ABSTRACT:
In this work, a simple
phase-locked loop – less control is presented for a single-stage solar
photovoltaic (PV) – battery-grid-tied system. As compared to traditional solar
PV systems, the system has reduced losses due to the absence of boost converter
and a flexible power flow due to the inclusion of a storage source (battery). The
synchronous reference frame theory is used to generate the pulses for switching
the voltage-source converter (VSC), while maximum power is extracted from the
solar PV array by using perturb and observe-based maximum power point tracking
technique. The inherent feature of shunt active filtering by the VSC has also
been incorporated in this system. Test results for the system operation under
fixed power and variable power mode are studied on a prototype developed in the
laboratory. During fixed power mode, a fixed amount of power is fed to the
grid, whereas in variable power mode the power fed to the grid varies. Test
results obtained are in accordance with the IEEE-519 standard. This work is a
basis for the upcoming power market, where solar PV consumers can manage the
generated electricity and maximise their profit by selling the power to the
grid judiciously.
SOFTWARE: MATLAB/SIMULINK
Fig.1 Proposed topology
EXPERIMENTAL RESULTS:
Fig. 2 Performance of the system at steady state under fixed power mode
(b) vgab,
iga, ila and iaspv, (c) Vdc, Ipv, Vbat and Ibat
Fig. 3 Impact of a decrease in load
and insolation level during fixed power mode
(a)
vgab, iga, ila and iaspv,
(b) Vdc, Ipv, Vbat and Ibat. Impact of a decrease
in solar insolation during fixed power mode (c) vgab, iga,
Ipv and iaspv, (d) Vdc, Ipv, Vbat and Ibat
Fig. 4 Impact of increase in solar
insolation during fixed power mode
(a)
vgab, iga, Ipv and iaspv, (b) Vdc, Ipv,
Vbat and Ibat. Performance of the system at steady state under variable power
mode
Fig. 5 Performance of the system at
steady state under variable power mode
(d) Grid power
Fig. 6 Impact of load unbalancing and
solar variations on solar PV-battery-grid-tied system
(a)
vgab, igc, ilc and icspv, (b) Vdc,
Ipv, Vbat and Ibat. Impact of solar variation on solar PV-battery-grid-tied
system (c) vgab, iga, ila and Ipv, (d) Vpv, Vbat, Ibat and iaspv
Fig. 7 Impact of solar variation and battery
disconnection on solar PV-battery-grid-tied system
(c)
vgab, iga, ila and iaspv, (d) Vdc, Ipv, Vbat
and Ibat
CONCLUSION:
A solar
PV-battery-grid-tied system has been implemented in this work. P&O-based
MPPT technique has been used to extract maximum power from the solar PV array,
while SRF theory has been used to control the VSC. No PLL has been used here,
the grid voltage vector angle with the α-axis, has been utilised to
obtain the reference grid currents. The system's operation under fixed power mode
is analysed, wherein a fixed amount of power is fed to the grid irrespective of
the insolation and load variation. The battery gets charged/discharged in order
to adjust these variations. Moreover, during the variable power mode, under
load disconnection and solar insolation increase, the power fed to the grid
increases. Even if the battery gets disconnected, the power generated by the
solar PV array is fed to the grid and the load without any issue. Moreover, all
these test results obtained are in accordance to an IEEE-519 standard.
REFERENCES:
[1] Esram, T., Chapman, P.L.: ‘Comparison
of photovoltaic array maximum power point tracking techniques,’ IEEE Trans.
Energy Convers., 2007, 22, (2), pp. 439–449
[2] Deshpande, A., Patil, S.L., Deopare,
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methods’. Proc. Int. Conf. Computing, Communication and Automation (ICCCA),
2016, pp. 1025–1028
[3] Sahu, H.S., Nayak, S.K.: ‘Numerical
approach to estimate the maximum power point of a photovoltaic array,’ IET Gener.
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[4] Libo, W., Zhengming, Z., Jianzheng,
L.: ‘A single-stage three-phase grid connected
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compensation,’ IEEE Trans. Energy Convers., 2007, 22, (4), pp. 881– 886
[5] Jain, S., Agarwal, V.: ‘A
single-stage grid connected inverter topology for solar PV systems with maximum
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