Fatigue Life Evaluation of Wind Turbine Tower Based on Measured Data

Table 1

Definition of operational states for wind turbines.

LC	Operational state	Wind speed (m/s)	Rotation speed (rpm)	Pitch angle (°)
LC 1	Shutdown	0–22	0–3	75–90
LC 2	Standby	0–10	0–3	49–50
LC 3	Transition of startup and shutdown	0–3	2–9	±0
LC 4	Grid-connected rotation speed	1–6	9–10.5	±0
LC 5	Medium rotation speed	3–9	10.5–16	±0
LC 6	Rated rotation speed	11	16–18.38	0–20
LC 7	Cutout wind speed	>22	0–4	75–90