ABSTRACT:
With
the increase in the level of solar energy integration into the power grid,
there arises a need for highly efficient multilevel transformerless grid
connected inverter which is able to inject more power into the grid. In this
paper, a novel 5-level Hybrid Neutral Point Clamped transformerless inverter topology is proposed which has no
inherent ground leakage current. The proposed inverter is analyzed in detail
and its switching pattern to generate multilevel output is discussed. The
proposed inverter is compared with some popular transformerless inverter
topologies. Simulations and experiments results confirm the feasibility and
good performance of the proposed inverter.
SOFTWARE: MATLAB/SIMULINK
Fig.
1. Proposed hybrid neutral point clamped inverter
EXPECTED SIMULATION RESULTS:
Fig.
2. Inverter operation at UPF
Fig.
3. Inverter operation at 300 lag PF
Fig.
4. Inverter output for increase of modulation index from 0.45 to 0.95
Fig.
5. Inverter output for decrease of modulation index from 0.95 to 0.45
Fig.
6. Dynamic performance of inverter for increase of load
Fig.
7. Dynamic performance of inverter for decrease of load
Fig.
8. Inverter operation with chopper balancing circuit activated
Fig.
9. Inverter operation with chopper balancing circuit deactivated
CONCLUSION:
A
5-level Hybrid neutral point clamped transformerless PV grid connected inverter
is presented in this paper. The main characteristics of proposed
transformerless inverter are:
1)
Lower stress on the grid interfacing inductor, thereby reducing the filtering
cost and size as compared to conventional 3-level inverters like H5 and HERIC inverter.
2)
Lower cost as compared to 5L-DCMLI as the proposed inverter requires less no of
clamping diodes.
3)
Higher power handling capability as compared to conventional 3-level inverters.
4)
Higher efficiency as compared to 5L-DCMLI and H5 inverter.
5)
No common mode leakage current as the proposed inverter belongs to the family
of half bridge inverters.
6)
The proposed inverter is capable of exchanging reactive power with the grid.
Therefore,
with excellent performance in eliminating the CM current, multilevel output
voltage and high efficiency, the proposed inverter provides an exciting
alternative to the conventional transformerless grid-connected PV inverters. Moreover, due to its
superiority over the 5L-DCMLI in terms of efficiency and cost parameters, the
pertinence of the proposed inverter is not limited to grid connected PV inverters
and it can find its way for all the applications where currently 5L-DCMLI are
employed.
REFERENCES:
[1]
M. Calais and V. G. Agelidis,“Multilevel converters for single-phase grid
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[3]
E. Gubia, P. Sanchis, A. Ursua, J. Lopez, and L. Marroyo, “Ground currents in
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[4]
H. Xiao and S. Xie, “Leakage current analytical model and application in
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[5]
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