Abstract
Lightning accidents seriously threaten safe operation of wind turbines because the influence mechanisms of wind turbine rotation on corona and upward leader initiation are, so far, not clear. A three-dimensional stochastic evolution model of the lightning downward leader was established by combining the dielectric breakdown model and the lightning current shunt method, according to which the charge density distribution of leader branches was determined. The corona and leader initiation mechanisms of rotating wind turbine were studied based on the 3D drift and diffusion model of ion flow in the neighboring space of a rotating wind turbine. The results show that due to blade rotation, the charged particles are unevenly distributed near the blade tip and the contours are in a strip-like shape. As the rotating speed increases, the blade tip is more susceptible to initiating corona discharge. Combining the three-dimensional stochastic development model of the lightning downward leader and ion distribution model near a rotating wind turbine, the initiation direction of the upward leader was analyzed, and in 66% of cases, the initiation direction of the upward leader on the blade tip was on the back side of the blade rotation.
Highlights
Francesco CastellaniThe development of large wind farms is the strategic direction of the power system to support the realization of “peak CO2 emission and carbon neutrality”
Wind farms are usually located in prominent positions, and wind turbines are prone to be threatened by lightning strikes with their tall structures
Under the effects of a thundercloud induced electric field and the lightning downward leader (DL), the corona discharge initiated on the blade tip will further develop into the upward leader
Summary
The development of large wind farms is the strategic direction of the power system to support the realization of “peak CO2 emission and carbon neutrality”. In order to further study the actual effect of WT rotation on the discharge process of the blade tip, Qu et al [7] calculated the charge distribution close to a single blade receptor of a WT under the influence of a thundercloud’s electric field and analyzed the effect of wind speed on the space charge distribution. Under the effects of a thundercloud induced electric field and the lightning downward leader (DL), the corona discharge initiated on the blade tip will further develop into the upward leader. Combining the 3D stochastic development model of the lightning downward leader and ion distribution model near rotating WT, the initiation process of the upward leader from the blade tip was analyzed. The WT model was established according to the actual operating WT’s geometry, and since the blade tip is a metal structure, the rotating impeller has a lightning shielding effect on the WT tower under the thundercloud. Mesh structures were set at the boundary of the rotating and stationary domains
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