Comparison of Lightning Flash Density Observed by LLS and Current Measurement in Japan in Winter

Abstract:
Wind farms (WFs) have been developed near the coast of the Sea of Japan for the condition suitable for power generation, however, this area is notable for lightning activity in winter. The influence of the development of WFs at the distance of 1.2 km or less on the lightning flash density is investigated based on the located data by the Japanese lightning detection network (JLDN), the largest lightning location system (LLS) in Japan. The authors have carried out measurement of the current waveforms associated with lightning discharges to wind turbines (WTs) at three WFs in the area. The yearly variation of lightning flash density at one WF estimated by the JLDN agrees fairly well with the variation evaluated based on the current measurement. The lightning flash density at three WFs evaluated by the current measurement in winter season from 2021 to 2022 is compared and it is found that the lightning flash density observed by the JLDN qualitatively agrees with the results evaluated based on the current measurements. The agreement of the flash density estimated by the JLDN and evaluated by the current measurement at some WTs demonstrates the validity of the estimation of the lightning flash density.