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In this paper, a stochastic approach is combined with field theory and circuit methods to study how the geometrical and electrical properties of holidays (defects or pores in the insulating coating) in a metallic pipeline influence the probability of exceeding the current density limit for corrosion. Three-dimensional FEM simulations are conducted to assess the influence of the shape and electrical resistivity of the pore on the computed spread resistance value. The obtained results are then used to evaluate the probability of exceeding a given current density value for different sizes of pore and soil resistivities. Finally, a case of 50 Hz interference along a pipeline-transmission line routing is examined. The probabilistic approach presented in this paper allows the pipeline sections more subjected to the induced AC corrosion risk to be identified to be used as an auxiliary tool for adopting preventive protection countermeasures. Lastly, unlike most papers devoted to assessing electromagnetic interference on pipelines, the present work uses a probabilistic rather than a deterministic approach, representing its main novelty aspect. [ABSTRACT FROM AUTHOR]

The functionality of buried metallic pipelines can be compromised by the electrical lines that share the same right-of-way. Given the considerable size of shared corridors, computer simulation is an important tool for performing risk assessment and mitigation design. In this work, we introduce an open-source computational framework for the analysis of electromagnetic interference on large earth-return structures. The developed framework is based on FLARE—an efficient finite element solver developed by the authors in MATLAB®. FLARE includes solvers for problems involving static electric and magnetic fields, and DC and time-harmonic AC currents. Quasi-magnetostatic transient problems can be studied through time-marching or—for linear problems—with an efficient inverse-Laplace approach. In this work, we succinctly describe the optimization of time-critical operations in FLARE, as well as the implementation of a transient solver with automatic time-stepping. We validate the numerical results obtained with FLARE via a comparison with the commercial software COMSOL Multiphysics®. We then use the validated time-marching analysis results to test the accuracy and efficiency of three numerical inverse-Laplace algorithms. The test problem considered is the assessment of the inductive coupling between a 500 k V transmission line and a metallic pipeline buried in the soil. [ABSTRACT FROM AUTHOR]

A numerical methodology is proposed for the calculation of transient electromagnetic interference induced by overhead high-voltage power lines in metallic structures buried in soil—pipelines for oil or gas transportation. A series of 2D finite element simulations was employed to sample the harmonic response of a given geometry section. The numerical inverse Laplace transform of the results allowed obtaining the time domain evolution of the induced voltages and currents in the buried conductors, for any given condition of the power line. [ABSTRACT FROM AUTHOR]

Highlights • A method combining 2D finite element computations and circuit analysis is presented. • The circuit analysis forces the axial currents to take the soil as return path. • Any number of conductors can be considered without loss of accuracy. • Any earthing and coating of the pipeline can be considered. • The presented method is consistent with established analytical methods. Abstract In this paper, a novel quasi-three dimensional technique for the study of electromagnetic interferences induced by overhead power lines on buried metallic pipelines located in the same corridor is proposed. The aim of the method is to provide an inherently three dimensional solution to the problem, by using a two dimensional finite element approach. According to the proposed methodology, a bidimensional quasi-magnetostatic analysis is performed on a section of the considered corridor. The three dimensional extension is obtained by using a circuital approach to consistently couple the analysed section with the rest of the system. The analysis of the obtained equivalent circuit finally provides the actual values of the longitudinal electric fields acting on the studied section, and thus allows the solution of the problem. The results obtained from the described procedure have been compared for a few simple interference cases with those obtained using Carson's analytical formulas for the calculation of mutual impedances. Finally, a study on the effects of a non-homogeneous soil structure has been carried out. [ABSTRACT FROM AUTHOR]

In this paper, a strategy for reducing the electromagnetic interferences induced by power lines on metallic pipelines is proposed and numerically investigated. The study considers a set of steel conductors interposed between the power line and the pipeline. Different shapes of conductor cross sections and different magnetic permeabilities are considered, to identify the solution exhibiting the greatest mitigation efficiency for the same amount of material. The investigation is carried out by means of a quasi-3D finite element analysis. Results show that the main mechanism responsible for the mitigation is constituted by the currents induced in the screening conductors by the power line. Hence, a high magnetic permeability can have a detrimental effect since it reduces the skin depth to values below the size of the screening conductor. In this case, a reduction of the screening current and in the mitigation efficiency is observed. Nevertheless, the study shows that the use of strip-shaped screening conductors allows the employment of cheaper magnetic materials without compromising the mitigation efficacy of the screening conductors. [ABSTRACT FROM AUTHOR]