Study On Disturbance Law Of HVDC Transmission Line To A Buried Metal Pipeline

China has witnessed a rapid development of the national economy.These years HV, UHV DC transmission project as well as petroleum and natural gas pipeline project catches a pace of this high speed trend.China has announced the completion of several DC transmission projects before2020.And with the construction of the first, second and third pipeline of west to east gas project,we will build up a net work of petroleum and natural gas pipelines in every province at the end of the "Twelfth Five Year Plan". however, because of the similar location principles or practical constraints of this two project, inevitably, DC transmission line shares the same public corridor with petroleum and natural gas pipeline.Additionally they may cross or parallel in some areas.To assure underground pipelines’safe operation near DC transmission lines becomes an important subject for pipeline operation and management department to study on. Therefore, research on the disturbance laws HVDC transmission lines on underground oil and gas pipeline and protection technology is very necessary.In view of the HVDC (High Voltage Direct Current referred to as HVDC) transmission line and underground pipeline’s characteristics, the geometric model of underground pipeline under the influence of HVDC was built. Numerical simulation of the geometric model was achieved by using ANSYS-CFX software; so that quantitative research could be done, which studied the disturbance laws of HVDC transmission line have on the underground pipeline in the vicinity of, considering five factors as the coating surface resistance, soil resistivity, the distance between substation and interfered pipeline, the DC current in substation, the longitudinal resistance of interfered pipeline. In accordance with the analysis of HVDC interference on pipeline, indoor experiment device able to simulate the disturbance from HVDC was set up. A stable simulation model has been chosen from numerous experimental models, based on which corrosion on pipeline caused by HVDC in different media could be studied.The study of the influence of various factors on the interference law has shown that the interference intensity increases with pipe coating level of resistance in the form of index; the interference intensity increases with grounding into current and soil resistivity linearly; interference intensity decreases with the distance of HVDC converter station grounding and pipeline in the form of exponential; interference intensity decreases with the pipeline longitudinal resistance in the form of a quadratic function. Corrosion test has shown that interference corrosion is mainly influenced by external DC interference, pipeline corrosion speed and current density of flow point makes a proportional linear relation. Based on the numerical simulation and experiment;and according to the results of this analysis, protection method of target pipeline against HVDC transmission line was put forward,which was forced drainage and drainage by grounding. The conclusion of this thesis is of great significance on oil and natural gas pipeline protection and to extend the service life of the pipeline.