* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Electric and magnetic fields produced by 400kv double circuit
Neutron magnetic moment wikipedia , lookup
Field (physics) wikipedia , lookup
Magnetic field wikipedia , lookup
Electrostatics wikipedia , lookup
Maxwell's equations wikipedia , lookup
Magnetic monopole wikipedia , lookup
History of electromagnetic theory wikipedia , lookup
Condensed matter physics wikipedia , lookup
Lorentz force wikipedia , lookup
Electromagnetism wikipedia , lookup
Electromagnet wikipedia , lookup
Electric and magnetic fields produced by 400kv double circuit overhead lines – Measurements and calculations in real lines and line models Evangelos I. Mimos*, Dimitrios K. Tsanakas, Antonios E. Tzinevrakis Department of Electrical and Computer Engineering, University of Patras, Greece Abstract: 1. Introduction In this paper, the results of systematic measurements and comparative calculations of the electric and magnetic fields in the vicinity of two parallel running 400kV double circuit power lines of the Greek transmission system are presented. The measurements were conducted during the operation of the lines with the usual symmetrical phase conductor arrangement as well as after the application of the optimum phase conductor arrangement for the electric and magnetic field minimization. Overhead high and extremely high voltage lines are often a cause of public concern about possible effects of the produced electric and magnetic fields on health. Until recently, the limit values of the field intensities (reference values) for public exposure for the 50Hz frequency were common in ICNIRP guidelines [1] and in the European Union Council Recommendation [2]. These limit values were 5kV/m for the intensity of the electric field and 100μT for the magnetic flux density. For occupational exposure the corresponding values in guidelines [1] and the Directive of European Parliament and Council [3] were 10kV/m and 500μT. In December 2010, ICNIRP published its new guidelines [4]. The new reference values for the magnetic flux density are for public exposure 200μΤ and for occupational exposure 1000μT. The reference values for the intensity of the electric field remain the same. ICNIRP has also published a fact sheet which explains the reasons why reference values of the magnetic flux density have been increased. In 2013 the new reference values of ICNIRP [4] for the occupational exposure were adopted by the new Directive of European Parliament and Council [5]. Measurements were also conducted in the vicinity of a model of the power lines. The design and construction of the power line model was an interesting technical task. The model dimensions must be large enough so that, given the size of the instruments, measurement of the fields in the vicinity of the model depictures the situation in the vicinity of real lines. The electrical supply system has been designed so that the line currents are large enough to create equal levels of the magnetic field as in the vicinity of real power lines. Special equipment is needed for power supply and current control for the application of different phase arrangements. The measurements in the vicinity of real lines confirmed the drastic reduction of the electric and magnetic field levels after the application of the optimum phase conductor arrangement. The measurements in the vicinity of models and the computational investigations led to the same result. The phase conductor arrangement of double circuit lines is an important factor on the produced electric and magnetic field. Until few years ago, 400kV double circuit power lines of the Greek transmission system were constructed with the symmetrical phase arrangement. A series of *[email protected] KEYWORDS Calculations, double circuit lines, electric and magnetic fields, measurements, overhead, power line models. Cigre Science & Engineering • N°5 June 2016 28 Figure 1: Arrangements of the 400 kV double circuit parallel running lines. a) Symmetrical phase arrangements on line (1) and line (2) b) Optimum phase arrangements on line (1) and line (2) c) Towers of line (1) and (2) theoretical studies, such as [6]–[10], showed that this arrangement was not optimum as far as the reduction of electric and magnetic fields is concerned and proposed another phase arrangement as the optimum one. New 400kV double circuit power lines in Greece are now being constructed with the optimum phase arrangement for the minimization of electric and