Observation And Research On Lightning Strike Patterns Of Wind Turbines And Wind Turbine Group

As a clean energy source,wind power generation has received increasing attention from governments around the world in recent years.Lightning strikes are one of the main causes of damage to wind turbines,which are wind power generation facilities.This paper studies the characteristics and types of thunderstorms when wind turbines are prone to lightning strikes,analyzes the distribution characteristics of lightning strikes in different distribution forms of wind turbine clusters,reveals the physical mechanism of lightning strikes in wind turbine clusters through simulation,and further studies the impact of the rotation of wind turbine on lightning strikes through controlled wind turbine experiments.The main conclusions are as follows:1.The lightning stroke characteristics of three wind turbine clusters with different distribution(linear,cluster)and locations(mountain and ocean)were compared and analyzed.After the installation of the wind turbine clusters,they can attract more strokes and affect the distribution of strokes in the surrounding area.The increase rate of return stroke density and the impact range of linear distributed wind turbine cluster is greater than that of cluster distributed wind turbine cluster.The return stroke density,cloud to ground flash density and average peak current in the cluster distribution wind turbine cluster at sea increased by 10.1%,11% and 5.1% respectively,but the lightning multiplicity changed little.The inner and outer areas show different lightning strike characteristics.The return stroke density,lightning multiplicity and average peak current of the outer region increased by 21%,4.1% and 6.8%respectively,while the inner region decreased by 20.2%,19% and 3.9% respectively.The cloud to ground flash density in the outer area increased by 16.1%,but the change in the inner area was very small.The simulation results show that there are significant differences in the potential distribution between the inner and outer regions: at the higher altitude,the distortion effect of the outer side wind turbines on the space potential are stronger than that of the inner side wind turbines.But at the lower altitude,the difference is not obvious.This difference in potential distribution leads to different characteristics of lightning strikes between inner and outer areas.2.The analysis of a thunderstorm process through a linearly distributed wind farm shows that all of the lightning strokes detected on the wind turbine are downward negative cloud-to-ground flashes,and the average peak current is higher than the average peak current of the entire region.With the development of thunderstorms,the thunderstorm charge structure gradually develops into a tripolar charge structure and then gradually becomes a dipole charge structure.Lightning strikes on wind turbines mainly occur in the mature stage of thunderstorms.At this time,thunderstorms present an obvious tripolar charge structure,and there is an obvious high and stable lower positive charge region at the height of 4 to 5.5 km.The presence of a moderate lower positive charge region leads to downward cloud-to-ground flashes on wind turbines.3.A wind turbine test device with controllable rotation has been developed and constructed,and unmanned aerial vehicle electric field sounding tests have been conducted to explore the impact of blade rotation on the electric field.The results show the near surface electric field profiles under sunny weather and thunderstorm conditions.In sunny weather,the atmospheric electric field is negatively correlated with altitude.During thunderstorms,the atmospheric electric field is positively correlated with altitude.It is found that when a wind turbine rotates,the adjacent spatial electric field above its blades becomes stronger,and the spatial electric field is positively correlated with the rotational speed of the wind turbine.With the linear speed of the wind turbine unchanged(taking the linear speed of 52 m/s as an example),the spatial electric field adjacent to the wind turbine above the wind turbine decreases as it moves away from the blade,and the significant range of spatial electric field that the blade can affect is about 3.5 m.