Environmental Engineering Reference
In-Depth Information
200
K
i
=25
K
i
=50
K
i
=200
K
i
=500
100
0
−100
180
0
−180
−360
10
1
10
2
10
3
10
4
Frequency (rad/sec)
Figure 16.4
Bode plots of the open-loop system for different
K
i
with
K
p
=
1.12
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
5
THD of i
a
= 4.14%
THD of i
a
=3.84%
4
4
3
3
2
2
1
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 16.5
Experimental results for a PR controller without a local load implemented in the
αβ
frame
(left column) and in the
abc
frame (right column)
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