magnetic fields. The optimum phase arrangement is also being applied to existing 400kV double circuit power lines (with the symmetrical phase arrangement). The application of the optimum phase arrangement to an existing double circuit line is an easy process, which is achieved by proper interchanging of the phase conductors at both ends of the line. In the current paper, measurements of electric and magnetic fields are presented before and after the application of the optimum arrangement in real 400kV double circuit transmission lines. Electric and magnetic field measurements in the vicinity of power lines are also presented in [11]–[17]. In [18], the minimization of electric and magnetic fields in the planning and design of transmission lines is examined. BAC|B’A’C’ BAC|C’A’B’ BAC|B’A’C’ BAC|C’A’’B double circuit lines has been developed and constructed at the Power Systems Laboratory of the University of Patras in order to investigate experimentally the effect of the many possible phase conductor arrangements on the produced electric and magnetic fields. Power line models have also been developed in [19]–[21]. The measurements and calculations in the vicinity of real lines and line models confirm the drastic reduction of electric and magnetic field levels due to the application of the optimum phase conductor arrangement. 2. Measurements in the vicinity of real 400kV double circuit power lines In order to confirm the ability of the optimum phase arrangement of conductors to reduce electric and magnetic fields produced by 400kV double circuit power lines, measurements were performed before and after the application of the optimum arrangement in the vicinity of two parallel running 400kV double circuit power lines. Figure 1a shows the symmetrical phase arrangement before the application and Figure 1b shows the new optimum phase arrangement which was applied to the power lines. Figure 1c shows the dimensions of the towers in both power lines. The various phase arrangements for the reduction of electric and magnetic fields cannot be tried on real operating lines. Power line models offer the ability to confirm experimentally the results of theoretical investigations of the electric and magnetic field. A model of one line and two parallel running 400kV Cigre Science & Engineering • N°5 June 2016 29 Figure 2: Changes required for the application of the optimum phase arrangement on a double circuit transmission line a) Symmetrical phase arrangement (before) b) Optimum phase arrangement (after). Changes are marked with dashed lines. shown in Figure 1c. The lines are equipped with twin phase conductors of 2x954 MCM (2x483mm2) cross section. The separation between the two sub-conductors is 40cm. The ground wires are equipped with steal conductors of 190 MCM (96,47mm2). Figure 2 shows the changes required for the application of the optimum phase arrangement to an existing double circuit power line. Figure 2 shows one double circuit line and the portals of the line at the substations SΙ and SII. In Figure 2a the symmetrical phase arrangement is applied and in Figure 2b the optimum phase arrangement. Only the conductors of one circuit are shown in Figure 2 but the locations of both circuits’ conductors are shown. The measurements were performed with the Standard EMDEX II meter of ENERTECH Consultants [22] complying with IEC Standard 61786 [23] and the IEEE Standard 644-1994 [24]. The typical measurement accuracy of the EMDEX II meter is ±1% for the magnetic flux density and ±5% for the intensity of the electric field. In order to switch from the symmetrical arrangement to the optimum one, only simple changes and only for one of the two circuits of the lines are necessary. The optimum arrangement is obtained by interchanging the conductors of phases B’ and C’ at the parts of the line between the fist tower T1 and the substation SI and between the last tower Tn of the line and the corresponding substation SII. The application of the same optimum arrangement on each double circuit line leads to an overall optimum arrangement for parallel running lines, [6]–[8]. At the measurement area the distance of the lower conductors of line (1) from the ground is h(1)=21,8m and the corresponding distance for line (2) is h(2)=23,8m. The currents were I(1)=I(2)=99A per phase and circuit for the measurements during the symmetrical phase arrangement and I(1)=I(2)=114A during the optimum phase arrangement. The measured values have been also verified