Atmospheric pressure plasma shield for protecting wind power generator from lightning stokes

随着风力发电机数量的增加，风力发电机叶片的雷击破坏问题日益严重。虽然许多类型的防雷方法，如避雷针和带杆的塔，接地的金属受体嵌入在叶片的尖端已经安装，以减少雷击损害，但没有足够的效果。在这项研究中，更积极的保护方法，利用叶片周围的空间电荷或表面覆盖的水膜已被提出，并通过施加雷电冲击电压的小叶片模型进行了检查。采用200-300 kV的雷电冲击电压，通过导线电晕放电产生的离子风对模型绝缘子表面充电，得到了如下结果：结果表明，当绝缘体上积累的电荷极性与外加电压极性相同时，放电通道远离表面形成，而当电压极性相反时，放电通道沿绝缘体周围扩展。当电压极性与冲击电压相同时，空间电荷使50%闪络电压增大，当电压极性相反时，空间电荷使50%闪络电压减小，从防雷角度考虑，除了表面和空间电荷效应外，还提出了在介质材料表面覆盖水膜的方法。当水的电导率小于1 μ S/cm时，在水的表面上产生放电。在这种情况下，至少在超过0.25mm厚度的水膜上没有观察到水击穿。而当水膜较薄且电导率较高时，放电电流直接在水中流动，沿面放电不会在击穿点附近扩展。

With increase in number of wind power generators, the lightning damage on the windmill blade becomes a serious problem. Although many types of lightning protection methods such as a lightning rod and a tower with rod, a grounded metal receptor embedded in a tip of the blade have been installed to reduce the lighting damage but have not sufficient effect. In this study, more active protection method using space charge around the blade or water film covered on the surface has been proposed and examined by applying lightning impulse voltage to the small blade models. The following results are obtained using lightning impulse voltage having 200-300 kV peak values.The surface of model insulator was charged by the ion wind generated by the wire corona discharge. It was found that the electric discharge channel was formed away from the surface when the polarity of the accumulated charge on the insulator was same as the applied voltage polarity, while the discharge extended around the insulator with opposite polarity. 50% flashover voltage increased when the space charge that voltage polarity was same to the impulse voltage, while decreased when the polarity reversed.In addition to the surface and space charge effect from the view point of the lightning protection, another method was developed using water films covering the surface of the dielectric materials. The discharge developed on the surface of the water when the conductivity of the water was smaller than one micro S/cm. In this case, the water breakdown was not observed at least over 0.25 mm thickness of water film. But with thinner and higher conductivity water film, the discharge current flowed in the water directly and the surface discharge was not expanded around the breakdown point.