Evaluation of the Interference Effects of HVDC Grounding Current on a Buried Pipeline

The stray current created by the grounding current of HVdc ground electrode will accelerate the corrosion of the oil and gas pipeline when the HVdc is operate in single-pole mode. The magnitude of the stray current and the pipe-soil potentials (PSP) offset are indexes to evaluate the corrosion situation of the pipeline. An algorithm of the stray current and PSP of an oil pipeline generated by the Gaoqing ground electrode of Zhalute-Qingzhou ±800-kV ultrahigh voltage direct current project is put forward, the influence of potentiostat output, defects of insulation coating, and the insulation joint are considered for the first time. The stray current and PSP of the pipeline is calculated. The correctness of the algorithm is verified by the comparison of the calculation results and the monitoring data. The results show that the magnitude of the stray current and the PSP offset of the pipeline near an oil transmission station is the largest, the PSP offset is beyond the limit value prescribed by the national standard, and the potentiostat cannot provide an effective protection for the pipeline when the HVdc is operated in single-pole mode with the transmission load reaches to 2500 MW.