OPTIMUM ALLOCATION OF DISTRIBUTED GENERATION BY LOAD FLOW ANALYSIS METHOD: A CASE STUDY

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IJRET: International Journal of Research in Engineering and Technology
eISSN: 2319-1163 | pISSN: 2321-7308
OPTIMUM ALLOCATION OF DISTRIBUTED GENERATION BY LOAD
FLOW ANALYSIS METHOD: A CASE STUDY
Wasim Nidgundi1, Dinesh Ballullaya2, Mohammad Yunus M Hakim3
1PG student, Department of Electrical & Electronics, SDM College of Engineering and Technology Dharwad, Karnataka,
India
2Professor, Department of Electrical & Electronics, SDM College of Engineering and Technology Dharwad, Karnataka,
India
3PG student, Department of Electrical & Electronics, SDM College of Engineering and Technology Dharwad, Karnataka,
India
Abstract
DG is nothing but a small scale generation element connected directly to the distribution network or near customer load center. DG
affects the flow of power and voltage conditions at customers and utility equipment. These impacts may manifest themselves either
positively or negatively depending on the distribution system operating characteristics and the DG characteristics. DG has a limited
size of 10MW or less especially when DG is used in a distribution network. DG is installed at the place where it becomes unfeasible to
build a central generation plant. DG is installed to improve the voltage profile as well as minimize losses. DG allocation is a crucial
factor. Optimum DG allocation provides a variety of benefits. But inappropriate DG allocation can cause low or over voltage in the
network. In this paper a case study is carried out for the Dharwad region, Karnataka. Load flow based method and ETAP software is
used to determine the optimum location & optimum size of DG for voltage profile improvement & loss reduction.
Keywords: Distributed Generation, Load flow Analysis, ETAP, optimum location, voltage profile improvement.
----------------------------------------------------------------------***----------------------------------------------------------------------
1. INTRODUCTION
The optimal placement and sizing of generation units on the
distribution network has been continuously studied in order to
Distributed generation is related to the use of small generation
achieve different aims. The objective can be the minimization
units installed in strategic points of the electric power system
of the active losses of the feeder [2], or the minimization of
and mainly, close to load centers. DG can be used in an
the total network supply costs, which includes generators
isolated way, supplying the consumer's local demand or in an
operation and losses compensation [3], [4],or even the best
integrated way, supplying energy to the remaining of the
utilization of the available generation capacity [5]. As a
electric system. In distribution systems, DG can provide
contribution to the methodology for DG allocation, in this
benefits for the consumers as well as for the utilities,
paper it is presented an algorithm for the allocation of
especially
in
sites
where
the
central
generation
is
generators in distribution networks, in order to voltage profile
impracticable
or
where
there
are
deficiencies
in
the
improvement and loss reduction in distribution network.
transmission system. A distributed power element can be
connected directly to a utility's transmission or distribution
This paper represents a novel approach to analyze the power
system or to consumer's terminal. Distributed generation is
system network by using ETAP with the help of one line
not centrally planned, today not centrally dispatched; it is
diagram. This diagram is implemented in ETAP to perform
usually connected to the distribution network & its size may
load flow study. The system is analyzed under steady state by
be smaller than 50 or 100MW [1].
using load flow analyses method; the data which is taken for
the case is peak load data.
DG must be reliable, transmittable of the proper size and
strategically placed to give the following system benefits: grid
Section 2 is the complete single line diagram of the system
reinforcement, voltage support and improved power quality,
under consideration; this diagram is implemented based upon
loss reductions, transmission and distribution capacity release,
practical data in ETAP for simulation purpose in Section 3
improved
utility
system
reliability,
congestion
control,
describes about load flow methodology. Section 4 and 5
Reduction in fuel and operating costs, Enhanced productivity,
