Lightning accidents seriously threaten the safe operation of wind turbines due to the unclear initiation mechanism of the airborne lightning-induced discharges on turbine blades, in which turbine rotation is one of the principal influencing factors. To study the impact mechanism of wind turbine rotation on corona discharge inception, a numerical model with the dynamic meshing of charged ions in the neighboring space of a large-scale rotating wind turbine during a thunderstorm was established in this article, and the validity of the model was verified by long gap discharge experiments on a scaled wind turbine. Based on the proposed model, the spatial and temporal distributions of charged particles in the neighboring area of the rotating wind turbine and the space charge-caused local electric field distortion scenario were obtained. The influence mechanism of blade rotation on corona discharge inception was further analyzed and elucidated accordingly. The results indicate that the charged particles are unevenly distributed near the rotating blade tip, and the contours present a strip-like shape, the critical area of which may facilitate corona discharge inception. As the blade speed increases from 6 to 20 rpm, the E-field extremum at the blade tip increases by 38%, causing the blade tip prone to initiate corona discharge. The critical rotating speeds corresponding to corona inception probability were calculated under different thundercloud-determined field strengths, and a safe boundary was defined, by which it is recommended that wind turbines operate at a reduced speed below 8 rpm under thundercloud conditions.
- charge density descent vector
- corona discharge
- ion flow distribution
- rotating blade
- wind turbine