ABSTRACT:
This paper proposes a new solar power generation system,
which is composed of a dc/dc power converter and a new seven-level inverter.
The dc/dc power converter integrates a dc–dc boost converter and a transformer
to convert the output voltage of the solar cell array into two independent
voltage sources with multiple relationships. This new seven-level inverter is
configured using a capacitor selection circuit and a full-bridge power converter,
connected in cascade. The capacitor selection circuit converts the two output
voltage sources of dc–dc power converter into a three-level dc voltage, and the
full-bridge power converter further converts this three-level dc voltage into a
seven-level ac voltage. In this way, the proposed solar power generation system
generates a sinusoidal output current that is in phase with the utility voltage
and is fed into the utility. The salient features of the proposed seven-level
inverter are that only six power electronic switches are used, and only one power
electronic switch is switched at high frequency at any time. A prototype is
developed and tested to verify the performance of this proposed solar power
generation system.
KEYWORDS:
1.
Grid-connected
2.
Multilevel
inverter
3.
Pulse-width
modulated (PWM) inverter
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig. 1. Configuration of the proposed solar power generation system.
EXPECTED SIMULATION RESULTS:
Fig.
2. Simulation results of the proposed solar power generation system: (a) utility
voltage, (b) negative terminal voltage for adding the symmetric filter
inductor, and (c) negative terminal voltage for adding the symmetric filter
inductor and the extra filter Cf –Rf –Cf
.
Fig.
3. Experimental results for the ac side of the seven-level inverter:
(a)
utility voltage, (b) output voltage of seven-level inverter, and (c) output
current
of the seven-level inverter
Fig.
4. Experimental results for the dc side of the seven-level inverter:
(a)
utility voltage, (b) voltage of capacitor C2, (c) voltage of capacitor C1,
and
(d) output voltage of the capacitor selection circuit.
Fig.
5. Experimental results of the dc–dc power converter: (a) ripple current of
inductor, (b) ripple voltage of capacitor C2, and (c) ripple voltage of
capacitor C1.
Fig.
6. Output power scan of the solar cell array.
Fig.
7. Experimental results for the MPPT performance of the proposed solar power
generation system.
CONCLUSION:
This
paper proposes a solar power generation system to convert the dc energy
generated by a solar cell array into ac energy that is fed into the utility.
The proposed solar power generation system is composed of a dc–dc power
converter and a seven level inverter. The seven-level inverter contains only
six power electronic switches, which simplifies the circuit configuration. Furthermore,
only one power electronic switch is switched at high frequency at any time to
generate the seven-level output voltage. This reduces the switching power loss
and improves the power efficiency. The voltages of the two dc capacitors in the
proposed seven-level inverter are balanced automatically, so the control
circuit is simplified. Experimental results show that the proposed solar power
generation system generates a seven-level output voltage and outputs a
sinusoidal current that is in phase with the utility voltage, yielding a power
factor of unity. In addition, the proposed solar power generation system can
effectively trace the maximum power of solar cell array.
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[1]
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