Dynamic Response of a Wind Farm Consisting of Doubly-Fed Induction Generators to Network Disturbance - Simulation and Modeling Methodologies, Technologies and Application - page 128

Fig 4 depicts the maximum power tracking of a variable speed wind turbine at
different wind speed.

(Pitc h angle beta = 0 deg)

14.4 m/s

1.2

13.2 m/s

1

0.8

12 m/s

0.6

10.8 m/s

0.4

9.6 m/s

0.2

8.4 m/s

6 m/ s 7.2 m/s

0

0 0.5 1

Turbine Speed (pu)

Fig. 4. Maximum torque tracking of a variable speed wind turbine

2.3 The Mechanical Shaft System Model

Adequate model of the mechanical drive train is required when the study involves the
response of a system to heavy disturbances. It is better to represent the shaft by at
least two- mass model [12] as show in Fig 5 where the turbine is coupled to the
generator through a gearbox.

θ

1

θ

2

Fig. 5. Two mass model of the mechanical shaft system

From the figure, the following equations can be derived (10)-(17)

d

d ω

2

H

t

=− T Ts

(10)

t m 1

d

d ω

2

Hg

r

=− Ts T

(11)

2 e

Where,

2

J ω

J ω

2

g

H = and H =

T

(12) g T

2 2

2 nP 2 nP

pg g