ABSTRACT:
This study presents a new circuit topology of the Modular
Multilevel Converter (MMC) which is deployed for photovoltaic grid
applications. In the conventional MMC, two arm inductors are placed in each
phase to limit the circulating current. In the proposed topology, the inductors
are replaced by a transformer. The proposed circuit gives a 50% reduction of
the voltage rating of the power devices and the capacitors in comparison with
the conventional MMC. The required dc-link voltage which is fed directly by PV
panels is also reduced by half. The paper presents a PWM method to control the
solar inverter output voltage. The proposed concept is confirmed through simulation
and experimental results.
KEYWORDS:
1. Photovoltaic (PV)
conversion
2. Modular multilevel
converter
3. Pulse width
modulation
4. Parameter
SOFTWARE:
MATLAB/SIMULINK
CONCLUSION:
In
this paper, the feasibility of a new circuit topology for the MMC has been
outlined, where it is deployed as an interface between the grid and PV modules.
With this arrangement, the voltage rating of capacitors and the power
semiconductor devices are effectively reduced by half. The dc bus magnitude which
is formed by the dc output from PV array is also reduced by half. A method to
suppress the 2nd harmonic current in the inverter has been discussed. The
concept of level-shifted PWM, where the modulating waveform is shifted and
scaled to bring inside one carrier, has been used to reduce the switching
frequency. With this, there is no need to calculate the duty cycle of
individual cells. The proposed idea has been verified by simulation and
experimental results under disturbance in the system caused by solar irradiance
changes.
REFERENCES:
[1]
Q.-C. Zhong and T. Hornik, Control of Power Inverters in Renewable Energy
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[2]
A. G. Golnas, “PV system reliability: An operator’s perspective,” IEEE J.
Photovolt., Vol. 3, No. 1, pp. 416-421, Jan. 2013.
[3]
International Energy Agency. (2010, May). Technology Roadmap, Solar
Photovoltaic Energy [Online].
[4]
E. Romero-Cadaval, G. Spagnuolo, L. G. Franquelo, et al., “Grid-Connected
Photovoltaic Generation Plants,” IEEE Ind. Electron. Mag., Vol. 7, No.
3, pp. 6-20, Sept. 2013.
[5]
M. G. Villalva, J. R. Gazoli and E. R. Filho, “Comprehensive Approach to
Modeling and Simulation of Photovoltaic Arrays,” IEEE Trans. Power Electron,
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