The Capacitive Coupling Between EHV Lines and Nearby Pipelines - IEEE

IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 19, NO. 3, JULY 2004 1225

The Capacitive Coupling BetweenEHV Lines and Nearby Pipelines

Mohamed M. Saied, Senior Member, IEEE

Abstract—This paper addresses the effect of the electrostaticfield due to extra high voltage (EHV) overhead transmission lineson pipelines in the vicinity of those power lines. Two measures forthis effect are used: the maximum electric field on the pipe sur-face and the total electric charge on the pipeline per unit length.A mathematical model is presented for assessing these two mea-sures. The results of applying the model to a situation involving asingle-circuit, six-bundle, three-phase, 750-kV EHV line with flatconductor configuration are presented and discussed. The first setof results refers to a parallel pipeline of radius 0.5 m. The depen-dence of both the maximum electric field (at the top of the pipe)and the charge per meter on the distance between the pipeline andthe tower center is similar to the distribution of the electric fieldbeneath the tower at the ground surface. It shows maxima of bothquantities if the pipe is exactly under one of the outer phases ofthe power line. At a distance of about 35 m from the tower center,both the electric field and the charge per unit length drop to 50% oftheir maximum values. The electric field is found to increase almostlinearly with the clearance between the pipeline and the groundsurface. The charge changes in a more complicated way with theclearance. It decreases if the pipe clearance increases from 0 to 0.2m, then increases steadily beyond this value. For a given distancefrom the 750-kV line and for a fixed clearance from the ground,both the electric field and the electric charge per unit length on thepipeline will increase with the pipe radius.

This paper will deal also with the impact of the pipeline on thenearby EHV power line and its associated network. The results willshow that for a solidly earthed power network, the presence of thepipeline will be accompanied by a slight increase in the neutral cur-rent. On the other hand, for a power network with an inductivelyearthed neutral, there will be a tendency toward a parallel reso-nance that can occur for particular values of the neutral induc-tance and pipe radius. This resonance will result in an increase inthe system’s neutral potential, which will be primarily limited bythe network losses.

Index Terms—Capacitive coupling, electrostatic interference,extra high voltage (EHV) lines, pipelines.

I. INTRODUCTION

THE ever increasing cost for right of ways suitable forerecting extra high voltage (EHV) power lines and

pipelines as well as the noticeable current public awarenesstoward the visual and environmental impact of those lineshave led to exploring the possibility of using the close or evencommon corridors for both power and pipelines.

This, of course, reduces the land cost considerably. Neverthe-less, several technical problems will arise from the close prox-imity of those lines. One of those problems is the issue of inter-ference between the power and pipelines, during normal opera-

Manuscript received March 6, 2003.The author is with the Electrical Engineering Department, Kuwait University,

Safat 13060, Kuwait (e-mail: [email protected]).Digital Object Identifier 10.1109/TPWRD.2003.823211

tion as well as in emergency conditions [1]–[5], [8]. If we focuson the possible concerns regarding the effect of power lines onnearby pipelines, the electromagnetic coupling represents one ofthe possible reasons for endangering the personnel and equip-ment dealing with the pipelines. Basically, it has two compo-nents: inductive and capacitive. The first one is due to the mag-netic field generated by the currents in the power line. Since thiseffect is proportional to the line currents, steady-state magneticcoupling can assume dangerous values especially during faultconditions. The objective of [1], which is one of two volumesjointly issued by the Electric Power Research Institute (EPRI)and the Pipeline Research Committee (PRC) of the AmericanGas Association (A.G.A), was threefold: documenting availabledata on mutual interaction between electric power lines and par-allel natural gas pipelines, procedures for evaluating the powerfrequency voltages and currents electromagnetically induced onthe gas pipelines, and procedures to reduce these effects on bothcomponents and personnel. Reference [2] reports on a studydealing with a 525-kV power line, railroad, and pipeline sharinga common corridor for an exposure length of about 62 mi. Pri-mary concern was given to both the magnetic induction due tocurrent in the transmission line conductors (during normal andfaulty conditions) and the electrostatic induction due to voltageon these conductors. The impact on the safety considerationsfor railroad and pipeline operation or maintenance personnel aswell as on the compatible operation of electrical and electronicequipment associated with the pipeline and railroad system werediscussed. Two main criteria were suggested: the magneticallyinduced voltage to earth on an individual conductor, or the ac-cessible voltage difference between two conductors at an equip-ment location was limited to 60 V [5], and the electrostaticallyinduced available short circuit current to earth from a conductorwas limited to 6 mA.

