不同间隙尺度下叶片旋转对风力发电机引雷能力影响的试验研究

Experiment of Blade Rotation on Lightning Strikes of Wind Turbines at Different Gap Scales

风力发电机正常运行时,叶片处于转动状态,叶片转动可能会对风力发电机的雷击过程产生一定的影响。为研究这一问题,设计满足试验需求的缩比风机放电试验平台,开展间隙距离为1~8m单风机放电试验和双风机选择性放电试验,并利用高速摄影仪和单反相机进行观测,获取了不同间隙下静止和旋转缩比风机的50%冲击放电电压和接闪概率,以及上行先导发展长度、起始时间和发展速度。试验结果表明:间隙距离1~2m的单风机放电试验中,其击穿电压随叶片转速的提升而提升,叶片转动导致风机的接闪能力降低;间隙距离4~8m的单风机放电试验中,击穿电压随叶片转速的提升而降低,叶片转动导致风机的接闪能力升高。双风机选择放电试验验证了这一规律。对放电过程进行高速观测发现,较短间隙距离下,上行先导发展长度随风机转速增大而减小,较长间隙距离下则结果相反。另外,对于8m间隙距离下,叶片旋转使上行先导起始提前,先导发展速度随着叶片转动影响不明显。基于试验结果开展理论分析,认为叶片的转动会减小叶尖附近电晕放电的空间电荷密度,进而导致靠近风机叶尖区域场强提升,远离风机叶尖区域场强降低。短间隙和长间隙下的影响程度不同,从而出现短间隙和长间隙试验中出现的相反规律。所得结果可为风电机组的防雷保护提供参考借鉴。

In the normal operation of the wind turbine, the blades are turning. To study the influence of blade rotation on the lightning attracting ability of wind turbine, a discharge test platform for scaling wind turbine meeting the needs of test was designed. The 50% impulse voltages and flash probabilities of scaling wind turbine with different gap distance in static and rotary conditions were obtained by discharge test and selective discharge test for scaling wind turbine with 1-8 m gap distance. High-speed camera and SLR camera were used for observation, and the development length, start time, and development speed of the upward leader were calculated. The test results show that in the discharge test of single wind turbine with gap distance of 1-2 m, the breakdown voltage of the scaling wind turbine increases with the increase of the blade rotation speed. While in the discharge test with gap distance of 4-8 m shows that the breakdown voltage of the fan decreases with the increase of the blade rotation speed. The test results prove the double scaling wind turbine experiment have the same rules. The high-speed observation of the discharge process shows that the length of the upward leader development decreases with the increase of the wind turbine speed at a short gap distance, and the opposite result occurs at a longer gap distance. In the discharge test of single wind turbine with 8 m gap distance, the observation shows that blade rotation advances the start of upward leader, and the development speed of upward leader has no obvious influence with the blade rotation. The theoretical analysis was carried out to explain the phenomenon that the rotation of the wind turbine will reduce the space charge density near the area, leading to the increase of the field strength close to the tip area of the wind turbine and the decrease of the filed strength far away from the tip area of the wind turbine. The short and long gaps have a different degree of influence, resulting in the opposite phenomenon of the short and long gaps. The results can provide reference for lightning protection of wind turbine.