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
5
THD of i a =5.22%
THD of i a =5.39%
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) Grid output current
harmonic spectra
Figure 16.7 Experimental results for a PR controller with an unbalanced resistive local load imple-
mented in the αβ frame (left column) and in the abc frame (right column)
current i a and its spectra, the reference current i ref and the corresponding current tracking error
e i in the steady state are shown in the left column of Figure 16.7 for the implementation in
the
frame and in the right column of Figure 16.7 for the implementation in the abc frame.
The tracking performance of the PR controller implemented in the
αβ
frame was remarkably
worse than the one implemented in the abc frame, although the recorded THD in the
αβ
αβ
frame
was slightly better than that in the abc frame.
16.4.1.4 With a Non-linear Load
In this experiment, a three-phase uncontrolled rectifier loaded with an LC filter L
=
150
μ
H,
C
was connected to the system. The grid current output
i a and its spectra, the reference current i ref and the current tracking error e i are shown in the
left column of Figure 16.8 for the implementation in the
=
1000
μ
F and a resistor R
=
20
frame and in the right column of
Figure 16.8 for the implementation in the abc frame. While the tracking performance in both
frames were quite similar, the current THD in the abc frame was slightly better than that in
the
αβ
αβ
frame.
16.4.2 Transient Performance
In this experiment, a step change in the current I d
reference from2Ato3Awasapplied
(while keeping I q
=
0). The grid current output i a , the current reference i ref and the tracking
 
Search WWH ::




Custom Search