computationally. The computer software that was used is based on the numerical calculation of the field intensities as the vectorial sum of the field intensities produced by each conductor separately. This Figure 3 shows the measured values of the intensity of the electric field and the magnetic flux density for the two parallel running lines (1) and (2) with their phases arranged according to Figure 1a and Figure 1b. The tower type and the distances between the conductors are Cigre Science & Engineering • N°5 June 2016 30 Figure 3: Measured and calculated values of the electric strength E and the magnetic flux density B as a function of the distance x (indicated in Figure1) measuredcalculated Before, symmetrical arrangement BAC|B’A’C’ BAC|B’A’C’ X X X X ______ After, optimum arrangement BAC|C’A’B’ BAC|C’A’B’ ∙ ∙ ∙ ∙ ----- is a typical method for the calculation of field intensities produced by power lines [25], [26]. The same software has been used for the calculation of the magnetic flux density in [27], [28] and the intensity of the electric field in [29], [30]. The deviation of the maximum values between measurements and calculations for the intensity of the electric field comes up to about 6,66-15,5% taking into consideration the typical accuracy of the measurement meter and is mainly due to the distortion of the electric field by nearby objects (vehicles, houses, trees). The deviation of the magnetic flux density values is much smaller and is due to the change of the line current during measurements. theoretical investigations a model of two parallel running 400kV double circuit lines has been constructed. 3.1. Operating principle of the model Figure 4a shows the magnetic flux density at a point of interest P produced by a conductor of a real power line, either phase conductor or ground conductor, and Figure 4b the magnetic flux density produced by a corresponding conductor of the power line model. Figure 3 confirms the effective reduction of the field intensities by the application of the optimum arrangement. For example, the maximum measured value of the intensity of the electric field is limited from 3,04kV/m to 1,35kV/m and the magnetic flux density from 0,65μΤ to 0,38μΤ (reduction to its 40,2-49,1% and 57,3-59,6% respectively). Figure 4: Magnetic flux density at a point of interest P a) Produced by a real conductor with current Ii The relatively low values of the magnetic flux density are due to the relatively low load of the lines during measurements (about 100A per circuit and phase). Loading with the tenfold current will increase by ten the magnetic flux density. b) Produced by a model conductor with current Imi at the point of interest P The magnetic flux density produced by the real power line is given by the general relation [25], [26]: 3. Measurements in the vicinity of a model of 400kV double circuit power lines where μ0=4π·10-7 H/m is the magnetic permeability of free space, Ii is the current of the conductor i and is the vector distance of point P to the conductor i. The magnetic flux density at point P produced by the power line model is given by: The various phase arrangements for the reduction of electric and magnetic fields cannot be tried on actual operating lines. A model of the power line is an alternative for these trials. In order to confirm experimentally the Cigre Science & Engineering • N°5 June 2016 31 The intensity of the electric field at point P produced by the real power line is given by the general relation [25], [26]: where Imi is the current of the model conductor i and is the vector distance of point P to the model conductor i. If the distance of the model conductor is Kl times smaller than the distance of the real conductor (geometric scale model 1: Kl) and the current of model conductor is KI times smaller than the current of the real conductor (current scale model 1: KI) then where ε0=(1/36π).10-9 F/m is the electric permittivity of free space, Qi is the electric charge of the conductor i and is the vector distance from point P to the conductor i. The charge Qi of the conductor i is given by and where The magnetic flux density from the real power line, given in (1) can be rewritten as: V1, V2,… Vn are conductors’ voltages and the terms sii and sij are given by If the constant Kl is equal to the constant KI, then the magnetic flux density of the power line model is equal to . the magnetic flux density of the real power line, where hi , ri , dij, d'ij are: Figure 5 shows the intensity