Study On The Simulation And Identification Of Transient Current Travelling Waves Caused By Direct Lightning Strokes

Research on the identification of direct lightning strokes is the basis of analyzingthe reason of the lightning accident and identification the responsibility of the lightningaccident, which can provide effective technical means for realizing differentiationstrategy of lightning design and reform. Based on the analyzing the current research foridentification of direct lightning strokes the thesis studies on recognition method andmeasurement of the direct lightning strokes. The main work involving is as follows:Firstly, in this paper, the simulation models of transmission lines which installedthe monitoring equipments were established based on ATP-EMTP software.Considering the shielding effect of the ground wires for lightning, different range ofamplitudes of lightning current were applied to simulate the current on conductors.Then the characteristic of waveform caused by different direct lightning strokes wereanalyzed according to the generation mechanism process.Secondly, based on the characteristic of number of phase which lightning current isinjected, the different direct lightning strokes were classified into three groupspreliminarily by comparing the energy of the three phase conductors based on thecoupling coefficient of parallel conductor. Ultimately achieve the goal of identifying ofdirect lightning by identifying the type of the lightning stroke in each group byanalyzing the characters of current in time and frequency domain. On above of all,program of identification of the direct lightning strokes was written with C#basedon.NET. And the type of the field data was analyzed preliminarily.Finally, in order to carry out more in-depth analysis on the identification of directlightning strokes, power frequency current of conductors were also need to be measuredas well as the transient current travelling waves. Then the basic principles of the currentmeasurement based on AMR sensor were introduced. The current measurement devicebased on AMR sensor was designed and developed. Meanwhile, in order to solve theproblem that then sensor’s measurement sensitivity decreases when exposing to thelarge magnetic disturbing fields, Set/Reset circuit was designed and tested.Performances of the device were tested in the laboratory. Measurement of powerfrequency current and lightning current were tested. The tests show the device canachieve the contactless measurement of the power frequency current and lightning current at the same time, and has the advantages of good security and small size.