Abstract—This paper reports the main author’s scientific

results concerning lightning-induced voltage appraisal and provides some indications on future research on this topic. The results here reported have been achieved thanks to the activity carried out by the research group that the author is coordinating at the University of Bologna. Such an activity has taken large advantage from long lasting collaborations with some of the most distinguished colleagues and research groups that are active worldwide in the lightning/power area.

Index Terms — EM coupling, EMTP, Induced voltages, LEMP, Lightning, LIOV code, Insulation coordination, Return Stroke Current Models

I. INTRODUCTION HIS paper has been motivated by the two questions raised by the initiator of the World Meeting on Lightning prof.

Horacio Torres, namely: 1) What has been, in your opinion, your most Important contribution to lightning research? and 2) in your opinion, what lightning research issues should be given special attention in the coming years? The activity carried out by the author on lightning-induced voltages started in 1984 when Prof. Dino Zanobetti, director at that time of the Institute of Industrial Electrical Engineering of the University of Bologna, initiated a research cooperation with the Power Systems Laboratory of the Swiss Federal Institute of Technology, Lausanne (EPFL), directed by Prof. Jean-Jacques Morf, on the analysis of the effect of the nuclear electromagnetic pulse (NEMP) on power and telecommunication lines. The research group at EPFL dealing with Electro Magnetic Compatibility (EMC) issues, coordinated at that time by Prof. Michel Ianoz, was then involved into the joint research project, which was having the financial support of the Italian National Research Council and of the Swiss National Science Foundation. Some of the first results of such a cooperation are reported in [1]. Similarities in the waveshape of lightning electro magnetic pulse (LEMP) and NEMP then motivated the extension of the research activity to the analysis of the interaction between LEMP and overhead power lines: this was accomplished thanks to the involvement and the cooperation of Prof. Carlo Mazzetti, of the Department of Electrical Engineering of the University of

C. A. Nucci is with the Department of Electrical, Electronic and

Information Engineering at the School of Engineering and Architecture of the University of Bologna (e-mail: carloalberto.nucci@unibo.it).

Rome ‘La Sapienza’, and of Professor Farhad Rachidi, at that time working at his PhD dissertation under the supervision of Michel Ianoz. The first journal paper of such an established Italian-Swiss research team was dealing with the frequency analysis of LEMP [2]. In the following years, other major research cooperation with some of the most distinguished colleagues and research groups active worldwide in the lightning/power area have been carried out, as it appears going through the reference list and the acknowledgements. In reply to the two above mentioned questions, the results obtained by the author concern i) lightning return stroke current modeling for the calculation

of the lightning electromagnetic pulse (LEMP), ii) analysis of the LEMP coupling to overhead lines, iii) the development of models and relevant computer codes

for the appraisal of lightning induced voltage calculations and for the estimation of the so called lightning performance of distribution lines/systems.

They will be schematically summarized in Section II, III and IV a respectively. Some of them will be discussed during the oral presentation at Womel. Section V is devoted to the conclusive remarks, which include the discussion on the research issues that should be given special attention in the near future within the topic we are dealing with.

II. LIGHTNING RETURN STROKE CURRENT MODELS AND LEMP CALCULATION

A. Lightning Return Stroke Model with Specified Channel-Base Current

- Development of the MTLE return stroke current model in cooperation with EPFL and University of Rome ‘La Sapienza’ [3,4]

- Extension of the MTLE model to take into account the presence of elevated strike objects [5,6]

- Comparative analysis of return stroke models with specified channel-base current [7,8].