consists of ETAP simulation techniques and algorithm for the
reduce reserve requirement, increase system security.
case study and contains analysis which include load flow.
Section 6 deals with Conclusion of this research work.
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2 SINGLE LINE DIAGRAM OF CASE UNDER
STUDY
Fig. 1 shows the single line diagram of the complete power
system of the Dharwad, Karnataka region which is under
study. It is clear from the Fig. 1 that there are two incoming
lines of 110 kV supplying power to seven substations and
these substations are connected with 11 kV power distribution
network (11 kV feeders).
The load connected with the system is industrial load, offices
load, plazas, shops and domestic load. The load can also be
classified as lights, fans, air conditioners, room coolers, water
coolers, printers, computers, induction motors, irrigation
pumps and the other industrial equipment etc. Comprehensive
Fig -2: Single line diagram of Belur Substation
load modelling is performed in ETAP based upon original
system data.
Monitoring Points are also marked on the same single line
diagram. The buses are named according to the substation
name. Different power transformers with ratings are shown in
the single line diagram to step down the voltage level. Single
line diagram of the different composite network is also shown
Fig -3: Single line diagram of KUD Substation
Fig -1: Single line diagram of Dharwad Area
Fig -4: Single line diagram of lakmanahalli Substation
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Fig -5: Single line diagram of Mrutyunjaya Substation
Fig -7: Single line diagram of Tadasinkoppa Substation
Fig -6: Single line diagram of Navnagar Substation
Fig -8: Single line diagram of Tarihal Substation
3. POWER FLOW ANALYSIS
Power flow analysis is one of the most common computational
procedures used in power system analysis. Power flow
calculation presents state of the system for a given load and
generation. These studies help to analyze the steady state
performance of the power system under various operating
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IJRET: International Journal of Research in Engineering and Technology
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conditions. They are used to determine the circuit loading,
Table -1: The voltage of the buses after load flow Before DG
voltages at the various buses, reactive power flow, system
installation
losses, and branch losses. The studies also helps to identify
critical conditions such as over voltages, under voltages,
Bus ID
Voltage
Bus ID
Voltage
operation near rated value etc. and desired transformer tap
(P.U)
(P.U)
settings. Power flow studies and analysis of the continuous
BELUR
process plant with CPP was performed to ensure the security
BUS-1
0.968845455
MR BUS-3
0.934363636
of the power system with respect to available generation
BELUR
capacity and voltage profiles at various buses for various
BUS-2
0.93830303
MR BUS-4
0.954393939
operating conditions.
BELUR
NAREND
BUS-3
0.921181818
RA BUS
0.969881818
4. SIMULATION TECHNIQUES
BELUR
NVNGR
BUS-4
0.921181818
BUS-1
0.970172727
The paper presents a method using load flow analysis to
allocate a DG at optimum place to improve the system voltage
BELUR
NVNGR
profile also another method to select the size of Discrete
BUS-5
0.921181818
BUS-2
0.944181818
Generation to maintain the a minimum loss and voltage profile
KUD
PGCL
BUS-1
0.968581818
BUS
1
4.1 Proposed Methodology
KUD
BUS-2
0.954636364
SRS BUS1
1
To find the proper DG allocation in a distribution system for
KUD
voltage profile improvement is the main aim of this procedure.
BUS-3
0.954636364
SRS BUS2
0.9746
The method is based on load flow. The sensitive buses to
LKH
TAD
voltage (the buses that have a low voltage scale) are
BUS-1
0.969190909
BUS1
0.970318182
considered and ranked in the first step, the aim of this step is
LKH
TAD
to install the DG unit for voltage control and the DG is placed
BUS-2
0.944090909
BUS2
0.951272727
in all buses & the voltage profile of the entire system in each
LKH
TRL
installation is considered in the second step. After DG
BUS-3
0.944090909
BUS-1
0.9746
installation in each bus, the voltage profiles of all states are
LKH
TRL
ranked from the best state to worst. Finally, two lists are
BUS-4
0.927454545
BUS-2
0.954909091
considered to choose the best place to install the DG
LKH
TRL
distribution system to provide a good voltage profile.
BUS-5
0.927454545
BUS-3
0.952848485
TRL
4.2 Computational Procedure
MR BUS-1
0.969372727
BUS-4
0.942272727

