A New Identification Method for Bolt Looseness in Wind Turbine Towers

Table 2

Description of the horizontal vibration measuring points in the prevailing wind direction of each wind turbine tower.

Measuring point ID	Arrangement position	Point elevation of the No. 1 and No. 2 wind turbine towers (m)	Point elevation of the No. 3 to No. 6 wind turbine towers (m)
1	Bottom of the wind turbine tower	0	0
2	Middle of the first section	6	8
3	Top of the first section (bottom of the first flange plate)	12	16
4	Bottom of the second section (top of the first flange plate)	13	17
5	Middle of the second section	26	28
6	Top of the second section (bottom of the second flange plate)	40	40
7	Bottom of the third section (top of the second flange plate)	41	41
8	Middle of the third section.	49	50
9	Top of the third section (bottom of the third flange plate)	58	60
10	Bottom of the fourth section (top of the third flange plate)	59	61
11	Middle of the fourth section	66.5	70
12	Top of the fourth section	75	80