B. LEMP measurement and calculation - Simultaneous measurement at the NASA Kennedy Space

Center of lightning return stroke current, and electric and magnetic fields at very close range (down to 30 m) [9]

- Full wave computation of LEMP and validity assessment of simplified approaches [10]

Computation of Lightning-Induced Voltages on Overhead Lines Carlo Alberto Nucci, Fellow, IEEE

T

III. ANALYSIS OF THE LEMP COUPLING TO OVERHEAD LINES

A. Critical comparison of existing coupling models - A comprehensive study was performed in order to assess

the adequacy of the models used to compute lightning-induced overvoltages based on the so called Transmission Line approximation, and it was shown, that in a model that has been extensively used in the power literature a source term is omitted [11,12,13]

- The analysis of the equivalence of some of the available coupling models has been carried out in [14]. This has dispelled the apparent confusion that was existing before on the topic and has replied, in particular, to the question “What is the electromagnetic field component that mostly affect the coupling between LEMP and overhead lines”.

B. Analysis of the effect of line losses and corona in LEMP-to-line coupling mechanism

- Analysis of the effect of the ground resistivity on the amplitude of the induced voltages: it has been demonstrated that for some observation points along the line the induced voltage amplitude on the line can be enhanced, a theoretical results that finds confirmation in experimental ones, and explains them [15,16]

- Analysis of the effect of corona on the amplitude of the induced voltages [17,18]. This was a pioneering work: although many studies have been carried out on the topic concerning direct strokes to overhead lines, practically no work was carried out before [17] on induced voltages. The results are quite surprising: the induced overvoltage amplitude is shown to be enhanced by corona, a result that has been afterwards confirmed by other researchers.

- Analysis of the influence of the taking into account the frequency dependence of soil parameters when calculating lightning induced voltages [19].

C. Analysis of the effect of leader field on the induced voltages

- It has been shown that for lightning strokes close to the line terminations the dart leader-induced voltages can be large enough to trigger protection devices before the return stroke phase [20].

D. Analysis of LEMP-to-multiconductor lines interaction. - The line response has been thoroughly analyzed by making

use of advanced models [21,22,23] - New expressions for the soil impedance have been

proposed and compared with the existing ones [24,25].

IV. MODELS AND RELEVANT COMPUTER CODES FOR THE APPRAISAL OF LIGHTNING-INDUCED VOLTAGE CALCULATIONS

A. LIOV and LIOV-EMTP Codes - LIOV code. Together with Prof. Farhad Rachidi of the

EPFL, an innovative procedure for the calculation of lightning-induced voltages and its implementation into a computer code – LIOV (Lightning Induced Over-Voltage) code – has been proposed. LIOV is a de-facto standard in the power community and is based on the theory and the

results summarized so far. Such a code has been then interfaced with the Electro Magnetic Transient program, EMTP (see next bullet), becoming the most advanced simulation tool for the calculation of lightning-induced voltages on distribution systems. This work has been carried out within an international framework, involving the Swiss EPFL, the University of Rome and the Italian CESI. The LIOV code has been enriched in the years thanks to the contribution of several colleagues, Prof. Alberto Borghetti, Dr. Silvia Guerrieri, Prof. Mario Paolone, Dr. Fabio Napolitano and more recently by Eng. Fabio Tossani [11,15,17,20,21,23,26,27,28]. A free version of the LIOV Code for a single-conductor and lossless line can be downloaded from the following web address: http://www.liov.ing.unibo.it/.

- LIOV-EMTP code. In order to take into account the

presence of complex types of terminations, i.e. surge arresters, groundings of shielding wires, transformers or other power components, as well as of complex network topologies, the LIOV code has been interfaced with electromagnetic transient programs, namely EMTP [29], Matlab-Simulink [30] and EMTP-RV [31]. At each time step of the time domain transient calculation accomplished by applying a FDTD second order scheme, LIOV performs: 1) the LEMP calculation, 2) the field-to-line coupling solution and 3) the update of the variables to be exchanged with EMTP for the solution of the boundary conditions at the line terminations, as schematically shown in Fig. 1.

Fig. 1 – Interface between LIOV and LIOV-EMTP-RV [31]

- LIOV and LIOV-EMTP codes validation with

experimental results by means of reduced scale models [32], NEMP simulators [30] and data from artificially triggered lightning [36-38].

B. Assessment of the lightning performance of distribution systems - Inference of statistical distributions of lightning current

parameters ‘decontaminated’ from the presence of the relevant instrumented tower, of importance when calculating lightning voltages due to nearby strikes [39].

