3D Simulation Of The Lightning Leader And Its Application

To study the propagation characteristics of the lightning leader and the interactionbetween the lightning leader and the wind turbines，a2-dimension random model of lightningleader is used here to simulate and analyze the cases of lightning flash striking the windturbine， then we proposed a3D self-consistent propagation model of lightning leader andcarried out further research based on it.Random simulation results demonstrate that as the horizontal distance between the initialdownward leader and the turbine increases, the probability of the turbine to be stroke bylightning decreases instead, and even declines to about4%when the distance is around500meters. The lightning strike points mostly are the turbine blades and there is some distinctionin the striking character when the turbine is under different condition. When the inclinationangle of the No.1turbine blade is15o～45o, the turbine will bear a little higher risk to bestroke by lightning if the horizontal distance between the downward initial leader and theturbine is not longer than300meters. But the probability of the turbine to be stroke isrelatively much higher if the distance becomes about500meters, obviously higher than that ofturbines under any other condition. All these integral analysis above can come to a conclusionthat when the inclination angle of the No.1turbine blade is15o~45o,the probability of theturbine to be stroke is relatively larger.Considering the limitation of the random model，a3D simulation of the lightning leaderconsistent propagation model is mainly carried out to analyze the characteristic of theinitiation and propagation process under the influence the downward stepped leader.Meanwhile the velocity、charge density per unit and the length every step moved can becalculated based on the transient electric field. Combined with the optical and electrical dataof the natural and artificially triggered lightning，the simulation results of the self-consistentpropagation model showed that the initiation of the positive upward leader mainly depends onthe electric field intensity and the geometry of the structure in the simulated domain. As theleader initiated and propagated，its velocity increased gradually until the final jump with anobvious increase in the velocity，during which its value is about104～106m/s. Furthermore，the current in the channel also increased with the leader moving forward，and the trend had ahigh coherence with the variation of the relative brightness of the leader，which is in good agreement with the research.Through the further simulation research of the wind turbine stroke by lightning with theapplication of the new3D self-consistent model under different condition，it was obtained thatturbine blade that at30°～45°angle can produce a stable upward leader a little earlier，inwhich condition the upward leader can grow a bit more quickly，compared with the conditionwhen turbine blade at other angle. Meanwhile we can find that when the turbine blade is at60°，the turbine may produce an upward leader obviously later than any other condition andthe leader also grows relatively more slowly.