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SSRG International Journal of Electrical and Electronics Engineering (SSRG-IJEEE) – volume 1 Issue 9 –November 2014
Design and Analysis of Fuzzy Logic Control Current Source
Inverter for Grid Connected PV System.
Y.Santhosh *1, Kurva Mallikarjuna*2,
M-Tech Student Department of EEE, VBIT, Aushapur, Ghatkesar, R.R (Dt), Telangana, India.
Assistant Professor, Department of EEE, VBIT, Aushapur, Ghatkesar, R.R (Dt), Telangana, India.
ABSTRACT
The SVPWM based voltage source inverter topology
is used for grid interfacing of DG system to employ a
power conditioning photovoltaic unit is normally
required to another photo electric converter stage.
The current source inverter offers many advantages
over VSI in terms of boosting and short circuiting
protection capabilities including the direct current
controllability and ac-side simpler filter structure.
The research on SVPWM based DG is still
development state where this paper focus on
modeling and controlling and steady state transient
performance of a PV system based on CSI by
performing a comparative performance analysis of
VSI and CSI based PV system under transient fault
conditions are verified using MATLAB/Simulink
software based on detailed system model.
Key Words: Control, Photovoltaic, SVPWM, CSI.
I.
INTRODUCTION
In recent past years the photovoltaic (PV)
systems have been received unprecedented
concentration due to the raise of concerns about
adverse effects of extensive use of fossil fuels on the
environment and energy utilization with security in
grid-connected PV systems that are still outnumbered
by the power generation schemes which are based on
oil or natural gas or coal or nuclear or hydro or wind
or any combination of these [1] PV systems capacity
is majorly based on the order of tens of megawatts
that have been installed and interfaced at the grid
level in the primary distribution where the PV system
installation at the secondary distribution level are
dominated by rooftop units with distinct capacities on
the order of a few kilowatts with no significant
impact on the existing power systems. Due to the
growing interest in the usage of solar energy and
adoption of national policies in favor of green energy
where the emphasis is on significant increase in the
number of large size PV plants which shows
significant impact on the existing power grids that are
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expected as the two main components of a PV system
which encompasses PV modules and power
electronic inverters where the PV modules contribute
to the overall cost of PV systems in a big way.
A downward trend is clearly identified in the price
per watt of PV modules due to substantial increase in
the production of PV modules in different parts of the
world the price of a PV module was USD per watt
and the current market price is USD per watt where
the practice in PV inverter mainly relies on voltagesource inverter (VSI) topology that normally requires
another stage of power-electronic conversion for
stepping up the voltage of the PV modules for a
large-scale PV inverter which reduces the cost and
improves the robustness and performance of powerelectronic grid interface which can further facilitate
proliferation of PV systems in power systems. The
current-source inverter (CSI) has the capability of
becoming the most preferred topology for interfacing
the PV system for the ac power grid due to following
reasons.
1) The CSI provides a smooth dc-side current which
is the most desirable feature of any PV module.
2) The energy storage element of a CSI has a larger
lifetime than that of a VSI in implementation.
3) The CSI has an inherent voltage boosting
capability that allows the integration of PV panels of
lower output voltages and diminishes the
requirements of the step-up interface transformer.
4) With the evolution of reverse-blocking (RB) in
IGBT switches the series diodes will be eliminated
due to which a justifiable reduction in the cost and
conduction losses.
5) The recent advancements in super conductor
technology leads us to the development of
superconducting magnetic energy storage (SMES)
systems that can considerably reduce the losses in the
energy storage element of the CSI.
II.