- Development of a statistical procedure for achieving the assessment of the so-called lightning performance of distribution systems based on the most advanced models available, which combines the Monte Carlo method and the LIOV code [40,41]

- Development of models of real distribution systems, including power distribution transformers [42], compact

lines and with resonant grounding [43,44] C. Correlation between voltage sags and lightning events - Development of an advanced procedure that takes into

account the statistical distribution of the location uncertainty provided by modern lightning locations systems and makes use of voltage sag field data in order to correlate them, and relevant experimental validation on a large portion of a distribution network in north Italy [45-48]

V. CONCLUSIVE REMARKS AND POSSIBLE FUTURE RESEARCH ACTIVITY In the last decades the research activity on the topic has allowed to improve significantly the appraisal of lighting induced overvoltages, thanks to the development of accurate models and to the constantly increasing computer performance. As a matter of fact, the IEEE 1410 Standard, which was recommending the use of the analytical equation proposed by Sune Rusck only ten years ago – which by the way is certainly correct within the considered assumptions – is now recommending the use of more advanced models, such as those referred to in this paper. There are however several margins for improvement. In this respect a few hints and proposed hereunder.

A. Overvoltage calculations using advanced Numerical Electromagnetic Analysis – NEA

NEA methods [e.g. A. Ametani, T. Hoshino, M. Ishii, T. Noda, S. Okabe and K. Tanabe: Numerical electromagnetic analysis method and its application to surge phenomena, CIGRE 2008 General Meeting, Paper C4-108, 2008] solve Maxwell’s equation directly with no assumption of a wave propagation mode, and they represent therefore a powerful approach for the lightning surge analysis when the geometry of the problem does not allow the application of the transmission line approximation [49]. There are several problems concerning the protection of lighting-induced surges that could take advantage form this technique. In some cases, part of the calculation can be performed using the TL approximation and part using NEA methods.

B. Influence of the presence of buildings around the lines Some studies have already tackled the problem of analysing the effect of sthe presence of buildings near the overhead lines [50], which in some case can may results in attenuation of the amplitude of the induced surges. The research activity aimed at assessing more and more realistic distribution system configurations has to take into account also the realistic representation of the environment surrounding the distributions lines.

C. Lightning and renewable energy systems Some studies have already tackled the problem of the effects of lightning strokes on wind turbines (for instance in [51] the effect of the lighting current on the turbine bearings has been analysed, modelled, and tested versus experimental results),

but as the diffusion of wind generators is expected to increase, lightning impact on this type of apparatuses needs to be further studied.

ACKNOWLEDGMENT The material presented in this paper reports some of the

results of a joint Italian-Swiss research cooperation carried out during the last three decades involving Alberto Borghetti, Silvia Guerreri, Michel Ianoz, Carlo Mazzetti, Fabio Napolitano, Mario Paolone, Farhad Rachidi, Marcos Rubinstein and, more recently, Fabio Tossani. Their contribution is gratefully acknowledged. The author wish to express his gratitude also to Aki Ametani, Marina Bernardi, Vernon Cooray, Maria Teresa Correia de Barros, Jinliang He, Manuel Martinez, Alexander Piantini, Vladimir A. Rakov, Fred M. Tesche and Martin A. Uman for their valuable cooperation throughout these years. The lightning research activities in Italy here illustrated have been financially supported by the Italian National Research Council, by ENEL-CESI, RSE, and the European COST Action P18 ‘The Physics of Lightning Flash and Its Effects’.

REFERENCES

[1] M. Ianoz, C. A. Nucci, and F. M. Tesche, “Transmission line theory for

field-to-transmission line coupling calculations,” Electromagnetics, vol. 8, no. 2–4, pp. 171–211, 1988.

[2] C. A. Nucci, C. Mazzetti, F. Rachidi, and M. Ianoz, “Analyse du champ électromagnétique dû à une décharge de foudre dans les domaines temporel et fréquentiel,” Ann. Des Télécommunications, vol. 43, no. 11–12, pp. 625–637, 1988.

