Environmental Engineering Reference
In-Depth Information
5
5
i
ref
i
a
i
ref
i
a
2.5
2.5
0
0
−2.5
−2.5
−5
−5
1.5
1.5
e
i
e
i
1
1
0.5
0.5
0
0
−0.5
−0.5
−1
−1
−1.5
−1.5
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
Time [s]
Time [s]
(a) Grid output current
, its reference
and current tracking error
5
15
THD of i
a
=5.54%
THD of i
a
=16.54%
4
10
3
2
5
1
0
0
0
5
10
15
20
25
30
0
5
10
15
20
25
30
Harmonics order
Harmonics order
(b) Spectra of the grid output current
Figure 17.4
Experimental results for a DB controller with an unbalanced local load (left column) and
with a non-linear local load (right column)
Table 17.3
Comparison of current controllers in the grid-connected mode with an
unbalanced local load
Controller
Current
i
a
THD [%]
Grid Voltage
v
ga
THD [%]
H
∞
Repetitive
1
.
55
1
.
59
PR
5
.
39
1
.
45
PI
5
.
03
1
.
48
DB
5
.
54
1
.
52
Table 17.4
Comparison of current controllers in the grid-connected mode with a
non-linear local load
Controller
Current
i
a
THD [%]
Grid voltage
v
ga
THD [%]
H
∞
Repetitive
4
.
91
1
.
60
PR
16
.
71
1
.
47
PI
16
.
02
1
.
41
DB
16
.
54
1
.
49
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