Research On Interference Of HVDC Grounding Electrode To Pipelines In Mountainous Areas

In recent years,the oil and gas pipeline transportation and power transmission industries have developed rapidly.In the southwest,the oil and power transmission system is very dense.In addition,its complex mountainous terrain and soil environment have brought problems that cannot be ignored to pipeline stray current interference.First of all,the mountainous terrain has large ups and downs,which brings differences in the continuity of stray current flow and the uniformity of distribution in the earth.Secondly,the distribution of soil and rock in mountainous areas is complex,and the soil resistivity changes greatly,which will also affect the flow of stray current.Therefore,studying the interference of the high-voltage DC grounding electrode on the pipeline under the complex mountainous terrain and obtaining the stray current flow direction and distribution in the complex mountainous environment is of great significance to the safe operation of the pipeline.This paper uses boundary element software to establish the HVDC interference model of the hillside pipeline.The interference degree of different grounding electrode discharge parameters on the pipeline is calculated,and the influence of grounding electrode position,output current,and discharge polarity on high-voltage DC interference is obtained.The results show that when the distance between the grounding electrode and the pipeline is greater than the range of the mountain slope,and the influence of hillside undulation on pipeline interference can be ignored.The interference of the cathode discharge on the pipeline near the grounding electrode is greater than that of the anode discharge on the pipeline.Secondly,the HVDC interference model under different hillside terrain was established,and the pipeline and ground potential distribution under different terrain conditions were calculated,and the influence law of hillside slope,hillside soil resistivity,number of hillsides,and pipeline laying position on HVDC interference was obtained.The pipeline potential at the most severely disturbed position of the hillside pipeline under different parameters is calculated,and the high-voltage direct current interference potential calculation model under the threedimensional terrain is obtained.The results show that the 15-degree hillside has the greatest impact on pipeline HVDC interference;Under uniform soil terrain,pipeline interference is more serious under higher soil resistivity.Under layered soil terrain,when the hillside soil resistivity is small,the potential of the hillside pipeline will be more severely disturbed;The high-voltage direct current interference potential calculation model under the three-dimensional terrain can more accurately reflect the pipeline potential at the most severe site interference position,and it is concluded that the safety distance between the ground electrode and the pipeline is 55 km.Based on the interference analysis of HVDC to mountain pipelines,a high-voltage direct current interference model of an actual mountain pipeline was established,the accuracy of the model was analyzed,and the interference degree of the entire pipeline was calculated.The results show that when the earth electrode is discharged,the depth of the soil calculation domain shall not be less than 500 km,and the calculation domain shall not be less than 6 times of the pipeline in the X and Y directions。Under cathodic protection,the error of monitoring data and simulation data of 31 smart piles on site is within 20%,and the error of 24 points is within 10%.Under the interference of different ground electrodes,the model error is within 15%.The research results can provide references for pipeline and power professionals to design circuit routing and take safety protection measures.