In [3] and [4], a study specializing in the areas of inductiveand conductive coupling between power lines and natural gaspipelines was presented. A computer package, called ECCAPP,was described. Its problem-solving abilities and applications aredemonstrated. This paper summarizes also some of the resultsof parametric analysis examining the role of various factorsaffecting the electrical interference levels caused in pipelinesby nearby transmission lines under fault conditions. Reference[8] acknowledges that the problem of ac interference has beenknown for more than 30 years, and discusses the three typesof interference between ac lines and nearby pipelines: electro-static capacitive, resistive ohmic, and electromagnetic inductiveinterference. With regard to the capacitive component, the sig-nificance of grounding welded pipe sections lengths exceeding afew hundred to 1000 ft is discussed. It is further stated that withpractical pipe coating, this type of coupling is of minor signifi-cance after construction.

0885-8977/04$20.00 © 2004 IEEE

1226 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 19, NO. 3, JULY 2004

Fig. 1. Considered 750-kV, single-circuit, six-bundle transmission linetogether with the pipeline.

The presence of the pipelines will change the charge distribu-tion on the power line conductors as well as at the ground sur-face. The pipeline itself will be also electrically charged. Thenew charge distribution will depend on the geometrical data ofboth the power and pipelines, as well as on the separation be-tween them. Moreover, the charge and hence the field distri-bution will also depend on the neutral treatment of the powerline, since some of the system capacitive currents will have thecharacteristics of zero sequence components. Although the ca-pacitive coupling is basically a voltage-related phenomenon, itcan increase significantly during unsymmetrical faults becauseof the resulting asymmetrical voltages on the line conductors.

During sudden disturbances in either the electrical or thegeometrical arrangement, fast electromagnetic transient phe-nomena will take place involving both the capacitive as wellas the inductive coupling components simultaneously. Thispaper focuses on the steady-state capacitive coupling betweenthe electrical power line and a parallel pipeline sharing thesame corridor. The analysis will start with formulating therelationship between both the electric potential of the electricline conductors and the pipeline in terms of the conductors’charges using the concept of potential coefficients. As atypical example, the case of the exposure of a pipeline to a750-kV, three-phase, single-circuit, six-bundle EHV line willbe considered. For given phase voltages, the solution of a setof simultaneous linear equations will yield the charges on allsubconductors as well as on the earthed pipeline. It will thenbe possible to calculate the electrostatic field at any point ofinterest. Special attention will be paid to the maximum field aswell as the electric charge on the pipeline.

II. METHOD OF ANALYSIS

The analysis starts with giving the and coordinatesof the middle points of the three active bundled conductors

, and for the three phases , and, respectively. They give the centers of the circles passing

through the subconductors of the respective phases. Requiredalso are the coordinates locating the center of thepipeline; see Fig. 1.

The next step is to derive the coordinates of all the 18 subcon-ductors (6 for each phase) in terms of the coordinates of theircorresponding middle point, the radius of the bundle circuit ,and the radius of each subconductor. For example, the coordi-nates of the subconductors of phase a, numbered from 1 to 6,can be given by Table I. The coordinates of the subconductors(7, 8, 12) corresponding to phase can be obtained using

TABLE ICOORDINATES OF THE SUBCONDUCTORS OF PHASE a

Fig. 2. Distances between the conductors m;n.

TABLE IIABSOLUTE POTENTIALS OF CONDUCTORS

Table I after putting , and instead of and . Similarly,the coordinates of subconductors (13, 14, 18) can be derivedby replacing and in Table I by and , respectively.With the coordinates of the conductors, it is possible tocalculate the distances between any two conductors by

(1)

Moreover, the distance between the conductor and mirror ofthe conductor (denoted ) with respect to the ground surfaceis

(2)

as depicted in Fig. 2.Using the above distances among the actual conductors and

their images with respect to the ground surface, it is possible todetermine the potential coefficients as given in [6], [7].

The absolute potentials of the different conductors are shownin Table II. The values in Table II are given assuming that theline is a part of a solidly earthed neutral network. denotes thepeak phase voltage V, with the voltageof phase taken as a reference for all phasor quantities.

SAIED: CAPACITIVE COUPLING BETWEEN EHV LINES AND NEARBY PIPELINES 1227

Fig. 3. Field components at the point P of (x; y) due to Q and its image�Q .

A system of simultaneous complex equations can then be for-mulated linking the charges on the conductors aswell as on the image conductors with the givenvoltages, in terms of the different potential coefficients.

