Dissertation > Astronomy,Earth Sciences > Atmospheric science (meteorology ) > Meteorological elements,atmospheric phenomenon > Atmospheric phenomena > Atmospheric electricity phenomena ( atmospheric electricity ) > Unstable weather of the electric

Algorithm Research of the Lightning Horizontal Electric Field Over Smooth and Lossy Ground

Author FanYanFeng
Tutor ZhangQiLin
School Nanjing University of Information Engineering
Course Of lightning scientific and technical
Keywords lightning horizontal electric field C-R formula Sommerfeld integral
CLC P427.32
Type Master's thesis
Year 2013
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Lightning is a kind of strong discharge phenomenon in nature which can radiate intensive electromagnetism pulse. The electromagnetism fields may couple into the overhead transmission lines or power installations lying underground and cause huge damage to the power systems. The lightning horizontal electric field is a key parameter during the research of the lightning induced over-voltage, considering the inherent difficuley in measuring lightning horizontal electric field, it is necessary to take accurate and efficient algorithm to obtain the results.The paper summarizes the most common used formulas for calculating the horizontal electric field in details, such as the C-R formula both in frequency domain and time domain and the accurate algorithm proposed by Sommerfeld. The paper gives the derivation processes of all the methods, and generalizes C-R formula in frequency domain for the case of vertical stratified ground. At the same time, waveforms of the horizontal electric fields of the different methods with different parameters are simulated by Matlab software, based on the MTLL return stroke model and double-Herdler function base current, then we compares these waveforms with the results obtained from finite-different time-domain method(FDTD) and draws some conclusions:(1) The C-R formulas both in time and frequency domain should take the attenuation function into consideration for better accuracy;(2) The parameters in C-R formula should meet certain conditions, otherwise the caculation results will have substantial errors;(3) In the case of the stratified ground, the accuracy of the C-R formula is different with the different distribution of the ground conductivity;(4) No mattte what parameters are choosen, approximate algorithms are more accurate under the first return stroke base current than the subsequent return stroke base current;(5) The caculating results obtains from both Sommerfeld algorithm and FDTD can be the reference standard which used to examine the results obtained from the approximate algorithms.

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