[3] C. A. Nucci, C. Mazzetti, F. Rachidi, and M. Ianoz, “On lightning return stroke models for LEMP calculations,” 19th Int. Conf. Light. Prot. Graz, Austria, pp. 464–470, 1988.

[4] F. Rachidi and C. A. Nucci, “On the Master, Uman, Lin, Standler and the Modified Transmission Line Lightning return stroke current models,” J. Geophys. Res., vol. 95, no. D12, p. 20389, 1990.

[5] S. Guerrieri, C. A. Nucci, F. Rachidi, and M. Rubinstein, “On the influence of elevated strike objects on directly measured and indirectly estimated lightning currents,” IEEE Trans. Power Deliv., vol. 13, no. 4, pp. 1543–1551, 1998.

[6] F. Rachidi, V. A. Rakov, C. A. Nucci, and J. L. Bermudez, “Effect of vertically extended strike object on the distribution of current along the lightning channel,” J. Geophys. Res., vol. 107, no. D23, pp. 1–6, 2002.

[7] C. A. Nucci, G. Diendorfer, M. A. Uman, F. Rachidi, M. Ianoz, and C. Mazzetti, “Lightning return stroke current models with specified channel-base current: A review and comparison,” J. Geophys. Res., vol. 95, no. D12, pp. 20395–20408, 1990.

[8] C. A. Nucci, “Lightning-induced voltages on overhead power lines. Part I: Return-stroke current models with specified channel-base current for the evaluation of the return-stroke electromagnetic fields,” Electra, vol. 161, pp. 74–102, 1995.

[9] M. Rubenstein, F. Rachidi, M. A. Uman, R. Thottappillil, V. A. Rakov, and C. A. Nucci, “Characterization of vertical electric fields 500 m and 30 m from triggered lightning,” J. Geophys. Res., vol. 100, no. D5, pp. 8863–8872, 1995.

[10] F. Delfino, R. Procopio, M. Rossi, F. Rachidi, and C. A. Nucci, “Lightning return stroke current radiation in presence of a conducting ground: 2. Validity assessment of simplified approaches,” J. Geophys. Res., vol. 113, no. D05111, pp. 1–11, 2008.

[11] C. A. Nucci, F. Rachidi, M. Ianoz, and C. Mazzetti, “Lightning-induced voltages on overhead power lines,” IEEE Trans. Electromagn. Compat., vol. 35, no. 1, pp. 75–86, 1993.

[12] F. Rachidi, C. A. Nucci, M. Ianoz, and C. Mazzetti, “Comparison of Two Coupling Models for Lightning-Induced Overvoltage Calculations,” IEEE Trans. Power Deliv., vol. 10, no. 1, pp. 330–339, 1995.

[13] C. A. Nucci, “Lightning-induced voltages on overhead power lines. Part II: Coupling models for the evaluation of the induced voltages,” Electra, vol. 162, pp. 121–145, 1995.

[14] C. A. Nucci and F. Rachidi, “On the contribution of the electromagnetic field components in field-to-transmission lines interaction,” IEEE Trans. Electromagn. Compat., vol. 37, no. 4, pp. 505–508, 1995.

[15] F. Rachidi, C. A. Nucci, M. Ianoz, and C. Mazzetti, “Influence of a lossy ground on lightning induced voltages on ovehead lines,” IEEE Trans. Electromagn. Compat., vol. 38, no. 3, pp. 250–264, 1996.

[16] S. Guerrieri, C. A. Nucci, and F. Rachidi, “Influence of the ground resistivity on the polarity and intensity of lightning induced voltages,” Proc. 10th Int. Symp. High Volt. Eng. Montr. August 24-30, 1997.

[17] C. A. Nucci, S. Guerrieri, M. T. Correia De Barros, and F. Rachidi, “Influence of corona on the voltages induced by nearby lightning on overhead distribution lines,” IEEE Trans. Power Deliv., vol. 15, no. 4, pp. 1265–1273, 2000.

