Environmental Engineering Reference
In-Depth Information
Fig. 10.8 Reference and
output a generator torque
b stator reactive power
(a)
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
2
4
6
8
10
time [s]
(b)
0.1
0.05
0
−0.05
−0.1
0
2
4
6
8
10
time [s]
Fig.
10.10
a for the stator voltages (
' 2f
1
;
2
;
3
g
) and in Fig.
10.10
b for the stator
currents
(
' 2f
4
;
5
;
6
g
).
For
the
presentation
of
the
decision
functions
in
Figs.
10.10
a, b we have used the thresholds h
'
as normalization factor.
In Fig.
10.10
a, only g
1
, corresponding to fault in the sensor measuring u
s
;
a
crosses the threshold after t
¼
4 s. Therefore, this fault is correctly detected and
isolated. From Fig.
10.10
b, only g
6
, corresponding to fault in the sensor measuring
i
s
;
c
crosses the threshold after t
¼
8
:
5 s. Notice the repeated crossing of the
threshold while the fault is present, due to the re-initialization strategy in
Sect.
10.3.3
. The fault in sensor
' ¼
8(i
r
;
b
) produces positive values in g
'
for
' 2f
4
;
5
;
6
g
. In addition, changes in the reference and in the disturbance produce
transients of small amplitude in these decision functions. However, in both cases,
the decision functions do not cross the corresponding threshold. Again, we can
conclude that the fault in the stator current i
s
;
c
is correctly detected and isolated. In
addition for both faults are detected and isolated within the required detection/
isolation delay.
