直流接地极电流干扰下埋地金属管道防护距离影响因素研究

Study on Influencing Factors on Buried Metal Pipeline Protective Distance Under DC Grounding Electrode Interference

随着直流输电工程建设的快速发展及直流输电工程与埋地金属管道相邻不断增多,接地极极址的选择变得越来越困难。接地极对管道直流腐蚀影响的程度不仅与接地极电流和接近距离有关,还与土壤电阻率、土壤pH值和管道防腐层类型有关。文中在管道电路模型的基础上,建立了考虑管道极化效应的电路模型。通过文中计算方法的计算结果与CDEGS计算结果的对比,验证了文中算法的正确性。获得了典型设计参数下接地极与埋地金属管道的可供工程参考的防护距离,分析了土壤电阻率、土壤pH值、管道防腐层类型对接地极电流干扰下管道防护距离的影响。土壤电阻率和管道防腐层类型对管道防护距离影响较大,土壤pH值几乎不改变管道的防护距离。

With the rapid development of HVDC transmission project construction, more and more DC transmission projects adjacent to buried metal pipeline. The choice of grounding electrode location becomes more and more difficult. The degree of corrosion influence of grounding electrode on pipelines is not only related to grounding electrode current and distance, but also to soil resistivity, soil pH value and type of pipeline coating. On the basis of the pipeline circuit model, this paper establishes a circuit model considering the polarization effect of pipeline. Compared the calculated results with CDEGS, the circuit model and calculation method is proved to be correct. The engineering reference protective distance between grounding electrode and buried metal pipeline under typical design parameters is obtained. The influence of soil resistivity, soil pH value and type of pipeline coating on pipeline protective distance under the interference of grounding electrode current is analyzed. Soil resistivity and type of pipeline coating have great influence on pipeline protective distance, and pH value of soil almost does not change the protective distance of pipelines.