【摘要】 雷电绕击是危及超高压输电线路安全稳定运行的主要原因。电气几何模型(EGM)及在其基础上的理论并未考虑雷电放电过程的分散性,现有的研究多限于仿真计算程序。针对超高压输电线路的雷电绕击进行了小模型实验,并充分考虑保护角、斜坡倾角、山涧高度、线路电压、雷击先导角、雷击先导点位置等因素影响,研究表明雷电绕击率与以上诸因素存在着隐含的复杂非线性关系。人工神经网络在任意连续函数的逼近能力及动态网络的稳定性分析方面具有优势,是预测雷电屏蔽非线性系统的最佳方法。基于广义回归神经网络GRNN逼近能力强,学习速度快,纠错性好的特点,用其来分析此非线性系统。在试验室模型试验的基础上利用Matlab进行了大量的仿真实验,验证了该方法的可行性与准确性。还分析了多种影响因素下GRNN的计算结果。更多还原

【Abstract】 Lightning shielding failure is the main factor to threat the safety and reliability of EHV transmission lines.The widely used electrogeometry model(EGM) and leader-progression model(LPM) don’t take into account the dispersivity of the lightning strike.Most of the studies nowadays,however,are limited in the scope of simulation calculation program.In this paper,the small-scale model experiments of lightning shielding failure performance of EHV transmission lines are made,taking the various influencing factors into account,including protection angle,the gradient of the hillside,the height of the gully,the conductor potential,non-vertical leader and the position of lightning stroke point,it is shown that the lightning stroke probability P_a has the hidden non-linear function relation with the factors above.Due to the superiority and stability of ANN to approach the random continuous function,it is the preferable tool for the computation of lightning shielding failure performance.Among the numerous ANN,the generalized regression neural network(GRNN) has several advantages over the back-propagation network(BP) such as very short training time and guaranteed performance even with sparse data,so it is applied to simulate the complex non-linear function relationship between the lightning stroke probability P_a and various influencing factors.On basis of the small-scale model experiments,a lot of simulation is carried out in Matlab and the feasibility and accuracy of the proposed GRNN are verified.With GRNN,the spatial distribution of P_a can be acquired under the various influencing factors with much less testing data.The result shows that terrain of hillside or deep gully increases the amplitude and spatial distribution of P_a remarkably. Smaller or even negative protection angle will be beneficial for that.The effect of non-vertical leader or applied voltage on P_a is also presented.更多还原