of the electric field at the point of interest P produced by the conductor of a real power line, either phase conductor or ground conductor, (Figure 5a), and the intensity of the electric field produced by the conductor of the power line model (Figure 5b). hi , the height of the conductor i above ground ri , the radius of the conductor i dij, distance between the conductors i and j d'ij, distance between the conductor i and conductor’s j image. The intensity of the electric field at point P produced by the power line model is given by: where Qmi is the electric charge of the model conductor i and is the vector distance from point P to the model conductor i. Figure 5: Intensity of the electric field The charge Qmi of the model conductor i is given by at a point of interest P a) Produced by a real conductor with charge Qi b) Produced by a model conductor with charge Qmi Cigre Science & Engineering • N°5 June 2016 32 where Vm1, Vm2,… Vmn are the model conductors’ voltages and the terms smii and smij are given by Therefore, replacing (18) and (19) in (7) the charge Qi results where hmi , rmi , dmij, d'mij are hmi , the height of the model conductor i above ground Using (14) and (20) the intensity of the electric field from the real power line can be rewritten as: rmi , the radius of the model conductor i dmij , distance between the model conductors i and j d'mij , distance between the model conductor i and model conductor’s j image. If every distance (radius, height above ground, distance between conductors) of the model conductor is Kl times smaller than the distance of the real conductor (geometric scale model 1: Kl) and the voltage of the model conductor is Kv times smaller than the voltage of the real conductor (voltage scale model 1: Kv) then If the constant KV is equal to the constant Kl, then the intensity of the electric field of the power line model is equal to the intensity of the electric field of the real . power line, 3.2. Construction of the model The dimensions of the model must be enough so that, given the size of the instruments, measurement of the fields in the vicinity of the model depictures the situation in the vicinity of real lines. Models with small dimensions lead to a relatively large measurement error due to the size of the sensors of EMF meters. Models with large dimensions have economical and spatial constraints. The 1:16 scale emerged as the best scale for the model of lines taking into account the space available and the requirements of accurate measurements. The dimensions of the tower of a real line are given in Figure 1c. The dimensions of the model are 12m (length), 3.2m (width) and 3.6m (height). The distance between the model lines is 2,19m. Figure 6 shows a photograph of the model. In the power line model the ground conductors have been placed above the phase conductors in correspondence with the real line. The model towers are wooden in order to avoid distortions of the field intensities. and Taking into consideration (16) and (17) the following relations arise Cigre Science & Engineering • N°5 June 2016 33 Figure 7: Diagram with equipment for the electrical supply of the model lines. * Connections for applying different phase arrangements may be chosen between 6 steps of 10,2V, from 10,2V to 6x10,2V = 61,2V. The current on the secondary circuit may come up to 500A. There is also the ability to divide the winding of each phase of the secondary circuit and connect the halves in parallel, in order to achieve currents up to 1000A. For the adjustment of the desired currents on the lines, beside the choice of the secondary circuit voltage, reactance coils without iron core are used. These coils had to be carefully winded so that the line currents are balanced. Also two special switchboards were needed in order to control the operation and to be able to change the phase arrangements on the two lines. The switchboards are also equipped with current and voltage measurement instruments as well as short circuit and ground fault protecting equipment. The main switchboard and the two special switchboards are presented in Figure 7. The electric equivalent circuit of the model lines with the supply equipment is given in Figure 8. 