不同旋转角度下风机叶尖电晕放电空间电荷分布仿真分析

Simulation and Analysis on Distribution of Space Charge of Wind Turbine Blade Tip Corona Discharge at Different Rotation Angles

针对目前风力发电机叶尖附近空间电荷的分布特性不明确等问题,笔者利用仿真建模手段对风机叶片处于不同旋转角度时叶尖电晕放电进行了仿真研究,将风机叶片旋转时叶尖与周围空气的相对运动等效为叶尖流过的高速气流,考虑正极性离子与其他离子的附着与碰撞作用,建立了一种二维正极性电晕放电空间电荷分布模型;基于上述模型,得到了风机叶片旋转到不同角度时叶尖电晕放电正极性空间电荷的分布特性和以及正离子迁移规律。研究发现,在雷云电场作用下,由于风机叶片旋转时叶尖流过的高速气流提供给空间电荷的迁移速度远大于电场牵引力提供的迁移速度,因此叶尖电晕放电空间电荷的迁移扩散方向主要由叶尖高速气流的方向决定,此时在空间中不再呈对称分布的空间电荷使空间电位发生了畸变,使得同等高度下,叶尖接闪器左侧(迎风侧)电位高于右侧电位,且叶尖接闪器附近最大电场的方向向左侧偏移,且较静止工况时电场幅值也有所增加。本研究可为风机叶片上行先导起始和发展计算提供基础,为旋转风机叶片雷电防护系统设计提供理论依据。

Aiming at the problem of unclear distribution characteristics of space charge near blade tip of wind turbine,the author adopted simulation modeling method to simulate corona discharge of blade tip at different angles.The relative motion between the blade tip and the surrounding air when the wind turbine blade is rotating is equivalent to the high-speed air flow through the blade tip.Considering the attachment and collision between positive ions and other ions,a two-dimensional positive corona discharge space charge distribution model was established.Based on the above model,the blade tip corona dis-charge was simulated and the distribution and migration characteristics of positive space charge were obtained when the blades at different angles.It is found that,under the lightning electric field and high-speed air flow,the transfer velocity of space charge provided by the high-speed airflow flowing through the blade tip is much higher than that provided by electric field traction,therefore,the transfer and diffusion direction of space charge in the blade tip is mainly determined by the direction of the high-speed airflow at the blade tip.At the same time,the space charge no longer symmetrically distributed in space causes space potential distortion,the potential on the left side(windward side) of the blade tip air-termination is higher than that on the right side at the same height,and the direction of the maximum electric field near the blade tip air-termination shifts to the left,and the electric field amplitude also increases compared with that in the static condition.The work carried out in this paper can provide a basis for the initiation and development calculation of upstream pilot of wind turbine blades,and provide a theoretical basis for the design of lightning protection system of wind turbine blades.