晚期高空电磁脉冲作用下油气管网地磁感应计算模型与峰值响应特征OA

The late-time high-altitude electromagnetic pulse(HEMP)induces geoelectric fields at the earth's surface through disturbances in the geomagnetic fields.The geoelectric fields generate geomagnetically induced currents and pipe-to-soil potentials in pipelines,which pose a potential threat to the safe operation of oil/gas pipeline networks.Hence,assessing the electromagnetic coupling response characteristics of pipeline networks to late-time HEMP is critical for ensuring infrastructure resilience.The coupling mechanisms of late-time HEMP and geomagnetic storms on pipelines are similar;however,significant differences exist in their space current source systems and the associated electromagnetic environment distributions.Toward the quantitative assessment of electromagnetic interference on pipeline networks caused by late-time HEMP environments,this paper establishes an electromagnetic coupling model to evaluate the voltage and current responses in pipeline networks under late-time HEMP.Furthermore,the study analyzes the influence of pipeline length,terminal load impedance,spatial orientation and coating defects on the peak response.Finally,the distribution characteristics of pipeline responses are compared during E3A and E3B phases of late-time HEMP. This study presents a comparative analysis of the spatial distribution and peak response of the geomagnetic induction in pipeline networks in cases of spatially uniform and non-uniform geoelectric fields induced by late-time HEMP.It constitutes an effective tool for identifying the worst-case scenarios and vulnerable areas under late-time HEMP environments.For a uniform geoelectric field distribution,explicit formulas are derived for the peak responses of the voltage and current in the pipeline,along with their corresponding spatial coordinates.For a non-uniform geoelectric field distribution,the statistical distribution of the pipeline's peak response is provided using a spatial sampling method.With respect to the peak response of a single pipeline under a uniform electric field,the maximum peak voltage occurs when one terminal is ideally grounded and the other is ideally insulated,whereas the maximum peak current occurs when both terminals are ideally grounded.When the pipeline is grounded asymmetrically at both terminals,the peak voltage appears at the terminal with higher grounding resistance,whereas the peak current arises in the pipeline section in proximity to the terminal with lower grounding resistance.Both peak voltage and current rise progressively with pipeline length before approaching saturation,and the length at which 95%of the saturated response is attained can reach several hundred kilometers.The peak voltage exhibits a shorter saturation length of the pipeline than current,corresponding to a faster saturation process.The saturation level of voltage depends on the propagation constant of the pipeline,whereas that of current depends on the series impedance per unit length.Moreover,the analysis reveals a significant enhancing effect of the lateral earth conductivity heterogeneity on the pipeline responses.Results for the coastal case study presented indicate that the PSP amplitude increases by over 20%compared with the 1D layered earth model.Substantial spatial variations in voltage response are observed throughout the pipeline network under non-uniform E3B geoelectric fields with different ground zero locations.For both the E3A and E3B phases,east-west oriented pipelines exhibit relatively higher peak responses,whereas north-south oriented pipelines show relatively lower peak responses.Case results indicate that during the E3B phase,the peak response of east-west oriented pipelines exceeds that of north-south oriented pipelines by over 70%. Future work will further investigate the influence of variations in field source parameters and realistic earth resistivity structures on the electromagnetic coupling response of pipeline networks to late-time HEMP.