The above system of equations can be easily reduced to a sim-pler one since the charges of the image conductors are exactlythe negative values of those existing on the conductors. It wasthen possible to use a Mathematica program to solve these equa-tions in order to get the complex charges , andtheir images.

The capacitive current through any conductor is equal to. Accordingly, the capacitive currents through the different

phases are

(3)

The neutral current is then

(4)

Having determined the individual complex charges , it is pos-sible to determine the electric fields at any arbitrary point dueto and its image-

and (5)

in the directions indicated in Fig. 3, where

(6)

In order to get the resultant electric field due to and ,both the horizontal and vertical components of and ,should be determined and added. This process will be repeatedfor all charges and the corresponding negative images in orderto get the total electric field at any point of coordinates .

It should be noted that the so-determined electrostatic fieldsare two-dimensional, and have no axial or longitudinal compo-

nents, since the issue of the electromagnetic or inductive cou-pling is not taken into account.

Two approaches will be used in order to demonstrate the im-pact of the pipeline on the high voltage power line. The first ap-proach deals with results describing the effect of the presence ofthe pipeline on the electric potential distribution in the vicinityof the power line. Several graphs illustrating the pipeline sur-face gradient will also be presented. They will enable us to as-sess these gradient in comparison with the typical values of theundisturbed field on the surfaces of the active phase conductors,on the ground wires, and on the ground surface. The second ap-proach is based on a circuit analysis comprising impact of thepipeline on the values of both the potential assumed by the neu-tral point and the current through the earthing impedance (if ap-plicable), for different kinds of neutral treatment.

III. RESULTS

The above method is applied to a 750-kV single-circuit,50-Hz, six-bundle overhead transmission line with flat hor-izontal conductor configuration. The line has the followinggeometrical data:

• radius of each bundle subconductor cm;• average height of the active 18 subconductors m;• -coordinate of the center of phase ;• -coordinate of the center of phase m;• -coordinate of the center of phase m;• radius of the circle passing through subconductors

cm.The coordinates and geometrical data of the pipeline will begiven later for each case study.

Several computer runs have been done to validate the de-scribed model. The potential at the ground level wascomputed and plotted as a function of the horizontal coordinate

. The potential was found constant . Then the horizontalcomponent of the electric field was computed along the samepath and found also to be zero, as expected. At any active con-ductor, the potential was calculated and found to be equal to thecorresponding phase voltage. The neutral current (per unitlength) of the power line can then be obtained using (4). As-suming a neutral impedance , the neutral voltage is

(7)

First, a pipeline of radius 0.5 m is assumed. Its axis is 1 m abovethe ground level, and is at a horizontal distance 35 m to the rightof phase .

Fig. 4 is given to illustrate the impact of the pipeline on the po-tential distribution around the EHV power line. The -axis givesthe coordinate, in meters, measured from phase a. The distribu-tions are shown for four horizontal planes with the indicated ver-tical distances. The originally symmetrical curves (with respectto m of phase b) will be strongly distorted by the pres-ence of the pipeline. All four curves are seen to be pulled downin the vicinity of m in order to satisfy the condition ofzero potential of the earthed pipeline. The potential distributionalong two vertical planes at horizontal distances 34.5 m (i.e.,touching the left side of the pipe) and 35.5 m (i.e., touching theright side of the pipeline) is indicated in Fig. 5. The two curves


Fig. 4. Potential distribution along four horizontal planes (with the indicatedheights above ground). The x-axis gives the coordinate in meters measured fromphase a.

Fig. 5. Potential distribution in kilovolts (max) along two vertical planes ofthe indicated horizontal distances in meters, measured from phase a.

give the electric potential versus the height in meters measuredfrom the ground level.

In the absence of the pipeline, the two curves will be nearbystraight lines (for heights between 0 and 2.5 m). Again here, thepresence of the pipeline will distort the potential distributionin the way depicted in Fig. 5, in order to satisfy a zero pipepotential (at m for both curves).

Fig. 6 depicts the (vertical) field distribution on the groundsurface versus the -coordinate in meters measured from phase

. The originally symmetrical distribution of the field magnitudewill be modified indicating the strong shielding effect of theearthed pipeline, hi particular, beneath the pipe. The field is seento reverse its direction, so that there will be two locations (i.e.,two parallel straight lines) on the ground surface having zeroelectric field.

