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10
8
6
4
Ipv
I*
2
0
0
20
40
60
80
100
120
140
160
180
Sampling period
0.8
Duty Cycle
0.6
0.4
0.2
0
0
20
40
60
80
100
120
140
160
180
Sampling period
Fig. 5.
The Current tracking and Duty Cycle
of the sub-interval N=2. As Fig.5 shows, though oscillates at first, the output
current could track the reference current I*, even I* fluctuates form 4A to 9A
suddenly.
In order to validate the proposed control methodology, simulation and exper-
iment based on the data of light intensity and temperature were carried out on
the photovoltaic system of SJTU showed in Fig.6.Fig.7 shown the Light intensity
and temperature measured every 5mins form 7.a.m. to 17.p.m on July.21 2012.
Fig. 6.
Photovoltaic system owned by Department of Automation, SJTU
Based on the data of light intensity and temperature, MPP could be calcu-
lated by the proposed T-G-P model. After measuring the PV output voltage
(it changes form 14.8V to 17.2V very slowly), which can be regarded as con-
stant in one sampling time, the MPPT reference output current I* is clear. In
Fig.8, though the charge-discharge of energy-storage elements may lead to the
oscillation of output current (the blue line) during the regulation procedure, the
output current could track the reference current (the red line) well, more im-
portantly, the output power (Pout, the blue line) follows the MPP (the red line)
perfectly.
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