[18] G. Dragan, G. Florea, C. A. Nucci, and M. Paolone, “On the influence of corona on lightning-induced overvoltages,” in 30th International Conference on Lightning Protection, Cagliari, Italy, 2010.

[19] M. Akbari, K. Sheshyekani, A. Pirayesh, F. Rachidi, M. Paolone, A. Borghetti, and C. A. Nucci, “Evaluation of lightning electromagnetic fields and their induced voltages on overhead lines considering the frequency dependence of soil electrical parameters,” IEEE Trans. Electromagn. Compat., vol. 55, no. 6, pp. 1210–1219, 2013.

[20] F. Rachidi, M. Rubinstein, S. Guerrieri, and C. A. Nucci, “Voltages induced on overhead lines by dart leaders and subsequent return strokes in natural and rocket-triggered lightning,” IEEE Trans. Electromagn. Compat., vol. 39, no. 2, pp. 160–166, 1997.

[21] F. Rachidi, C. A. Nucci, M. Ianoz, and C. Mazzetti, “Response of multiconductor power lines to nearby lightning return stroke electromagnetic fields,” IEEE Trans. Power Deliv., vol. 12, no. 3, pp. 1404–1411, 1997.

[22] F. Rachidi, C. A. Nucci, and M. Ianoz, “Transient analysis of multiconductor lines above a lossy ground,” IEEE Trans. Power Deliv., vol. 14, no. 1, pp. 294–302, 1999.

[23] F. Napolitano, F. Tossani, C. A. Nucci, and F. Rachidi, “On the transmission-line approach for the evaluation of LEMP coupling to multiconductor lines,” IEEE Trans. Power Deliv., vol. 30, no. 2, pp. 861–869, 2015.

[24] F. Rachidi, S. L. Loyka, C. A. Nucci, and M. Ianoz, “A new expression for the ground transient resistance matrix elements of multiconductor overhead transmission lines,” Electr. Power Syst. Res., vol. 65, no. 1, pp. 41–46, 2003.

[25] F. Tossani, F. Napolitano, F. Rachidi, and C. A. Nucci, “An improved approach for the calculation of the transient ground resistance matrix of multiconductor lines,” IEEE Trans. Power Deliv., vol. PP, pp. 1–1, 2015.

[26] A. Borghetti, C. A. Nucci, M. Paolone, and F. Rachidi, “Characterization of the response of an overhead line to lightning electromagnetic fields,” in Proc. of 25th International Conference on Lightning Protection, Rhodos, September 18-22, 2000.

[27] A. Borghetti, C. A. Nucci, M. Paolone, and M. Bernardi, “Effect of the lateral distance expression and of the presence of shielding wires on the evaluation of the number of lightning induced voltages,” in Proc. 25th International Conference on Lightning Protection, Rhodos, September 18-22, 2000.

[28] M. Paolone, C. A. Nucci, and F. Rachidi, “A new finite difference time domain scheme for the evaluation of lightning induced overvoltages on multiconductor overhead lines,” in Proc. of 5th international Conference on Power System Transients, Rio de Janeiro, Brazil, 2001.

[29] C. A. Nucci, V. Bardazzi, R. Iorio, A. Mansoldo, and A. Porrino, “A code for the calculation of lightning-induced overvoltages and its interface with the electromagnetic transient Program,” in Proc. of 22nd International Conference on Lightning Protection, Budapest, Hungary, 1994.

[30] A. Borghetti, J. A. Gutierrez, C. A. Nucci, M. Paolone, E. Petrache, and F. Rachidi, “Lightning-induced voltages on complex distribution systems: models, advanced software tools and experimental validation,” J. Electrostat., vol. 60, no. 2–4, pp. 163–174, 2004.

[31] F. Napolitano, A. Borghetti, C. A. Nucci, M. Paolone, F. Rachidi, and J. Mahseredjian, “An advanced interface between the LIOV code and the EMTP-RV,” in Proc. of 29th International Conference on Lightning Protection, Uppsala, Sweden, 2008.

