Digital Signal Processing Reference
In-Depth Information
300
μ(
X
)
250
μ(
X
)
1
200
X
150
0
300
100
X
0
X
min
X
X
100
300
m
max
100
0
10
20
30
40
50
60
70
80
90
Time,
t
[ms]
Fig. 11.23
Illustration of signal fuzzification (reactance X)
μ(
I
L
)
μ(
I
0
)
μ(
R'
)
B
1
1
I
obc
I
0
Δ
X
μ(
R'
)
μ(
I
L
)
μ(
I
0
)
μΔ
(
X
)
B
2
2
I
obc
I
0
Δ
X
Δ
X
μ(
R'
)
μ(
I
L
)
μ(
I
0
)
B
8
8
R'
F
Δ
X
R'
(
n
)
I
0
(n)
I
0
I
L
(n)
I
obc
min
Fig. 11.24
Illustration of the fuzzy inference process
Using the data from EMTP simulations two sets of IF-THEN rules have been
obtained. The rules (block 5) have been defined separately for positive and
opposite direction of fault current (in relation to the pre-fault flow). The fuzzy
reasoning process is shown in Fig.
11.24
.
For defuzzification of MF l
B
(X) the centre of area method is used (block 6 in
Fig.
11.22
). As a result of this process a non-fuzzy value of the corrective
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