Lightning Environmental Assessment of an Offshore Wind Farm Site Area

In order to assess the natural lightning environment at an offshore wind farm site off the southern coast of China, a statistical study of lightning characteristic parameters is carried out. Such as thunderstorm days, spatial distribution of CG flash density, accumulation probability of lightning current amplitude and their sea-land differences are analyzed using the Lightning Location System (LLS) data from 2016 to 2021. The wind farm site is located in a subtropical maritime climate zone with obvious regional and temporal characteristics of lightning activity. It is an area of high lightning activity, with an annual average of 109 thunderstorm days. Where it is in the coastal area of Guangdong Province, the CG flash density between sea and land is obviously different, showing a distribution trend of land>offshore> distant sea. The average annual CG flash density within the offshore wind farm and the 5 km buffer zone is 1.43 flashes/km
²
year, while the average annual ground lightning density within 5 km of the onshore converter station is 2.15 flashes/km
²
/year, which is consistent with the distribution pattern of CG lightning density in the surrounding areas. On the other hand, the average lightning current amplitude within the offshore wind farm is 50.87 kA, while within the onshore converter station is 40.36 kA, both of which are higher than 28.8 kA in Guangdong Province. Therefore, it is necessary to strengthen the protection measures against direct lightning strikes for this offshore wind farm, to improve the lightning resistance level of the turbines and converter stations.