On Singular Perturbations of Flexible and Variable-Speed Wind Turbines

Table 1

Parameters of the WECS mode.

Symbol	Description
𝑚𝑡	Mass of the tower
𝑚𝑝	Mass of each blade
𝐼𝑡	Inertia of the tower
𝐼𝑝	Inertia of blades
𝐽𝑟	Inertia of the rotor
𝐽𝑔	Generator inertia (low-speed side)
𝑘𝑡	Stiffness of the tower
𝑘𝑝	Stiffness of each blade
𝑘𝑠	Stiffness of the transmission
𝑁	Number of blades
𝑅	Length of each blade
𝐻	Height of the tower
𝑎	Length of the nacelle
𝐵𝑡	Damping of the tower
𝐵𝑝	Damping of each blade
𝐵𝑠	Damping of the transmission
𝐵𝑟	Rotor external damping
𝐵𝑔	Generator external damping
𝑛𝑔	Gearbox Ratio
𝐻𝑔	Distance to the mass center of the tower
𝑅𝑔	Distance to the mass center of the blade