These zero-field parallel lines correspond, approximately, tothe intersections of the two vertical planes mentioned in the con-text of Fig. 5 with the ground surface. Directly under the axis ofthe pipelines, the field reverses its sign and drops in magnitudefrom about 0.07 kV/cm (as seen from Fig. 6 at m)to about 0.03 kV/cm.

The distribution of the electric field on the pipe surface isillustrated in Fig. 7. The field in kilovolts (max)/cm is given independence on the angle measured from the positive directionof the horizontal -axis. The field direction is always normalto the surface of the pipeline. The curve is indicating that the

Fig. 6. Effect of the pipeline on the electric field distribution on the groundsurface.

Fig. 7. Electric field on the pipe surface as a function of the angle measuredfrom the direction of the positive x-axis.

Fig. 8. Electric field at the top of the pipeline as a function of the pipe’shorizontal distance measured in meters from the tower center.

field on the pipe upper surface is much stronger than that of thelower half. At an angle of 90 (i.e., on the top of the pipeline),the field is 0.148 kV/cm, whereas at an angle of 270 (i.e., atthe pipe bottom), the field is 0.06 kV/cm. This is because boththe earthed pipeline and the ground have zero potential.

The dependence of the maximum pipe electric field (i.e., onthe top of the pipeline) on the horizontal distance between thepipe and the tower center is given in Fig. 8. The maximum elec-tric field has its highest value of about 0.175 kV/cm if the pipeis placed at m measured from phase b. The field thendecreases steadily to almost zero if the pipeline is about 100 mfar from the tower center (or phase ). These values assume con-stant pipe radius (0.5 m) and height (1 m).


Fig. 9. Charge/meter on the pipeline versus its horizontal distance from thetower center.

Fig. 10. Charge/meter on the pipeline as a iunction of the pipe clearance toground.

A similar behavior is seen in Fig. 9 depicting the relationshipbetween the magnitude of the charge per meter on the pipeline(in 10 C/m) and its separation from the tower center. Againhere, the charge on the pipe will be extremely small if the pipeis placed at a distance of more than 100 m (for the given piperadius and height).

The effect of the clearance between the pipe bottom and theground (in meters) on the charge on the pipeline (in 10 C/m)is depicted in Fig. 10. If the pipe (of 0.5 m radius) is almosttouching the ground surface (i.e., zero clearance), a charge of2.8 10 C/m will result. Increasing the clearance from zerowill be accompanied by a decrease of the charge, until it assumesits least value of 2.6 10 C/m at a clearance of about 0.2 m.The charge then increases steadily with the clearance, reaching3.52 10 C/m at a clearance of 1.3 m. The pipe radius isunchanged m and is located at a fixed distance 23 m fromthe tower center.

As for the maximum electric field on the top of the pipeline,so for clearances less than 0.15 m, the field will remain al-most constant 0.132 kV/m. As the clearance increases beyond0.15 m, the field increases almost linearly to reach about 0.180kV/cm at a clearance of 1.3 m.

Changing the radius of the pipeline will affect the charge perunit length as shown in Fig. 11. Here, it is assumed that both theheight and the horizontal distance of the pipe from the towercenter are fixed, namely 1 and 23 m, respectively. For pipe radii

Fig. 11. Charge/meter on the pipeline as a function of its radius.

Fig. 12. Effect of the pipeline radius on its maxim electric field.

less than 0.65 m, the charge/meter increases almost linearly withthe radius. Beyond 0.65 m, the charge increases at a faster rate.

The effect of the pipe radius on the maximum electric field(at the top of its surface) is given in Fig. 12, in which the radiusvaries between almost zero to 1 m. It is noticed that the fieldassumes large values for small pipe radii. From Fig. 6, it couldbe seen that at a point 23 m from the tower center the magnitudeof the undisturbed field at the ground level in the absence ofthe pipeline will be about 0.07 kV/cm. Fig. 12 shows, however,that a pipe of a radius of 0.5 m placed at the same location willassume a maximum electrostatic field of about 0.15 kV/cm (i.e.,more than double the value of the undisturbed field). Since theclearance to ground is assumed fixed (1 m), pipelines of radiigreater than 1 m could not be represented in Fig. 12.

In the following part, the impact of the pipeline on the EHVpower line will be investigated. The considered power line is apart of a solidly earthed network and the axis of the pipeline isassumed 2 m above the ground level.

The neutral current in mA/km, as obtained using (4), will bediscussed. In the absence of the pipeline, i.e., its radius is zero,the neutral current is 194 mA/km. This “intrinsic” neutral cur-rent is due to the unsymmetrical flat conductor configurationof the intransposed power line. The presence of the pipeline in-creases the neutral current slightly. The effect increases with thepipe radius. For a pipe radius of 2 m, the neutral current will in-crease only by about 1.8% to reach 197.5 mA/km.

