ABSTRACT:
A new, hybrid integrated topology, fed by
photovoltaic (PV) and fuel cell (FC) sources and suitable for distributed generation
applications, is proposed. It works as an uninterruptible power source that is
able to feed a certain minimum amount of power into the grid under all
conditions. PV is used as the primary source of power operating near maximum
power point (MPP), with the FC section (block), acting as a current source,
feeding only the deficit power. The unique “integrated” approach obviates the
need for dedicated communication between the two sources for coordination and
eliminates the use of a separate, conventional dc/dc boost converter stage
required for PV power processing, resulting in a reduction of the number of
devices, components, and sensors. Presence of the FC source in parallel (with
the PV source) improves the quality of power fed into the grid by minimizing
the voltage dips in the PV output. Another desirable feature is that even a
small amount of PV power (e.g., during low insolation), can be fed into the
grid. On the other hand, excess power is diverted for auxiliary functions like
electrolysis, resulting in an optimal use of the energy sources. The other
advantages of the proposed system include low cost, compact structure, and high
reliability, which render the system suitable for modular assemblies and
“plug-n-play” type applications. All the analytical, simulation, and
experimental results of this research are presented.
KEYWORDS:
1.
Buck-boost
2.
Distributed
generation
3.
Fuel cell
4.
Grid-connected
5.
Hybrid
6.
Maximum power point tracking (MPPT)
7.
Photovoltaic
SOFTWARE:
MATLAB/SIMULINK
CONCLUSION:
A
compact topology, suitable for grid-connected applications has been proposed.
Its working principle, analysis, and design procedure have been presented. The
topology is fed by a hybrid combination of PV and FC sources. PV is the main
source, while FC serves as an auxiliary source to compensate for the uncertainties
of the PV source. The presence of FC source improves the quality of power (grid
current THD, grid voltage profile, etc.) fed into the grid and decreases the
time taken to reach the MPP. Table IV compares the system performance with and
without the FC block in the system. A good feature of the proposed
configuration is that the PV source is directly coupled with the inverter (and
not through a dedicated dc–dc converter) and the FC block acts as a current
source. Considering that the FC is not a stiff dc source, this facilitates PV
operation at MPP over a wide range of solar insolation, leading to an optimal
utilization of the energy sources. The efficiency of the proposed system in
mode-1 is higher (around 85% to 90%) than mode 2 and 3 (around 80% to 85%). A
laboratory prototype of the proposed system has shown encouraging results in
terms of efficiency, complexity, reliability, EMI concerns, and other features.
Table V compares the proposed system and some of the existing HDGS
configurations with respect to various parameters and features.
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[3]
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