Study On Coupling Interference Of High Voltage Transmission Line To Buried Pipeline

With the continuous development of the national economy,the construction of the national strategic energy channel is also developing rapidly,and the demand for power,fuel oil,natural gas and other energy is increasing day by day.Due to the uneven distribution of resources,rugged and complex terrain,and the shortage of construction land in China,the power facilities and pipeline facilities are very similar in the principle of construction site selection,which inevitably leads to the "public corridor" shared by high-voltage transmission lines and buried metal pipelines,so the electromagnetic interference of high-voltage transmission lines to pipelines is inevitable.When the transmission line is in fault operation,the over-voltage generated on the pipeline may break through the pipeline coating,which will lead to oil and gas pipeline explosion and other accidents.Therefore,it is very important for the safe operation of oil and gas pipelines to study the AC electromagnetic interference of transmission lines and buried oil and gas pipelines.In this paper,the coupling over-voltage distribution of oil and gas pipelines and the protection measures of pipeline over-voltage are studied.Firstly,the influence mechanism and calculation method of AC transmission line on oil and gas pipeline are analyzed.Secondly,the electromagnetic interference model of 500 k V transmission line parallel to oil and gas pipeline and the simplified model of lightning transmission line are established by CDEGS software.The short circuit and lightning fault of transmission line are simulated and analyzed respectively,and different pipeline spacing,soil characteristics are studied the influence of short-circuit current amplitude,lightning current amplitude and other factors on the over-voltage of the pipeline.Through the CDEGS and COMSOL software to establish three-dimensional grounding grid and pipeline model to study the interference degree of grounding grid materials and types to pipeline overvoltage;finally,for the oil and gas pipeline overvoltage safety protection measures research: comparative analysis of the relief effect of bare copper tape and graphite composite shielding wire to pipeline overvoltage under fault operation conditions.Based on the simulation,the influence of the grounding drainage method on the lightning over-voltage of the adjacent pipeline is calculated,and the construction suggestions of the over-voltage protection of the oil and gas pipeline under the lightning stroke condition are given.The results show that the distance between the transmission line and the oil and gas pipeline,the amplitude of short circuit current and the soil resistivity have great influence on the over-voltage of the pipeline.When lightning strikes transmission lines,the amplitude of lightning current,soil structure and the distance between lines and pipelines have great influence on the over-voltage of pipelines.The shape of the grounding device affects the direction and effect of lightning current dispersion,and the shape of the grounding device has great interference on the over-voltage of the pipeline.The influence of grounding device materials on the over-voltage of pipeline is limited,so the non-metallic grounding grid can be selected under the premise of considering the safe operation of transmission line and pipeline.The transformation of grounding grid characteristics can be used as a new research direction of buried oil and gas pipeline protection.After laying the shield wire,it has certain effect on reducing the electromagnetic interference of the pipeline.The ? 28 mm graphite composite shield wire has similar protective performance with the bare copper strip.For the sake of technology and economy,the method of replacing bare copper wire with graphite composite is put forward.The new protection measures of over-voltage based on the grounding drainage method can change the direction of the fault current and the distribution of the ground electric field,so as to reduce the harm of the fault current to the over-voltage of the pipeline.The conclusion of this paper can provide reference for the design,construction and safety protection of oil and gas pipeline.