Without any loss of generality, and in order to reduce thecomputational burden, the following results refer to a simpler750-kV, two-phase power line with flat configuration, i.e., theconductors of the two phases and have the same height


Fig. 13. Equivalent circuit used for calculating the neutral potential V andthe neutral current I .

Fig. 14. Neutral current, in amps per meter for a 750-kV, two-phase line as afunction of the pipe radius. The EHV network is assumed solidly earthed.

above ground, 20.2 m. Furthermore, no bundling is considered.Each of the two phases has a single solid circular conductor of35.8–cm radius (which is chosen equal to the geometrical meanradius of the previously considered three-phase line). The con-ductors of phases and are assumed 11.8 m apart. The pipelineis assumed located at a horizontal distance of 11.2 m to the rightof the power line. The phase voltages of the two-phase line are

750 2 and 750 2 kV for phase and , respectively. Fig. 14depicts the effect of the pipe radius on the neutral current for theuntransposed two-phase line, in amps per meter.

Here, in the absence of the pipeline (i.e., its radius is zero),the neutral current is zero. There is no “intrinsic” neutral currentbecause the two-phase line with its flat conductor configurationis geometrically symmetrical with respect to the ground surface.In the presence of a pipeline of a radius 2 m, and placed 2 mabove ground, this symmetry will be disturbed, resulting in aneutral current of about 10 A/m or 10 mA/km.

Another situation for a possible adverse effect of the pipelineon a nearby power network assumes a compensated network,i.e., a network inductively earthed via Petersen coils (i.e.,

in Fig. 13). These inductors are used to compensate for thestray capacitive currents during earth faults and hence facilitatethe duty of the circuit breakers involved. Since the stray capac-itances increase with the network geometrical dimensions, therequired inductive reactance will decrease with the line length.Fig. 15 depicts a three-dimensional plot giving the magnitudeof the steady state neutral voltage, in volts, as a function of

Fig. 15. Neutral voltage V as a function of both the neutral reactance (in�m) and the pipe radius (in meters) of a compensated network.

Fig. 16. Plot illustrating the parallel resonance which will occur at a certainvalue of the neutral reactance, due to the presence of a parallel pipeline of radius1 m.

both the radius of the pipeline in meters and the reactance of theneutral reactance in meters. It is seen that even in the absenceof the pipeline (i.e., for a pipe with almost zero radius) thereis a particular value of the neutral inductive reactance (about1.7 10 m) at which parallel resonance occurs. This willbe accompanied by a considerable displacement of the neutralvoltage. The presence of the pipeline is seen to “detune” the par-allel resonance, i.e., the resonance will occur at smaller valuesof the neutral inductance. This can be attributed to the fact thatthe pipe will increase the effective network capacitance. There-fore, smaller inductance will be needed for a parallel resonanceto occur at the power frequency.

This effect increases with the pipe radius as see in Fig. 15. Theneutral voltage during this situation will be limited primarily bythe network losses.

Theoretically, this voltage can reach an infinite value, if thenetwork is assumed lossless, as seen in Fig. 16, giving the neu-tral voltage for the case of a pipe of 1 m radius placed 2 m aboveground, in terms of the power network’s neutral reactance .

Fig. 17 depicts the magnitude of the neutral voltage for a par-ticular neutral reactance of the power network 1.51 10 mas a function of the pipe radius. It is seen that there is a criticalvalue for the radius of the pipeline (around 1.8 m in this case) atwhich the neutral voltage will assume dangerously high values(limited by the network losses). Since the losses are not takeninto consideration in its analysis, Fig. 17 shows an infinite neu-tral voltage for this critical pipe radius.


Fig. 17. Neutral voltage versus the pipe radius for a particular neutralreactance.

IV. CONCLUSION

1) The problem of the mutual capacitive coupling betweenEHV power lines and nearby pipelines sharing the samecorridor is pointed out. The issue is of paramount signif-icance especially in oil-producing countries such as theGulf states.

2) A mathematical model is given for the computation ofthe electrostatic effect of the power line on the pipelines.Two indexes are used to assess this effect: the maximumelectrostatic field and the electric charge per unit length ofthe pipe. The impact of the pipeline on the potential andfield distributions around the power line is also discussed.