3.3. Measurement results Figure 9 shows characteristic measurement results in the vicinity of the model lines and relevant comparative calculations. Figure 6: The model of the two parallel 400kV lines under 1:16 scale The electrical supply system must be designed so that the line conductors carry current large enough to create equal levels of the magnetic field as in the vicinity of real power lines. The model lines are equipped, as real 400kV power lines, with twin phase conductors, with loading capability up to 200A per phase and circuit. This current corresponds to a load of real lines 200Α x 16=3200Α. The distance between the lower conductors of the model lines and the measurement and calculation level is 1,25m, which corresponds to 1,25mx16=20m in the vicinity of a real line. The axis x is not the distance from the model line but the corresponding distance in the vicinity of a real line, which is 16 times higher. The current during measurements was 185A per circuit and phase, which corresponds to 185Ax16 = 2960A current of the real line. The measurement values given in Figure 9 are normalized to 1000A per circuit and phase actual line current, so that the magnetic flux density values correspond to actual values under 1000A loading. The lines are supplied through two transformers (one for each line) which were designed especially for this purpose. These high current transformers have a nominal power of 50kVA each and are connected to the 220/380V main supply. The polar voltage of the secondary circuit Cigre Science & Engineering • N°5 June 2016 34 Figure 8: Electric equivalent circuit of the model lines with the supply equipment. Values in mΩ. Outside brackets the values are given at 20oC, within brackets in operating temperatures. For this normalization, the measured values have been multiplied by the factor 1000Α / 2960Α =0,338. Thus, it is possible to reach conclusions about the field levels appearing in the vicinity of real lines, based on the model measurements. accuracy. The measured values are not symmetrical to the axis of the arrangement because the field at the right of line (1) is affected by the fields produced by nearby equipment (reactance coils, switchboards). Using the power line model it is possible to try various scenarios of arrangements and loadings that would be difficult to try on real lines. For example, comparing Figure 9a and Figure 9b, it is concluded that the parallel running of two or more equally loaded double circuit lines does not practically affect the maximum values of the field intensities in comparison with one double circuit line alone. Figure 9a shows the magnetic flux density in the case that only the one line is loaded, that is line (1). Using the optimum phase arrangement an overall reduction of the magnetic field levels is achieved. The maximum measured value is reduced from 6,4μΤ to 3,9μΤ (reduction from 59,7% to 62,2% according to meter accuracy). The corresponding reduction at the right of way limit is significantly higher, reduction from 4,3μΤ to 1,7μΤ (reduction from 38,8% to 40,3% according to meter accuracy). 4. Conclusions The phase arrangement of double circuit lines is an important factor on the produced electric and magnetic fields. New 400kV power lines in Greece are being constructed with the optimum phase arrangement for the minimization of the field intensities. The optimum phase Figure 9b shows the magnetic flux density in the case where both lines are loaded. The overall reduction of the magnetic field levels, caused by the optimum phase arrangement, is observed. The maximum measured value is reduced from 46,6% to 48,5% according to meter Figure 9: Measured and calculated values of the magnetic flux density B in the vicinity of the model Cigre Science & Engineering • N°5 June 2016 35 arrangement is also being applied to existing 400kV double circuit power lines with the symmetrical phase arrangement. The application of the optimum phase arrangement to an existing double circuit line is an easy process, achieved by proper interchanging of the phase conductors at both ends of the line. agents (electromagnetic fields) (18th individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC),” pp. L184/1-L184/9, May 2004. [4] International Commission on Non-Ionizing Radiation Protection, “Guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic fields (up to 300GHz),” Health Physics, vol. 99, issue 6, pp. 818 -836, Apr. 2010. [5] European Parliament and Council, “Directive 2013/35/EC of 26 June 2013, on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields) (20th individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC) and repealing Directive 2004/40/EC,” pp. L179/1-L179/21, Sep. 2013. Measurements of electric and magnetic fields