Evaluation of Lightning Fault Rate of Transmission Line on the Coastal Area of the Sea of Japan in Winter

Probability of lightning hits to tall structures taking account of upward lightning

“…The estimated double-circuit outage rate of a fictitious 500 kV transmission line with the average tower height of 90 m is 1.5 to 2, based on Fig. 1 and 2 [10]. This number far better agrees to the actual performance than that of the conventional prediction model, which only postulates downward lightning strokes.…”

Frequency of Upward Lightning Hits to Wind Turbines in Winter

“…(4) and the increase rate (l ei ) estimated by Eq. (9). The correlation coefficient of 0.07 obtained with Eq.…”

“…l i (km 2 ) is the rate at which the number of strikes per unit density detected by the LLS in the hot spot area increases due to the presence of high structure. The dimension is km 2 because formally, this value expresses the area in which lightning strikes concentrate, just as in the case of the previously defined lightning rate [9]. Table 1 lists 10 locations with high increase rates of upward lightning strikes observed by the JLDN in winter on the Sea of Japan side of Honshu.…”

“…3) improves to 0.86 when using Eq. (9). The decline in the increase rate can be attributed to factors such as the distance from the coastline, the surrounding terrain, the prevailing wind direction, and so on.…”

“…We set the surrounding areas and hot spot area as squares, 9 km and 3 km on a side, respectively, but l i and N u remained unchanged as the size of the surrounding area and hot spot area were varied, so long as upward strikes (N u ) were observed only within the hot spot area, and the surrounding density D b was the same. However, the parameters of lightning discharges depend on the distance from the coastline of the Sea of Japan . Thus, the lightning density, current distribution, and polarity ratio are affected by the distance.…”