ABSTRACT:
This paper introduces a residential photovoltaic
(PV) energy storage system, in which the PV power is controlled by a dc–dc converter
and transferred to a small battery energy storage system (BESS). For managing
the power, a pattern of daily operation considering the load characteristic of
the homeowner, the generation characteristic of the PV power, and the power leveling
demand of the utility is prescribed. The system looks up the pattern to select
the operation mode, so that powers from the PV array, the batteries, and the
utility are utilized in a cost-effective manner. As for the control of the
system, a novel control technique for the maximum power-point tracking (MPPT)
of the PV array is proposed, in which the state-averaged model of the dc–dc
converter, including the dynamic model of the PV array, is derived.
Accordingly, a high-performance discrete MPPT controller that tracks the
maximum power point with zero-slope regulation and current-mode control is
presented. With proposed arrangements on the control of the BESS and the current-to-power
scaling factor setting, the dc–dc converter is capable of combining with the
BESS for performing the functions of power conditioning and active power
filtering. An experimental 600-W system is implemented, and some simulation and
experimental results are provided to demonstrate the effectiveness of the
proposed system.
KEYWORDS:
1.
Active power
filtering
2.
Battery energy storage system
3.
Maximum power-point tracking
4.
Power conditioning
SOFTWARE: MATLAB/SIMULINK
CIRCUIT DIAGRAM:
Fig.
1. The power circuit of proposed PV energy storage system.
EXPECTED SIMULATION RESULTS:
Fig.
2. Simulated results of MPPT control. (a) An increasing step change in Ip.
(b) A decreasing step change in Ip.
Fig.
3. Measured waveforms of 
, and
in MPPT control.
, andin MPPT control.
Fig.
4. System operations. (a) Measured waveforms when system is changed from mode 3
to mode 2, where subscripts o;L; and u are used to represent the BESS, the
load, and the utility, respectively. (b) Measured real power waveforms in
various operation modes.
CONCLUSION:
This
paper has proposed a residential PV energy storage system, where the PV power
is controlled by a dc–dc converter and transferred to a small BESS. The
proposed system, possessing the functions of power conditioner and active power
filter, is capable of providing an optimal interface with the utility. The
additional PV power makes the system flexible in power usage, so that all
powers in the system can be utilized in a cost-effective manner. Some control
techniques for realizing the functions of the proposed system, including the
MPPT control of the PV array and control of power flows in the system, have
been presented. A prototype 600-W system was implemented, and some simulated
and experimental results were provided to demonstrate the effectiveness of the
proposed system. Although the setup cost of the proposed system is high, such
that it is hard to compete with the current utility power, we believe that the
capital issue will be resolved if there is a political encouragement in the
kilowatt price and the market is large enough.
REFERENCES:
[1]
G. J. Jones, “The design of photovoltaic systems for residential applications,”
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[2]
G. L. Campen, “An analysis of the harmonics and power factor effects at a
utility intertied photovoltaic system,” IEEE Trans. Power App. Syst., vol.
PAS-101, pp. 4632–4639, Dec. 1982.
[3]
C. M. Liaw, T. H. Chen, S. J. Chiang, C. M. Lee, and C. T. Wang, “Small battery
energy storage system,” Proc. Inst. Elect. Eng., vol. 140, pt. B, no. 1,
pp. 7–17, 1993.
[4]
S. J. Chiang, “Design and implementation of multi-functional battery energy
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University, Hsin-Chu, Taiwan, R.O.C., 1994.
[5]
Z. Salameh and D. Taylor, “Step-up maximum power point tracker for photovoltaic
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