[32] A. Piantini, J. M. Janiszewski, A. Borghetti, C. A. Nucci, and M. Paolone, “A scale model for the study of the LEMP response of complex power distribution networks,” IEEE Trans. Power Deliv., vol. 22, no. 1, pp. 710–720, 2007.

[33] M. Paolone, C. A. Nucci, E. Petrache, and F. Rachidi, “Mitigation of lightning-induced overvoltages in medium voltage distribution lines by means of periodical grounding of shielding wires and of surge arresters: modeling and experimental validation,” IEEE Trans. Power Deliv., vol. 19, no. 1, pp. 423–431, 2004.

[34] E. Petrache, F. Rachidi, M. Paolone, C. A. Nucci, V. A. Rakov, and M. A. Uman, “Lightning induced disturbance in buried cables - Part I: Theory,” IEEE Trans. Electromagn. Compat., vol. 47, no. 3, pp. 498–508, 2005.

[35] M. Paolone, E. Petrache, F. Rachidi, C. A. Nucci, V. A. Rakov, M. A. Uman, D. Jordan, K. Rambo, J. Jerauld, M. Nyffeler, and J. Schoene, “Lightning induced disturbances in buried cables - Part II: Experiment and model validation,” IEEE Trans. Electromagn. Compat., vol. 47, no. 3, pp. 509–520, 2005.

[36] E. Petrache, M. Paolone, F. Rachidi, C. A. Nucci, V. Rakov, M. Uman, D. Jordan, K. Rambo, J. Jerauld, M. Nyffeler, and J. Schoene, “Lightning-induced currents in buried coaxial cables: A frequency-domain approach and its validation using rocket-triggered lightning,” J. Electrostat., vol. 65, no. 5–6, pp. 322–328, 2007.

[37] J. Schoene, M. A. Uman, V. a. Rakov, J. Jerauld, K. J. Rambo, D. M. Jordan, G. H. Schnetzer, M. Paolone, C. A. Nucci, E. Petrache, and F. Rachidi, “Lightning currents flowing in the soil and entering a test power distribution line via its grounding,” IEEE Trans. Power Deliv., vol. 24, no. 3, pp. 1095–1103, 2009.

[38] M. Paolone, F. Rachidi, A. Borghetti, C. A. Nucci, M. Rubinstein, V. A. Rakov, and M. A. Uman, “Lightning electromagnetic field coupling to overhead lines: theory, numerical simulations, and experimental validation,” IEEE Trans. Electromagn. Compat., vol. 51, no. 3, pp. 532–547, 2009.

[39] A. Borghetti, C. A. Nucci, and M. Paolone, “Estimation of the Statistical Distributions of Lightning Current Parameters at Ground Level From the Data Recorded by Instrumented Towers,” IEEE Trans. Power Deliv., vol. 19, no. 3, pp. 1400–1409, 2004.

[40] A. Borghetti, C. A. Nucci, and M. Paolone, “An improved procedure for the assessment of overhead line indirect lightning performance and its comparison with the IEEE Std. 1410 method,” IEEE Trans. Power Deliv., vol. 22, no. 1, pp. 684–692, 2007.

[41] A. Borghetti, C. A. Nucci, and M. Paolone, “Indirect-lightning performance of overhead distribution networks with complex topology,” IEEE Trans. Power Deliv., vol. 24, no. 4, pp. 2206–2213, 2009.

[42] A. Borghetti, A. S. Morched, F. Napolitano, C. A. Nucci, and M. Paolone, “Lightning-induced overvoltages transferred through distribution power transformers,” IEEE Trans. Power Deliv., vol. 24, no. 1, pp. 360–372, 2009.

[43] F. Napolitano, A. Borghetti, C. A. Nucci, M. L. B. Martinez, G. P. Lopes, and G. J. G. Dos Santos, “Protection against lightning overvoltages in resonant grounded power distribution networks,” Electr. Power Syst. Res., vol. 113, pp. 121–128, 2014.

