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

随着风力发电机数量的不断增加，雷电对风车叶片的损伤成为一个严重的问题。虽然采用了避雷针、带棒塔等多种防雷方法，但在叶片尖端嵌入接地金属感受器以减少雷击损害，但效果不够。本研究提出了利用叶片周围空间电荷或表面覆盖水膜的更主动的保护方法，并通过对小型叶片模型施加雷击电压进行了验证。使用200- 300kv雷电冲击电压峰值得到如下结果：模型绝缘子表面被导线电晕放电产生的离子风带电。研究发现，当绝缘子上积累电荷的极性与外加电压极性相同时，放电通道在远离表面的地方形成，而放电则以相反极性向绝缘子周围延伸。当空间充电电压极性与冲击电压相同时，闪络电压升高50%，极性相反时闪络电压降低50%。从防雷的角度出发，除了利用表面电荷效应和空间电荷效应外，还开发了一种利用水膜覆盖介电材料表面的防雷方法。当水的电导率小于1微S/cm时，在水表面产生放电。在这种情况下，至少在0.25毫米厚的水膜上没有观察到水的破裂。而当水膜更薄、电导率更高时，放电电流直接在水中流动，在击穿点附近表面放电不扩大。

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.