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
15
15
THD of i
a
=14.84%
THD of i
a
=16.02%
10
10
5
5
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 15.6
Experimental results for a PI controller with a balanced non-linear local load implemented
in the
dq
frame (left column) and its equivalent in the
abc
frame (right column)
15.3.2 Transient Performance
In this experiment, a step change in the current
I
d
reference from2Ato3Awasapplied (while
keeping
I
q
0) in the grid-connected mode without a local load. The grid current output
i
a
,
current reference
i
ref
and tracking error
e
i
are shown in Figure 15.7. The PI controllers
demonstrated fast dynamics, following closely the reference signal
i
ref
.
=
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
−0.04
−0.03
−0.02
−0.01
0
0.01
0.02
0.03
0.04
−0.04
−0.03
−0.02
−0.01
0
0.01
0.02
0.03
0.04
Time [s]
Time [s]
Figure 15.7
Transient response of the PI controller in the grid-connected mode without a local load
implemented in the
dq
frame (left column) and its equivalent in the
abc
frame (right column)
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