Uncertainty Quantification Of Response Of Buried Pipeline To Electromagnetic Pulse

As the electromagnetic environment is more and more complex,the electromagnetic factors of affecting the oil and gas pipelines increase.High-altitude electromagnetic pulse(HEMP)is one of the most important electromagnetic factors.It can induce voltage and current on pipelines.If the voltage is too high,it may break down the coating of the pipelines,and even endanger the personal safety of operators and maintenance personnel.At the same time,the induced current may accelerate the corrosion of the pipelines;moreover,the input parameters may deviate from the preset value due to some uncertainty factors when calculating the coupling response of conductors,it can be seen that the deterministic results are not comprehensive when the inputs are determined;therefore,it is of great significance to study the uncertainty quantification of the coupling response of buried pipeline to high-altitude electromagnetic pulse(HEMP).Firstly,based on the transmission line theory,the calculation model of pipeline earth transmission line is established,and the differential equation of current and voltage for electromagnetic coupling of buried pipeline is solved according to the idea of synthetic wave,then the BLT equation for calculating current and voltage is obtained.The HEMP environment of buried pipeline is analyzed,and the influence of incident state of electromagnetic wave and buried depth on the underground excitation electric field is studied.The propagation law of the exciting electric field under the ground is obtained.When considering the uncertainty of input parameters,the efficiency of traditional Monte Carlo method(MC)decreases dramatically with the increase of the number of samples used.Based on the stochastic collocation method(SC)and stochastic reduced order models method(SROM),the coupled response calculation model of buried pipeline with uncertain parameters is constructed,the selection method of collocation points of stochastic collocation method and sample points of stochastic reduced order models method is studied.When calculating the coupled response of buried pipeline to HEMP,the absolute value of peak value of time domain response is studied.When only one input parameters of geoelectric conductivity,buried depth and load are random variable,taking the MC method as a reference,the SC and SROM method are compared with the MC method respectively,and obtain the application of two methods to a single random variable,then the effectiveness of the two methods is verified.In addition,due to the complexity of buried pipeline environment,this paper also studies the coupled response of buried pipeline with two and three uncertain parameters,and mainly divide the input parameters into two groups:one group includes elevation,azimuth and field source azimuth,the other group includes earth conductivity,buried depth and load at both ends of pipeline,when two and three parameters of the two group parameters are uncertain input variables respectively,the statistical information of coupled response of buried pipeline is obtained,and the relative errors of SC and SROM method with different sample numbers are obtained,and the applicability of the two methods to multiple random variables is evaluated.Then,the relevant statistical information with four uncertain variables(elevation,azimuth,field source azimuth,pipeline corner)is obtained by SC method.Finally,the variance analysis method of uncertain input parameter sensitivity is introduced.Based on the stochastic collocation method(SC),the sensitivity of HEMP coupling response of buried pipeline to uncertain input parameters is studied.The sensitivity index of parameters is obtained,and the importance of parameters is ranked according to the sensitivity index.The research methods and results have certain reference value for the uncertainty quantification analysis of electromagnetic compatibility of buried pipeline.