before and after the application of the optimum arrangement in real lines verified the drastic reduction of the field intensities. Also, the application of the same optimum arrangement on each double circuit line leads to an overall optimum arrangement for the parallel running lines. [6] D.Tsanakas, D. Tsalemis, D. Agoris and J. Vojazakis, “Optimum arrangements of the phase conductors of overhead transmission lines for the magnetic field minimization,” CIGRE Rep. 36-101, Paris, France, 1994. Power line models offer the ability to confirm experimentally the results of theoretical investigations for the electric and magnetic field. The model dimensions must be large enough so that, given the size of the instruments, measurements of the fields in the vicinity of the model depictures the situation in the vicinity of real lines. The electrical supply system must be designed so that the line conductors’ currents are large enough to create equal levels of the magnetic field as in the vicinity of real power lines. Special equipment is needed for power supply and current control for the application of different phase arrangements. The chosen scale for the two parallel 400kV double circuit model lines occurred 1:16. [7]Cigre Working Group 22.14, “High voltage overhead lines Environmental concerns, procedures, impacts and mitigations,” Technical Brochure No. 147, Oct. 1999. [8] D. Tsanakas, G. Filippopoulos, J. Voyazakis, and G. Kouvarakis, “Compact and optimum phase conductor arrangement for the reduction of electric and magnetic fields,” CIGRE Rep. 36-103, Paris, France, 2000. [9] CIGRE WG B2.06, “The Influence of Line Configuration on Environment Impacts of Electrical Origin,” CIGRE Technical Brochure 278, Aug. 2005. [10]CIGRE WG C4.204, “Mitigation Techniques of Power Frequency Magnetic Fields originated from Electric Power Systems,” CIGRE Technical Brochure 373, Feb. 2009. Using the power line model it is possible to try various scenarios of arrangements and loadings that would be practically impossible to try on real lines. For example, it is concluded that the parallel running of two or more equally loaded double circuit lines does not practically affect the maximum values of the field intensities in comparison with one double circuit line alone. [11]CIGRE TF C4.205, “Characterisation of ELF Magnetic Fields,” CIGRE Technical Brochure 320, Apr. 2007. [12]K .M. Srinivasa, R. Maruti, Rajesh Kumar O. et al “Field measurements of electric and magnetic fields on HV and EHV transmission lines and substations,” IEEE Int. Symp. on Electrical Insulation: pp.347-350, Virginia, USA, 1998. [13]C.Garrido, A.F. Otero, J. Cidrás, “Low-frequency magnetic fields from electrical appliances and power lines,” IEEE Trans Power Delivery, vol.18, issue 4, pp. 1310-1319, Oct. 2003. 5. References [14]J. M. Bakhashwain, M. H. Shwehdi, U. M. Johar, A. A. AL-Naim, “Magnetic fields measurement and evaluation of EHV transmission lines in Saudi Arabia,” Proc. Int. Conf. on Non-Ionizing Radiation at UNITEN (ICNIRP 2003) Electromagnetic fields and our health, pp. 1-17, Oct. 2003. [1] International Commission on Non-Ionizing Radiation Protection, “Guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic fields (up to 300GHz),” Health Physics, vol. 74, issue 4, pp. 494 -522, Apr. 1998. [2] European Union Council, “Recommendation of 12 July 1999 on the limitation of exposure of the general public to electromagnetic fields (0Hz – 300GHz). (1999/519/EC),” pp. L 199/59 - L 199/70. Available: http://ec.europa.eu/health/electromagnetic_fields/docs/ emf_rec519_en.pdf [15]Abdel-Salam Hafiz Hamza, “Evaluation and measurement of magnetic field exposure over human body near EHV transmission lines,” Electric Power Systems Research vol.74, issue 1, pp. 105-118, Apr. 2005. [16]S. Ozen, “Evaluation and measurement of magnetic field exposure at a typical high-voltage substation and its power lines,” Radiation Protection Dosimetry vol.128, issue2, pp.198-205, doi:10.1093/rpd/ ncm326, Jan. 2008. [3] European Parliament and Council, “Directive 2004/40/EC of 29 April 2004 on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical Cigre Science & Engineering • N°5 June 2016 36 6. Biography [17] C.P. Nicolaou, A.P. Papadakis, P.A. Razis, G.A. Kyriacou, J.N. Sahalos, “Measurements and predictions of electric and magnetic fields from power lines,” Electric Power Systems Research vol. 81, issue 5, pp. 11071116, May 2011. E. I. Mimos was born in Athens, Greece, in 1978. He received