Computational model of safe distance between HVAC transmission line and parallel buried pipeline

Objective The vigorous development of China's economy has stimulated the development of public energy corridors. Owing to the similar preference in choosing sites for overhead power lines and oil-gas pipelines, these two kinds of corridors frequently intersect, run in parallel, or closely approach each other, exacerbating AC corrosion issues in the pipelines attributed to electromagnetic induction. These deficiencies may lead to oil and gas leaks, fires, and explosions, culminating in substantial economic losses and casualties.

Methods This study focused on transmission lines featuring typical voltage levels of 35 kV, 110 kV, 220 kV, and 500 kV. CDEGS numerical simulation software was utilized to establish an electromagnetic interference model. A single-variable method was used to calculate AC interference between power lines and oil-gas pipelines across various conditions. The ultimate approach distances (safe distances) between HVAC transmission lines and buried pipelines within the parallel zones were determined based on a judgment index of AC current density set at 30 A/m².

Results Safe distances expanded as the parallel lengths of power lines and oil-gas pipelines extended. Minor fluctuations occurred in these distances once parallel lengths exceeded 20 000 m. With increasing soil resistivity, safe distances between 35 kV transmission lines and respective pipelines gradually reduced, while those in scenarios with 110 kV and higher voltage levels generally decreased following an initial increase. In scenarios of the same voltage level, safe distances were shorter in single-circuit tower power line setups compared to double-circuit tower configurations.

Conclusion Considering the intricate positional relationships between transmission lines and pipelines in actual applications, this study adopted the model equivalent method to "convert curves into tangents". It introduced a calculation approach for determining equivalent spacings between zigzag pipelines and corresponding HVAC transmission lines based on the number of turning points in pipeline routes. The effectiveness of this model was verified through a comparison of the calculation results and simulation data.