Influence of Ground Electrical Properties on Lightning-Electromagnetic Fields for Wind Farms and Overhead Lines - Applications of the FDTD Method

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School of Electrical Engineering | Doctoral thesis (article-based) | Defence date: 2016-11-16
Degree programme
127 + app. 69
Aalto University publication series DOCTORAL DISSERTATIONS, 203/2016
Direct and indirect lightning events result in transient disturbances in electric power systems that may cause damages of the components of the power system and interruptions of the power supply. The resistivity and permittivity of the ground have a significant influence on these transient disturbances due to both lightning events. In order to study this influence, five research tasks have been implemented using the finite-difference time-domain method. The 1st and 2nd tasks are relevant to indirect lightning problems where lightning-induced voltages (LIVs) on overhead lines have been investigated due to nearby return strokes on the ground. The 3rd and 4th tasks are related to direct lightning problems where the electromagnetic fields have been studied due to direct stroke to a grounding system and a grounded wind turbine (WT) considering the impact of the horizontal stratification of the ground. The 5th one includes both direct and indirect lightning problems where the electromagnetic fields are studied for a grounded WT struck by a return stroke beside a nearby overhead line. For a proper design of the overhead line insulation, it is required to accurately compute LIVs. The influences of the ground resistivity, permittivity and the rate of rise of lightning current are investigated on the lightning electromagnetic fields and LIVs impinging overhead lines. A formula has been proposed to calculate the peak values of LIVs due to the typical first and subsequent strokes in the IEEE Standard 1410-2010 considering high values of ground resistivity. The proposed formula is applied to calculate the indirect lightning performance in terms of an annual number of flashovers per 100 km of the overhead line. The grounding system is essential for effective lightning protection against direct strokes so the effect of ground resistivity and permittivity on the impedance of grounding systems has been studied. Such study is extended to investigate the lightning-electromagnetic fields on the cable sheath in a wind farm due to a lightning stroke striking a grounded WT. The impact of connecting the grounding systems of the WTs on mitigating these electromagnetic fields has been also investigated. For the horizontally stratified ground case, it is found that the reflections at the boundary between the two layers affect these electromagnetic fields significantly. Since overhead lines may exist nearby WTs, the influence of ground resistivity and permittivity on LIVs and electric fields impinging the line is studied due to a return stroke striking a nearby grounded WT. The first and subsequent strokes are adopted for this study besides the consideration of the horizontally stratified ground case.
Supervising professor
Lehtonen, Matti, Prof., Aalto University, Department of Electrical Engineering and Automation, Finland
Thesis advisor
Abdel-Rahman, Mansour Hassan, Prof., Mansoura University, Egypt
Badran, Ebrahim A., Associate Prof., Mansoura University, Egypt
FDTD method, return stroke, ground resistivity and permittivity, overhead line, grounding system, wind turbine, lightning-induced voltage
Other note
  • [Publication 1]: M. E. M. Rizk, F. Mahmood, M. Lehtonen, E. Badran and M. Abdel-Rahman, "Influence of Highly Resistive Ground Parameters on Lightning Induced Overvoltages Using 3-D FDTD Method", IEEE Transactions on Electromagnetic Compatibility, vol. 58, no. 3, pp. 792-800, 2016.
    DOI: 10.1109/TEMC.2016.2527503 View at publisher
  • [Publication 2]: M. E. M. Rizk, F. Mahmood, M. Lehtonen, E. Badran and M. Abdel-Rahman, "Computation of Peak Lightning-Induced Voltages due to the Typical First and Subsequent Strokes Considering High Ground Resistivity", Accepted for publication in IEEE Transactions on Power Delivery, 2016.
    DOI: 10.1109/TPWRD.2016.2555856 View at publisher
  • [Publication 3]: M. E. M. Rizk, E. A. Badran and M. H. Abdel-Rahman, "FDTD Calculation of Transient Electromagnetic Fields in the Grounding System of Wind Towers due to Direct Lightning Strikes", Journal of Lightning Research, vol. 6, no. 1, pp. 1-13, Dec. 2014.
    DOI: 10.2174/1652803401306010001 View at publisher
  • [Publication 4]: M. E. M. Rizk, F. Mahmood, M. Lehtonen, E. Badran and M. Abdel-Rahman, "Investigation of Lightning Electromagnetic Fields on Underground Cables in Wind Farms", IEEE Transactions on Electromagnetic Compatibility, vol. 58, no. 1, pp. 143-152, 2016.
    DOI: 10.1109/TEMC.2015.2493206 View at publisher
  • [Publication 5]: M. E. M. Rizk, F. Mahmood, M. Lehtonen, E. Badran and M. Abdel-Rahman, "Induced Voltages on Overhead Line by Return Strokes to Grounded Wind Tower considering Horizontally Stratified Ground", Accepted for publication in IEEE Transactions on Electromagnetic Compatibility, 2016.
    DOI: 10.1109/TEMC.2016.2588000 View at publisher