[44] F. Napolitano, F. Tossani, A. Borghetti, C. A. Nucci, M. L. B. Martinez, G. P. Lopes, G. J. G. Dos Santos, and D. R. Fagundes, “Lightning performance of a real distribution network with focus on transformer protection,” Electr. Power Syst. Res., 2016.

[45] M. Paolone, L. Peretto, R. Sasdelli, R. Tinarelli, M. Bernardi, and C. A. Nucci, “On the use of data from distributed measurement systems for correlating voltage transients to lightning,” IEEE Trans. Instrum. Meas., vol. 53, no. 4, pp. 1202–1208, 2004.

[46] A. Borghetti, F. Napolitano, C. A. Nucci, M. Paolone, M. Bernardi, F. Rachidi, and K. Yamabuki, “Correlation of lightning events and faults in distribution power networks: a joint research project,” in Proceedings of the Cigre General Session 2008, Paris, France, 2008.

[47] M. Bernardi, A. Borghetti, F. Napolitano, C. A. Nucci, M. Paolone, and W. Schulz, “Voltage Transients in a Distribution Network Correlated with Events Identified by a Lightning Location System,” in International Symposium on Lightning Protection, Curitiba, Brazil, Nov 9-13, 2009, pp. 533–538.

[48] D. Pavanello, F. Rachidi, W. Janischewskyj, M. Rubinstein, V. O. Shostak, C. A. Nucci, K. L. Cummins, A. M. Hussein, and J. S. Chang, “On the current peak estimates provided by lightning detection networks for lightning return strokes to tall towers,” IEEE Trans. Electromagn. Compat., vol. 51, no. 3, pp. 453–458, 2009.

[49] F. Napolitano, A. Borghetti, C. A. Nucci, F. Rachidi, and M. Paolone, “Use of the full-wave Finite Element Method for the numerical electromagnetic analysis of LEMP and its coupling to overhead lines,” Electr. Power Syst. Res., vol. 94, pp. 24–29, 2013.

[50] A. Borghetti, F. Napolitano, C. A. Nucci, and M. Paolone, “Effects of nearby buildings on lightning induced voltages on overhead power distribution lines,” Electr. Power Syst. Res., vol. 94, pp. 38–45, 2013.

[51] F. Napolitano, M. Paolone, A. Borghetti, C. A. Nucci, A. Cristofolini, C. Mazzetti, F. Fiamingo, and M. Marzinotto, “Models of wind-turbine main-shaft bearings for the development of specific lightning protection systems,” IEEE Trans. Electromagn. Compat., vol. 53, no. 1, pp. 99–107, 2011.

Carlo Alberto Nucci is full professor and head of the Power Systems Laboratory of the Department of Electrical, Electronic and Information Engineering ‘Guglielmo Marconi’ of the University of Bologna. He is author or co-author of over 300 scientific papers published on peer-reviewed journals or on proceedings of international conferences, of five book chapters edited by IEE (two), Kluwer, Rumanian Academy of Science and WIT press and of a couple of IEEE Standards and some CIGRE technical brochures. He is a

Fellow of the IEEE and of the IET, CIGRE honorary member and has received some best paper/technical international awards, including the CIGRE Technical Committee Award and the ICLP Golde Award. From January 2006 to September 2012 he has served as Chairman of Cigré Study Committee C4 ‘System Technical Performance’. Since January 2010 he is serving as Editor in Chief of the Electric Power Systems Research journal, Elsevier. Prof. Nucci is doctor honoris causa of the University Politehnica of Bucharest and corresponding member of the Bologna Science Academy. He has served as president of the Italian Group of University Professors of Electrical Power Systems (GUSEE) from 2012 to 2015. He is an advisor of the Global Resource Management Program of Doshisha University, Kyoto, supported by the Japanese Ministry of Education and Science. He is the coordinator of the Working Group ‘Smart City’ of the University of Bologna, has been serving as member of the EU Smart City Stakeholder Platform since 2013, and since 2014 is representing PES in the IEEE Smart City Initiatives Program.