3) For a 750-kV, three-phase power line, and a pipeline of aradius 0.5 m, it is seen that the electric field on the pipe canreach 0.175 kV/cm, for a horizontal separation of about16 m between them. Both the field and the charge on thepipe will decrease to almost zero if the pipeline is 100 mfrom the power line.

4) The relationship between the pipe charge and the clear-ance between the pipeline and the ground is rather com-plicated. Increasing the clearance from zero will be ac-companied by a decrease of the charge, until it assumes itsleast value of 2.6 10 C/m at a clearance of about 0.2m. The charge will then steadily increase with the clear-ance, reaching 3.52 10 C/m at a clearance of 1.3 m.

5) For clearances less than 0.15 m, the field on the pipesurface will remain almost constant 0.132 kV/cm. Asthe pipe clearance increases beyond 0.15 m, the field in-creases linearly with the clearance, reaching about 0.180kV/cm at a clearance of 1.3 m.

6) For pipe radii less than 0.65 m, the charge/m on thepipeline increases almost linearly with the radius. Be-yond 0.65 m, the charge increases at a faster rate.

7) Several parameter studies have been done to investigatethe impact of the pipelines on the EHV power line. It isnoticed, for example, that the presence of the pipeline willresult in a slight increase (around 1.8%) in the neutralcurrent, if the power line is part of a solidly earthed powernetwork.

8) For the case of inductively earthed neutral, the results ofanalyzing a case involving a 750-kV, two-phase powerline show that even in the absence of the pipeline, thereis a particular value of the neutral inductance at whichparallel resonance will occur, accompanied by a consid-erable shift of the network’s neutral voltage. The pipelinewill detune the parallel resonance, i.e., the resonancewill occur at a smaller neutral inductance. This effectincreases with the pipe radius.

9) Results show also that for a particular power network’sneutral inductance, there will be a critical value for thepipe radius, at which the above mentioned resonance phe-nomenon will occur. On the other hand, there exists a crit-ical neutral reactance that will result in this resonance fora given pipeline radius.

REFERENCES

[1] J. Dabkowski and A. Taflove, “Mutual design considerations foroverhead ac transmission lines and gas transmission pipelines,” ElectricPower Research Institute (EPRI), Volume 1: Engineering Analysis,Sept. 1978.

[2] M. Frazier, P. Thomas, H. Roberton, J. Dunlap, and T. Morgan, “Trans-mission line, railroad and pipeline common corridor study,” IEEE Trans.Power Delivery, vol. PWRD-1, pp. 294–300, July 1986.

[3] F. P. Dawalibi and R. D. Southey, “Analysis of electrical interferencefrom power lines to gas pipelines—Part I: Computation methods,” IEEETrans. Power Delivery, vol. 4, pp. 1840–1846, July 1989.

[4] , “Analysis of electrical interference from power lines to gaspipelines: Part II: Parametric analysis,” IEEE Trans. Power Delivery,vol. 5, pp. 415–421, Jan. 1990.

[5] , Principles and practices for inductive coordination of electricsupply and railroad communications/signal systems, Association ofAmerican Railroads and Edison Electric Institute, Sept. 1977.

[6] Transmission Line Reference Book, 345 kV and Above, 1982.[7] J. A. Grainger and W. D. Stevenson, Power System Analysis, 1st

ed. New York: McGraw-Hill, 1994, ch. 5.[8] J. Smart III, D. van Costendrop, and W. Wood, “Induced AC creates

problems for pipelines in utility corridors,” J. Corrison Technol., vol.82, no. 6, pp. 1–12, June 1999.

Mohamed M. Saied (M’80–SM’84) was born in Egypt in 1945. He receivedthe B.Sc. degree (Hons.) in electrical engineering from Cairo University, Cairo,Egypt, in 1965 and the Diplom-Ingenieur and Doktor-Ingenieur degrees fromRheinisch-Westfaelische Technische Hochschule (RWTH), Aachen, Germany,in 1970 and 1974, respectively.

From 1965 to 1967, he was a Research and Teaching Assistant at Cairo Uni-versity. From 1974 to 1983, he was a Faculty Member at Assiut University,Egypt. In 1983, he joined Kuwait University, Safat, Kuwait, where he is now afull Professor of electrical power engineering. He spent a one-year sabbaticalleave (1998) as a Visiting Professor at Cairo University.

Prof. Saied is a Senior Member of Forschungs-Gesellschaft Energie in Ger-many and CIGRE’ in France.

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The Capacitive Coupling Between EHV Lines and Nearby Pipelines - IEEE