yesThis work presents the development of a new approach of modelling the source excitation and the penetration of structures by continuous propagating electromagnetic (EM) plane waves. The technique incorporates the solution of time-dependent Maxwell¿s equations and the initial value problem as the structures are illuminated by the plane waves. The propagation of waves from source excitation is simulated by solving a finite-difference Maxwell's equation in the time domain. Subgridding method is used to condense the lattice at the point of interest locally for observing field distribution in high resolution. The computational burden due to huge number of time steps has been eased by employing quasi-static approach. An example of induced EM fields near an underground pipeline runs parallel to a 132 kV overhead power transmission line (OHTL) has been presented which paves the way in the development of new approach of EM fields interaction modelling.MSCR

Abd-Alhameed, Raed A.

Excell, Peter S.

Hraga, Hmeda I.

Liang, D.T.W.

Ramli, Khairun N.

YesThis work presents the development of a new approach of modelling the source excitation and the penetration of structures by continuous propagating electromagnetic (EM) plane waves. The technique incorporates the solution of time-dependent Maxwell's equations and the initial value problem as the structures are illuminated by the plane waves. The propagation of waves from source excitation is simulated by solving a finite-difference Maxwell's equation in the time domain. Subgridding method is used to condense the lattice at the point of interest locally for observing field distribution in high resolution. The computational burden due to huge number of time steps has been eased by employing quasi-static approach. An example of induced EM fields near an underground pipeline runs parallel to a 132 kV overhead power transmission line (OHTL) has been presented which paves the way in the development of new approach of EM fields interaction modelling.MSCR

