Table 2 Nomenclature

P_w:

Wind turbine power

P_m:

Extracted mechanical power

ψ_PM:

Permanent magnet flux

S:

Sliding surface

i_dq:

Direct and quadrature currents

C_p:

Power coefficient

ω_r,e:

Mechanical and electrical speeds

λ:

Tip speed ratio

R:

Radius of the wind turbine rotor

ρ:

Air density

V_dq:

Direct and quadrature voltages

V_w:

Wind speed

L_dq:

Direct and quadrature inductance

R_s:

Stator resistance

T_m,e:

Mechanical and electrical torques

e:

Error

B:

Viscus friction coefficient

J:

PMSG inertia

A:

Swept area of the wind turbine

γ:

Positive constant matrix

V_αβ:

PMSG voltage in α−β coordinate

x_ref:

Reference Value

e_αβ:

PMSG back-EMF in α−β coordinate

x:

Controlled variable

i_αβ:

PMSG current in α−β coordinate

L:

PMSG inductance

y:

Controlled variable

h:

Step size

K_,ω,d,q,Y,Z,k and c: Constants