雷击风机叶片的跃变击距特性与定量表征

风机叶片对雷电的接闪是风机防雷研究中的关键内容,合理分析接闪时的击距特性意义重大。基于雷击过程的物理机制,将雷击发生时上、下行先导头部间的距离定义为跃变击距,并分析了多上行先导竞争对风机接闪和跃变击距的影响。基于先导起始和发展理论,根据下行先导的等效模型和稳定上行先导的判定方法建立了风机叶片接闪模型,利用该模型得到了随雷电流幅值变化的跃变击距公式,指出侧面距离等参数对跃变击距没有影响,实验和观测结果证明了模型的正确性。最后利用接闪模型提出了考虑稳定上行先导对周围电场畸变作用的对地击距公式,与其他学者计算的结果进行对比指出,现有对地击距公式或不适用于风机背景的防雷计算。

Quantitative Characterization of the Striking Saltus Distance of Wind Turbine Blade

Lightning attachment to wind turbine blade is a key process of research about lightning protection of blades.An appropriate analysis of striking distance is beneficial for the lightning attachment research.Based on the physical mechanism of lightning attachment process,the distance between the heads of downward leader and connecting upward leader was defined as striking saltus distance.The influence of multiple upward leaders on lightning attachment and striking saltus distance was then analyzed.Considering the leader inception and propagation theory,a lightning attachment model of wind turbine blade was established according to equivalent model of downward leader and the judgement method of stable upward leader.Furthermore,a striking saltus distance equation was proposed using model and results show that the lightning parameters,such as lateral distance,have no effect on striking saltus distance.Experimental and observational results were used to verify the model.Moreover,a striking distance equation to ground was proposed considering the influence of upward leaders to the electric field.Comparative analysis indicates that the existing equations are maybe ineffective for lightning calculation of wind turbines.