High Voltage Direct Current systems are developing fast in China. But the electrodes working in monopolar modes may introduce DC interferences on buried metallic pipelines nearby, and increase the risk of corrosion and hydrogen embrittlement. Focusing on a real case of HVDC interference, this paper aimed to study the field test, the numerical simulation calculation, and the design of mitigation. Firstly, field tests found that a natural gas pipeline system was interfered by a HVDC electrode in Guangdong province. The pipe-to-soil potentials along the pipe had deviations up to 300V, posing severe threats to safety operation of the pipeline system. Then, the numerical simulation technique was used to model the electrode and pipeline system based on field parameters. The interference level was computed and the results showed good agreements with the measured values, which indicated the validity of the model. Finally, for the purpose of interference elimination, the effectiveness of various mitigation methods was computed and discussed, including insulating joints, sacrificed anodes drainage system, zinc ribbon drainage system, impressed current drainage system, etc. Based on the results above, the integrated mitigation of this interference case was designed.
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