Dynamic Response of a Wind Farm Consisting of Doubly-Fed Induction Generators to Network Disturbance - Simulation and Modeling Methodologies, Technologies and Application - page 134

where k , 1 i k are the q axis PI proportional and the integral constant k , k are the d

1 p 2 p 2 i

* *

axis PI proportionality and integral constant respectively.

v are the reference
voltages that generate the command for the grid side PWM converter after conversion
to abc frame.

v

and

1

*
i is derived from the grid reactive power error while

i

*
d

is derived

from the dc link voltage error as shown in Fig.10.
Applying the grid voltage oriented control i.e. aligning the d axis of the reference
frame along the grid voltage vector, then q v0 .

Hence, active and reactive power can be written as (41) and (42)

=

Pv i
2

(41)

=

g d d

3

Q =− v i

(42)

g d q

2

i

The reactive power can be controlled by the q of the grid side converter. The energy

stored in the dc link can be written as (43).

1 cv
2

2
dc

(43)

Where c and v are the dc link capacitor and voltage respectively

dc

d

cv v =− P P

(44)

dc dc g r

dt

P

cv P

g

=−=−

r

i i

(45)

dc og or

dt v v

dc dc

where

3 v

i =

d

i

og d

2v

dc

v m

d

=

(46)

v

2

2

dc

where m is the modulation factor which gives the ratio of grid voltage to the dc bus
voltage [18].

d 3m

cv = i − i

(47) dc d or

dt

4

2

i can be used for the control of dc bus voltage.

Hence,