Run the base case load flow
MR BUS-2
0.934363636

The graph of voltage v/s bus ID is plotted

From the graph (voltage v/s Bus ID), the priority list is
1.02 VOLTAGE PROFILE BEFORE DG ALLOCATION
formed: the sensitive buses (that should have a voltage
1
V
control) in highest rank.
0.98
O

DG is placed in each bus
0.96
L

0.94
Run the load flow of the system after DG installation in
T
0.92
each bus.
A
0.9

Then the graphs of voltage profile of the system after
G
0.88
placement of DG in each bus is drawn.
E
(
1 2 3 4 5 1- 2- 3- 1 2 3 4 5 1 2 3 4 S 1 2 S 1 2
1 2 3 4

S1 S2
Then another priority list is formed in this format: after
S- S- S- S- S-
S- S- S- S- S- S- S- S- S-
P
BU S- S-
S- S- S- S-
BU BUS BUS BU BU
comparing the graphs, it is required to rank them from
.
BU BU BU BU BU BUS BUS BUS BU BU BU BU BU BU BU BU BU
BU BU
BU BU BU BU
R R D D D
R R CL
the best profile to the worst one.
DRA
AD AD RL RL RL RL
U
)
LUR LUR LUR LU LU
LKH LKH LKH LKH LKH MR MR MR MR N G G PG SRS SRS T T T T T T

KU KU KU
The proper place of DG is chosen by comparing the
E E
BE BE BE B B
VN VN
priority list of Simulation Results i.e. the Bus ID's with
ARE N N
N
the highest ranking
: The load flow is done on the
distribution system and the voltages are shown in table
1.
Fig -9: The voltage profile of the system before DG allocation
Now according to the algorithm, the buses should be ranked
from the minimum value of the voltage to the maximum one.
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Table -2: The buses are ranked from minimum value to
Table -4: The buses are ranked from best voltage profile to
maximum value (before DG installation)
worst voltage profile after DG installation.
Voltage
Bus ID
Voltage(P.U)
Rank
Bus ID
P.U
Rank
LKH
BUS-1,NVNGR
BUS-
BELUR BUS-3,BELUR BUS-4,
1,KUD BUS-1,SRS BUS2,TRL
BELUR
BUS-5,LKH
BUS-
BUS-1,TAD BUS1,MR BUS-
4,LKH BUS-5
0.92-0.93
1
1,NARENDRA BUS
1.0002-1.0051
1
MR BUS-2,MR BUS-3,BELUR
BUS-2
0.93-0.94
2
BELUR BUS-1,BELUR BUS-
TRL BUS-4,LKH BUS-2,LKH
3,BELUR
BUS-4,BELUR
BUS-3, NVNGR BUS-2
0.94-0.95
3
BUS-5,KUD
BUS-2,KUD
TAD
BUS2,TRL
BUS-3,MR
BUS-3,LKH
BUS-2,LKH
BUS-4, KUD BUS-2,KUD BUS-
BUS-3,LKH
BUS-4,LKH
3,TRL BUS-2
0.95-0.96
4
BUS-5,MR BUS-2,MR BUS-
KUD
BUS-1,BELUR
BUS-
3,MR BUS-4,NVNGR BUS-
1,LKH
BUS-1,MR
BUS-
2,PGCL BUS,SRS BUS1,TAD
1,NARENDRA BUS
0.96-0.97
5
BUS2,TRL BUS-2,TRL BUS-
0.9951-
NVNGR BUS-1,TAD BUS1,SRS
3,TRL BUS-4.
1.00000
2
BUS2,TRL BUS-1
0.97-0.98
6
BELUR BUS-2
0.9902-0.9951
3
----------
0.98-0.99
7
PGCL BUS,SRS BUS1
0.99-1.0
8
Comparing table 2 & 4, it is necessary to rank the best buses
for DG installation.
The voltage profile of each state is found after DG installation
on each bus. The voltage profiles are ranked from the best
Table 5 shows the best locations for 7.5 MW DG installation
profile to worst one. Table 4 shows the ranking of voltage
to improve the voltage profile and voltage stability. The
profile of buses after DG installation.
important point that can be already considered from the table
V is that the optimum DG locations are the bus ID BELUR
Table -3: The voltage of the buses after load flow after dg
BUS-3, LKH BUS-4 and MR BUS-2. The other ranking in the
allocation at all buses.
table are not very important because it is not necessary to
locate the best place. The voltage profiles of the distribution
Bus ID
Voltage
Bus ID
Voltage
system in the presence of DG in buses BELUR BUS-3, LKH
(P.U)
(P.U)
BUS-4 and MR BUS-2 are shown below. It shows the voltage
BELUR
profile improvement.
BUS-1
1
MR BUS-3
1
BELUR
Table -5: Optimum bus ID's for dg allocation
BUS-2
0.994333
MR BUS-4
1
BELUR
NARENDRA
BUS ID
RANK
BUS-3
1
BUS
1.0001
BELUR BUS-3,LKH BUS-4
1
BELUR
NVNGR
MR BUS-2
2
BUS-4
1
BUS-1
1.004
BELUR
NVNGR
BELUR BUS-2
3
BUS-5
1
BUS-2
1
TRL BUS-4,LKH BUS-2,NVNGR BUS-2
4
KUD BUS-1
1.002591
PGCL BUS
1
TAD
BUS2,TRL
BUS-3,MR
BUS-4,KUD
5
KUD BUS-2
1
SRS BUS1
1
BUS-2,
KUD BUS-3
1
SRS BUS2
1.000745
KUD BUS-3,TRL BUS-2
LKH BUS-1
1.005091
TAD BUS1
1.0002
KUD
BUS-1,LKH
BUS-1,MR
BUS-1,
6
LKH BUS-2
1
TAD BUS2
1
NARENDRA BUS
LKH BUS-3
1
TRL BUS-1
1.000745
BELUR BUS-1
7
LKH BUS-4
1
TRL BUS-2
1
NVNGR BUS-1,TAD BUS1,SRS BUS2,TRL
8
LKH BUS-5
1
TRL BUS-3
1
BUS-1
MR BUS-1
1.000164
TRL BUS-4
1
PGCL BUS,SRS BUS1
9
MR BUS-2
1
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IJRET: International Journal of Research in Engineering and Technology
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Table -6: voltage profile display after 7.5MW DG installation
interconnected at transmission voltage where the system is
at 3 buses (MR BUS-2, BELUR BUS-3, and LKH BUS-4)
designed to accommodate many generators.
Bus ID
Voltage
Bus ID
Voltage
5.1 Proposed Methodology
(P.U)
(P.U)
To find the optimum size of a DG unit in order to decrease the
BELUR
power loss as well as to maintain a good voltage profile of the
BUS-1
0.9805
MR BUS-3
0.971545455
distribution system is the aim of this procedure. To determine
BELUR
the optimum size it is necessary to install different sizes of
BUS-2
0.950212121
MR BUS-4
0.966151515
DGs at optimum place (the place where total system loss is
BELUR
NARENDR
minimum)
BUS-3
0.951
A BUS
0.981290909
BELUR
NVNGR
5.2 Computational Procedure
BUS-4
0.951
BUS-1
0.982063636
BELUR
NVNGR
After determining optimum DG location for voltage profile
BUS-5
0.951
BUS-2
0.956272727
improvement, the following steps are followed for finding
KUD
optimum DG size.
BUS-1
0.980681818
PGCL BUS
1

