Seismic Vibration Mitigation of Wind Turbine Tower Using Bi-Directional Tuned Mass Dampers

Table 1

The modal parameters of the LFEM and CBFEM.

Mode	LFEM		Mode	CBFEM
	Mode shape	f (Hz)		Mode shape	f (Hz)
1	1^st tower side-to-side	0.3347	1	1^st tower side-to-side + 1^st blade edgewise	0.3287
2	1^st tower fore-aft	0.3348	2	1^st tower fore-aft + 1^st blade flap-wise	0.3314
3	2^nd tower side-to-side	1.7534	3	2^nd tower side-to-side + 1^st blade edgewise	1.3973
4	2^nd tower fore-aft	1.7535	4	1^st blade torsion	1.4678
5	3^rd tower side-to-side	4.8185	5	2^nd tower fore-aft + 1^st blade flap-wise	1.5294
6	3^rd tower fore-aft	4.8203	6	2^st blade torsion	2.7268