RELATED WORK
The diagram of the proposed three-phase with
single stage grid connected PV system along with a
CSI as the power conditioning unit is illustrated in
Fig.1where the PV array is a parallel combination of
np PV modules while each PV module is a series of
combination of ns PV cells and the dc side inductor
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SSRG International Journal of Electrical and Electronics Engineering (SSRG-IJEEE) – volume 1 Issue 9 –November 2014
Ldc filters out the ripples in the dc side current and
allows its control where as the ac side of the inverter
is interfaced with the primary side of the transformer
Tr through a capacitive filter comprises of three Yconnected capacitors Cf which are tend to absorb the
switching harmonics and to produce a clean
sinusoidal current at the grid interface by including a
breaker Bpv which is an integral part of the PV
system and is provided to protect the PV system by
isolating it when there is fault on the secondary side
of the transformer Tr and the primary side of the
transformer is delta connected whereas its secondary
side is star connected with a solidly grounded neutral
point where the resistance and inductance of the
distribution line which is represented by Rg and Lg
respectively Ps and Qs respectively represents the
active and reactive powers that are supplied by the
PV system to the distribution system where the
breaker is part of the protection system installed by
the utility. The control structure of the proposed
solution for the CSI based PV system comprises of an
outer current control loop that is designed to control
the dc-side current and an inner current control loop
which is responsible for controlling the current that is
injected into the grid with a maximum power point
tracker (MPPT) is installed to ensure that the PV
array is operating at its maximum power range.
Current input type PV module where in this paper we
implemented the Current input type PV module in
simulink for single PV module which is shown in
below figure 6.
Figure 6 Single PV Module implemented in
Simulink
Dlg
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Figure 1 proposed three-phase single-stage grid
connected PV system based on CSI.
The PV array is connected to a distribution network
with a voltage source converter (VSC) to analysis
and control conveniently dq components in d-and-qaxis that are presented.
III.
SIMULATION RESULTS
Simulation of PV System
In the below figure 7 the PV array consists of six PV
modules that are connected in series altogether by
generating 133V dc voltage where the module can be
implemented as voltage input type PV module or
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SSRG International Journal of Electrical and Electronics Engineering (SSRG-IJEEE) – volume 1 Issue 9 –November 2014
Slg fault
Vabpcc
Tpg fault
Vabcpcc
Idc
Idc
Iabcs
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Iabccsi
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SSRG International Journal of Electrical and Electronics Engineering (SSRG-IJEEE) – volume 1 Issue 9 –November 2014
Iabcpcc
Iabccsi
Ll fault
Vabcpcc
Iabcpcc
Idc
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Pv64 fuzzy
Isolation
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SSRG International Journal of Electrical and Electronics Engineering (SSRG-IJEEE) – volume 1 Issue 9 –November 2014
Vabcpcc
Iabcs
Idc
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Vabc,iabc
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SSRG International Journal of Electrical and Electronics Engineering (SSRG-IJEEE) – volume 1 Issue 9 –November 2014
REFERENCES
[1] M.Ciobotaru, T.Kerekes ,R.Teodorescu, A. Bouscayrol, “PV
inverter simulation using MATLAB/Simulink graphical
environment and PLECS blockset,” IEEE IECON 2006 Annual
Conference on Industrial Electronics, pp. 5313-5318, Nov. 2006.
[2] S. Oh, M. Sunwoo, “Variable structure PWM controller for
high efficient PV inverters,” IEEE International Conference on
Sustainable Energy Technologies, pp. 24-27, Nov. 2008.
[3] J. P. Benner and L. Kazmerski, “Photovoltaics gaining greater
visibility,” IEEE Spectr., vol. 36, no. 9, pp. 34–42, Sep. 1999.
[4] Trends in Photovoltaic Application, Survey Report of Selected
IEA Countries Between 1992 and 2002
International Energy Agency Photovoltaic Power System, IEA,
Pvps t1-12:2003, 2003 [Online]. Available: www.iea-pvps.org
[5] S.K. Chung, “A phase tracking system for three phase utility
interface inverters,” IEEE Trans. Power Electron., vol. 15, no. 3,
pp. 431–438, May 2000.
[6] P.Vas, Vector Control of AC Machines. Oxford, U.K.: Oxford
Univ.Press, 1990.
Control ckt
IV.
CONCLUSION
In this paper we proposed a system which is based on
the grid connected PV system using MATLAB
software where the maximum power point tracking
(MPPT) and fault analysis are studied thoroughly
where the control consists of a current control
strategy that permits dc-link voltage regulation and
enables power factor control and a voltage control
strategy which significantly decouples dynamics of
the PV system from those of the distribution network
and loads and renders the PV system protected
against the external faults and the other one is voltage
control strategy which is capable of achieving the
maximum power point tracking and maximization of
the real power output of the PV system.
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