Abd-Alhameed, Raed

Bradford Scholars

 The University of Bradford Institutional Repository http://bradscholars.brad.ac.uk This work is made available online in accordance with publisher policies. Please refer to the repository record for this item and our Policy Document available from the repository home page for further information. To see the final version of this work please visit the publisher’s website. Where available access to the published online version may require a subscription. Author(s): Ramli, K. N., Abd-Alhameed, R. A., Hraga, H. I., Liang, D. T. W. and Excell, P. S. Title: Electromagnetic Field Interaction Between Overhead High Voltage Power Transmission Line and Buried Utility Pipeline. Publication year: 2011 Conference title: Progress In Electromagnetics Research Symposium Proceedings, Marrakesh, Morocco, March 20-23, 2011. Publisher:  The Electromagnetics Academy. Link to original published version:  http://www.piers.org/piersproceedings/piers2011MarrakeshProc.php Citation: Ramli, K. N., Abd-Alhameed, R. A., Hraga, H. I., Liang, D. T. W. and Excell, P. S. (2011). Electromagnetic Field Interaction Between Overhead High Voltage Power Transmission Line and Buried Utility Pipeline. In: Progress In Electromagnetics Research Symposium Proceedings, Marrakesh, Morocco, March 20-23, 2011. Cambridge, MA: The Electromagnetics Academy. pp. 1478-1482. Copyright statement: © 2011, The Electromagnetics Academy. Reproduced in accordance with the publisher's self-archiving policy. 1Electromagnetic Field Interaction between Overhead HighVoltage Power Transmission Line and Buried Utility PipelineK. N. Ramli1, 2, Raed A. Abd-Alhameed1, H. I. Hraga1, D. T. W. Liang1, and P. S. Excell31Mobile and Satellite Communications Research Centre, University of Bradford, Bradford BD7 1DP, UK2Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia (UTHM)Parit Raja 86400, Batu Pahat, Johor, Malaysia3Centre for Applied Internet Research, Glyndwr University, Wrexham LL11 2AW, Wales, UKAbstract— This work presents the development of a new approach of modelling the sourceexcitation and the penetration of structures by continuous propagating electromagnetic (EM)plane waves. The technique incorporates the solution of time-dependent Maxwell’s equations andthe initial value problem as the structures are illuminated by the plane waves. The propagationof waves from source excitation is simulated by solving a finite-difference Maxwell’s equation inthe time domain. Subgridding method is used to condense the lattice at the point of interestlocally for observing field distribution in high resolution. The computational burden due to hugenumber of time steps has been eased by employing quasi-static approach. An example of inducedEM fields near an underground pipeline runs parallel to a 132 kV overhead power transmissionline (OHTL) has been presented which paves the way in the development of new approach of EMfields interaction modelling.1. INTRODUCTIONFinite-difference based on integral formulation [1, 2] has been used in the published literature toimprove the accuracy of the finite-difference formulation near the surfaces that does not fit in thelattice or small objects such as thin wires which alter the electromagnetic field distribution signifi-cantly. In this case, analytical expressions have been established to express the field near a particularobject for precise evaluation of the integrals. Many researchers in the past have been promptedto investigate the subgridding technique as an approach to circumventing the problem [3, 4]. Thefirst advantage of using this method is simple to implement for complicated dielectric or metalstructures due to arbitrary electrical parameters can be assigned to each cell on the grid. Second,the entire computational spaces need not to be discretised with a fine grid as it puts unreasonableburden on the computer processing time. The ultimate objective of research in this area is to accessthe appropriateness of the method in determining the amount of EM penetrating fields betweenOHTL and underground utility pipeline. The aim of the present work is to develop the generalcode for solving the electric and magnetic fields within arbitrary metal or dielectric structures,while maintaining a boundary of uncertainty low reflection level in two-dimensional approach.FDTD technique has been well known over the years of its strength with robust simulationtechnique for transient electromagnetic interactions. In this research work, two-dimensional FDTDtechnique is used with subgridding to model the utility pipeline and the overhead high voltagepower transmission line. FDTD technique has been applied to the high voltage power transmissionline analysis in the published literature. Dedkova and Kriz [5] proposed a new effective approachto evaluate the distribution of voltage and current along the nonlinear transmission line by usingFDTD method. An improved technique was proposed by Tang et al. [6] to calculate the transientinductive interference in underground metallic pipelines due to a fault in nearby power lines. Thefrequency-dependent problem in the analysis of transient interference was solved in phase domainbased on FDTD method. Lu and Cui [7] used FDTD method to calculate the wave processes ofvoltage and current distributed along the three-phase 500 kV busbars and the power lines withoutload in the substation of multi-conductor transmission lines (MTL). The iterative formulas werepresented to determine the boundary conditions at the node of the branches. The work was extendedto transmission line network and non-uniform line [8].2. METHODFigure 1 depicts the cross section and the dimension of a common corridor in which a buried utilitypipeline runs parallel to a 132 kV overhead power transmission line. The height from the ground to2Figure 1: Outline of standard circuit 132 kV steel lattice transmission high voltage suspension towers (notto scale).the bottom conductors was 15m. The overhead ground wire was located at the top of the tower. Inthis case, the height to the earth surface is 27m. The phase conductors for the bottom, middle andtop were collocated horizontally with a separation of 4.0m, 4.5 m and 4.0m respectively betweentwo adjacent conductors. The three phase steel lattice transmission high voltage suspension towerwas designed with 6 cables. These cables were used as the source signal which propagates inside theproblem space. Each of the 2 cables carries the same phase of the AC current. The simulation wascarried out using the quasi-static FDTD at the transformed intermediate frequency of 460 kHz andthe overall model was then transformed back to the proposed lower frequency of 50Hz. Quasi-staticapproximation was obtained by using the expression [9–11]:~E (f) =( ωω′)[σ′ (f ′) + jω′ε (f ′)σ (f) + jωε (f)]~E′(f ′)(1)where ~E (f) is the resultant internal electric field (V/m), ~E′ (f ′) is the scaling internal electricfield (V/m), f is the frequency of interest (Hz), f ′ is the scaling frequency (Hz), ω is the angularfrequency of interest (s−1), ω′ is the scaling angular frequency (s−1), σ is the conductivity of theobject (S/m), and σ′ is the scaling conductivity of the object (S/m). By assuming ωε (f)¿ σ (f)and ω′ε′ (f ′ ¿ σ′ (f ′), then Equation (1) can be approximated as follows [9–11]:~E (f) ∼=[fσ′ (f ′)f ′σ (f)]~E′(f ′)(2)Sinusoidal wave excitation of 460 kHz (λ = 652.17m) was applied at each of the power transmissionline cables. The pipeline was separated at a distance of 100m from the steel lattice suspensiontowers and buried 2m beneath the surface of the earth. The soil in the common corridor wasdesigned to be inhomogeneous. The computational region at the coarse grids was discretised ata spatial resolution of 2,609 cells per wavelength (∆y = ∆z = 25 cm). Subgridding involves localmesh refinement in the pipeline and some part of the ground in order to determine the propagationof the waves inside that area while observing the change in the fields. The computational space forthe main region was 521 cells ×145 cells (130.25m×36.25m). The computational space for subgridarea was 10 cells ×10 cells. The ratio of the coarse to the fine grids was 4 : 1.3. SIMULATION RESULTSSubgrid technique was validated by illustrating example in Fig. 2. The problem space was excitedby sinusoidal wave source at 1800MHz. The fields at the same point without subgrid (Fig. 2(a))and with subgrid (Fig. 2(b)) were observed and compared. In addition, they were found to beidentical to each other as depicted in Fig. 3.3(a) (b)Figure 2: Problem space: (a) without subgrid, (b) with subgrid.(a) (b)Figure 3: The electric field at one point without subgrid (Ez) and with subgrid (Ezg): (a) when sinusoidalwave was excited, (b) when gaussian pulse was excited.Figure 4: The electric field Ez distribution in the main FDTD grid.The computation efforts can be reduced using quasi-static method due to the largest compu-tational size was less than 0.2λ. The simulation was carried out by assuming normal conditionof OHTL. Fig. 4 illustrates the electric field distribution in the main FDTD grid. The EM wavepropagates from the 6 cables of the suspension tower to the surrounding area of air, ground and thepipeline. It varies from 1.0V/km (0 dBV/km) to 1.78× 109V/km (185 dBV/km). The fields insidethe metallic pipeline were found to be zero as depicted in Fig. 5(a) due to the excess electrons atthe surface of the metal preventing any incoming propagating waves from penetrating the pipeline.The electric field distribution surrounding the pipeline alters from 3.16V/km (10 dBV/km) to1.0× 103V/km (60 dBV/km). Some of the waves were reflected back to the surface of the groundthus producing induced EM fields as shown in Fig. 5(b). The results were verified by comparingthem with [12] which shows good agreements. Phase imbalance in the line may be produced dueto the difference in the relative distance of each phase from the nearby pipeline. Under fault con-dition, the currents on the faulty phases of transmission lines were high. This in turn will induceAC voltage on the pipeline and create shock hazard rather than corrosion.4(a) (b)Figure 5: (a) The electric field Ezg distribution in the subgrid section. (b) The induced electric field Ez at1.75m above pipeline.4. CONCLUSIONSAn approach to model the interaction between overhead transmission lines and buried utilitypipeline at power-line frequency has been presented. This uses the FDTD technique for the wholestructure of the problem combined with subgridding method at the object of interest. The com-putational burden due to huge number of time steps in the order of tens of millions has beeneased to tens of thousands by employing the method called quasi-static approach. The use of inho-mogeneous soil in the common corridor permits a non-trivial proximity region of authentic groundproperties to be simulated. Profound investigation of the interaction between electromagnetic fieldsand natural or utility arrangement with different electrical characteristics at different level of spatialresolution can be assisted by such tools. The combination of frequency scaling FDTD subgriddingapproach with arbitrary inhomogeneous soil element model paves the way in the development ofnew approach of EM fields interaction modelling.ACKNOWLEDGMENTThe financial support from Ministry of Higher Education Malaysia and Universiti Tun Hussein OnnMalaysia (UTHM) is gratefully acknowledged.REFERENCES1. Taflove, A. and S. C. Hagness, Computational Electrodynamics: The Finite-Difference Time-Domain Method, 3rd Edition, Artech House, Boston, 2005.2. Shreim, A. M. and M. F. Hadi, “Integral PML absorbing boundary conditions for the high-order M24 FDTD algorithm,” Progress In Electromagnetics Research, Vol. 76, 141–152, 2007.3. Ramli, K. N. and R. A. Abd-Alhameed, “Modelling of complex electromagnetic problemsusing FDTD subgridding methods,” 9th Informatics Workshop for Research Students, 200–201, University of Bradford, UK, 2008.4. Wang, S. M., F. L. Teixeira, R. Lee, and J. F. Lee, “Optimization of subgridding schemes forFDTD,” IEEE Microwave and Wireless Components Letters, Vol. 12, 223–225, 2002.5. Dedkova, J. and T. Kritz, “FDTD analysis of a nonlinear transmission line,” Proceedings ofProgress In Electromagnetics Research Symposium, 282–285, Beijing, China, 2009.6. Tang, J., X. Cui, L. Qi, T. Lu, L. Li, P. Zhu, G. Yang, and W. Zhang, “Analysis of transientinductive interference in underground pipelines due to faults on nearby power lines,” COM-PEL: The International Journal for Computation and Mathematics in Electrical and ElectronicEngineering, Vol. 26, 1346–1363, 2007.7. Lu, T. and X. Cui, “Transient analysis of wave processes for multi-conductor transmission lineswith branches using FDTD,” IEEE International Symposium on Electromagnetic Compatibil-ity, Vol. 2, 699–703, 2000.8. Lu, T., L. Qi, J. Li, and X. Cui, “Application of multi-conductor transmission lines on thetransient analysis in power substation,” Asia-Pacific Conference on Environmental Electro-magnetics, 198–201, 2003.59. Guy, A. W., S. Davidow, G. Y. Yang, and C. K. Chou, “Determination of electric currentdistributions in animals and humans exposed to a uniform 60-Hz high-intensity electric field,”Bioelectromagnetics, Vol. 3, 47–71, 1982.10. Golestani-Rad, L., B. Elahi, and J. Rashed-Mohassel, “Investigating the effects of externalfields polarization on the coupling of pure magnetic waves in the human body in very lowfrequencies,” BioMagnetic Research and Technology, Vol. 5, 1–5, 2007.11. Gandhi, O. P. and J. Chen, “Numerical dosimetry at power-line frequencies using anatomicallybased model,” Bioelectromagnetics, Vol. 13, 43–60, 1992.12. Amer, G. M., “Novel technique to calculate the effect of electromagnetic field of H.V.T.L. onthe metallic pipelines by using EMTP program,” 18th International Conference and Exhibitionon Electricity Distribution (CIRED), 1–5, Turin, Italy, 2005.

Electromagnetic Field Interaction Between Overhead High Voltage Power Transmission Line and Buried Utility Pipeline.

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