Environmental Engineering Reference
In-Depth Information
Fig. 1.11 Implementation of
PI controller with the
distributed anti-windup
set
v
pcc
Σ
k
p
u=
Qpcc
v
pcc
s
k
i
Σ
anti-windup
gain
k
i
k
p
Q
j
set
Q
j
max
Eq. 15
proposed distributed anti-windup is implemented in Matlab/Simulink [
18
]as
shown in Fig.
1.11
for case studies.
The attractive features of the supervisory reactive-power control scheme can be
summarized as follows: it does not require installation of additional compensating
devices, voltage regulation is achieved by controlling the available reactive power
that can be produced by each WT, dynamically changing operating state and limits
of each WT are taken into account, the supervisory control action stops auto-
matically for each individual WT whenever its limits have been reached, and the
scheme is very general and is readily extendible to multiple variable-speed WTs.
1.4 Case Studies
The system depicted in Fig.
1.1
was implemented in detail using the Matlab/
Simulink [
23
]. Computer studies considering the wind-speed variations, the local-
load variations, and the voltage sag due to the fault were conducted to compare the
dynamic responses of the system with different controls. In comparison, Mode 1
indicates the PFC-mode operation of the WT, which Q
set
g
is set to zero. As the
proposed operation, Mode 2 actively utilizes Q
set
g
for voltage control at the PCC.
1.4.1 Wind-Speed Variation
In this study, the wind speeds shown in Fig.
1.12
were considered for the WT.
Figure
1.13
shows the voltage at the PCC, predicted by the model with different
controls, respectively. As shown in Fig.
1.13
, Mode 1 operation caused the voltage
deviation about 3 %, which is much higher than the permissible voltage range of
HV power system network ± 2 %, while Mode 2 operation achieved the voltage
regulation at the PCC. Figure
1.14
shows the measured data of the active power