the Electrical Engineering degree and the Ph.D. degree in electrical engineering from the University of Patras, Patras, Greece, in 2001, and 2009 respectively. He worked in Hellenic Electricity Distribution Network Operator (HEDNO) from 2010 to 2014. Since 2010 he has been working in the Technological Education Institute of Western Greece. [18]A.S. Farag, A. Al-Shehri, J. Bakhashwain, T.C. Cheng, D. Penn, “Impact of electromagnetic field management on the design of 500kV transmission lines,” Electric Power Systems Research vol.40, issue 3, pp. 203-238, Mar. 1997. [19]M. Shimizu, T. Nagae, N. Hayakawa, M. Hikita, H. Okubo, “Measurement of magnetic field distribution around power transmission line using reduced scale model,” 10th ISH 6, pp. 69 – 72, Montreal, 1997. [20]N.A. Rahman, H. Hussain, I. Said, T.S. Jalal, A.S. Farag, “Magnetic fields from a scaled down model transmission line – Simulation and comparison to measurements,” Proc. Asia-Pacific Conf. on Applied Electromagnetics, pp.147-151, DOI:10.1109/APACE.2005.1607795, Malaysia, Dec. 2005. His research interests include analysis and measurements of low frequency electric and magnetic fields produced by electric power systems. [21]J. Estacio, A. Escobar, G. Aponte, H. Cadavid, “A transmission line scale model for characterizing electric and magnetic fields,” In Electromagnetic Field, Health and Environment – Proc. of EHE’07, Studies in Applied Electromagnetics and Mechanics, IOS Press, 2008, pp. 162-167. D. K. Tsanakas received the Electrical Engineering degree and the Ph.D. degree in electrical engineering from the Technical University of Darmstadt, Darmstadt, Germany, in 1970 and 1976, respectively. [22]ENERTECH Consultants, “EMDEX II Specifications,” [Online]. Available: http://www.enertech.net/html/EMDEXIISpecs.html [23]IEC 61786, “Measurement of low-frequency magnetic and electric fields with regard to exposure of human beings –Special requirements for instruments and guidance for measurements,” Aug. 1998. He is Emeritus Professor of the Department of Electrical and Computer Engineering of University of Patras, Patras, Greece. From 1970 to 1973 and from 1977 to 1979, he was with the Public Power Corporation, Athens, Greece. From 1979 to 1990, he was a Professor of Electric Energy Systems, Demokritos University, Thrace, Greece and from 1990 to 2008 he was Professor and Director of the Power Systems Laboratory at the University of Patras, Patras, Greece. His research interests include short-circuit currents and their dynamic effects, analysis of electric and magnetic fields produced by power systems, and power system planning. [24] IEEE Standard 644-1994, “IEEE standard procedures for measurements of powerfrequency electric and magnetic fields from ac power lines,” Jan. 2002. [25]CIGRE WG 36.01, “Electric and Magnetic Fields Produced by Transmission Systems. Description of Phenomena - Practical Guide for Calculation,” CIGRE Tech. Brochure 21, 1980. [26] D. W. Deno and L. E. Zaffanela, “Field effects of overhead transmission lines and stations,” in Transmission Line Reference Book – 345 kV and Above, 2nd ed., California: Electric Power Research Institute, 1982, ch.8. [27]G. Filippopoulos and D. Tsanakas, “Analytical calculation of the magnetic field produced by electric power lines”, IEEE Transactions on Power Delivery, vol. 20, no. 2, pp. 1474-1482, April 2005. A. E. Tzinevrakis was born in Chania, Greece, in 1981. He received the Electrical Engineering degree and the Ph.D. degree in electrical engineering from the University of Patras, Patras, Greece, in 2004, and 2009 respectively. [28]Evangelos I. Mimos, Dimitrios K. Tsanakas and Antonios E. Tzinevrakis, “Optimum phase configurations for the minimization of the magnetic fields of underground cables”, Springer Berlin, Electrical Engineering, vol. 91, pp. 327–335, Jan. 2010. [29]A. E. Tzinevrakis, D. K. Tsanakas and E. I. Mimos, “Analytical calculation of the electric field produced by single-circuit power lines,” IEEE Transactions on Power Delivery, vol. 23, no. 3, pp. 1495-1505, July 2008. His research interests include analysis and calculations of low frequency electric and magnetic fields produced by electric power systems. [30]A. E. Tzinevrakis, D. K. Tsanakas and E. I. Mimos, “Electric field analytical formulas for single-circuit power lines with a horizontal arrangement of conductors,” IET Generation, Transmission & Distribution, vol. 3, no. 6, pp. 509-520, 2009. Cigre Science & Engineering • N°5 June 2016 37