison revealed that the interference voltage imposed on the coatings after soil ionization was significantly greater than the results without considering the impacts of soil ionization. The soil ionization caused by lightning strikes emerged as a crucial factor influencing the magnitude of the interference voltage on pipeline coatings, which must not be overlooked in interference analysis.
Conclusion The developed electromagnetic interference model, which incorporates the effects of soil ionization, supports the calculation of safe distances between the pipelines and power lines for various initial soil resistance values, using a withstand voltage limit of 109 kV for 3-layer PE coatings as the safety threshold. Additionally, the assessment of the safety of operators contacting the pipelines, along with the risk of metal ablation damage to the pipe wall, further verified the reliability of the safe distances calculated using this model.
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