Abstract: Wind energy is recognized as a clean and renewable energy source and plays a crucial role in achieving the “dual carbon” goals and facilitating the transition to a low-carbon energy system. To optimize power generation efficiency, wind turbines are typically installed in exposed areas, such as mountaintops or offshore locations, where the probability of lightning strikes is elevated and the associated damage is significant. Research on lightning strike patterns on affecting wind turbines is considered vital for enhancing lightning protection capabilities.
The wind farm under observation consists of 9 wind turbines, each equipped with a 115-m towers and 99-m blades. 3-dimensional total-flash lightning mapping and synchronized waveform observations are conducted using Realtime Low-frequency Electric Field Detection Array (RT_LFEDA) at China Meteorological Administration’s Field Experiment Base on Lightning Science (CMA_FEBLS). Radiation source data in terms of azimuth and elevation angles for lightning strikes on turbines are obtained with a lightning continuous interferometer (CINTF).
It is shows that the mountainous wind farm exhibits an attraction effect on nearby cloud-to-ground return strokes. An influence range of approximately 1.8 km is observed, within which the lightning strike density is elevated. The return stroke density decreases from 3.7 km^-2 near turbines to 1.5 km^-2 outside the influence zone, with an average value of 2.53 km^-2. Multiple return strokes from a single flash are observed to strike different turbines, and these strike locations correlate closely with branched paths of the initial downward leader. Subsequent discharges develop along different leader branches, leading to return strokes at spatially separated positions. Furthermore, strong and weak return strokes exhibit distinct spatial distributions: Stronger return strokes being tend to occur on turbines located at lower elevations along the periphery of the wind farm. Upward leaders are initiated from multiple wind turbines during lightning events, and their initiation is observed to take place when the downward leader approaches within 100-200 m of a turbine. Lengths of upward leaders are measured to range from 161 m to 356 m, with propagation speeds between 1.8×10⁵ m·s^-1 and 2.2×10⁶ m·s^-1, and an average speed of 1.03×10⁶ m·s^-1. The average propagation speed of connecting leaders is 1.7×10⁶ m·s^-1. Electric field waveforms of return strokes are characterized by multiple peaks due to current reflection caused by the turbine structure, with an average peak-to-peak interval of 4.66 μs. The presence of reflected signals is considered to lead to overestimation of lightning current by operational lightning location systems for strikes on wind turbines.