In this procedure different size of DG is placed at the
KUD
optimum location (i.e. at MR BUS-2, BELUR BUS-3,
BUS-2
0.967363636
SRS BUS1
1
and LKH BUS-4 of the power system).
KUD

It is also necessary to study the voltage profile& total
BUS-3
0.967363636
SRS BUS2
0.984036364
loss of the system after installing DG of different size.
LKH

The DG which provides a good voltage range with a
BUS-1
0.981890909
TAD BUS1
0.9815
minimum total power loss, acceptable as an optimum
LKH
size.
BUS-2
0.957030303
TAD BUS2
0.962636364
LKH
TRL
Table -7: Comparison of voltage & total loss for different dg
BUS-3
0.957030303
BUS-1
0.984036364
size at 3 buses (MR BUS-2, BELUR BUS-3, and LKH BUS-
LKH
TRL
4)
BUS-4
0.966363636
BUS-2
0.964545455
LKH
TRL
Voltage
BUS-5
0.966363636
BUS-3
0.962424242
DG size
Total losses
within limits
MR
TRL
MW
MW
MVAR
BUS-1
0.981009091
BUS-4
0.951909091
1
0.82
12.149
No
MR
BUS-2
0.971545455
2
0.776
11.381
No
3
0.734
10.652
No
4
0.703
10.074
No
1.02
V
1
Voltage Profile after DG
5
0.659
9.307
No
e
0.98
o (
0.96
allocation
6
0.624
8.691
Yes
l
P
0.94
0.92
7
0.592
8.113
Yes
t
.
... ... ... ... ...
... ... ...
R 1- 2- 3- 1 2 3 4 5 1 2 3 4 D R R S 1 2
1 2 3 4
N
G
S1 S2 S- S- S- S-
8
0.562
7.571
Yes
a U
LUR LUR LUR LUR LU
S- S- S- S- S- S- S- S- S-
)
E
BU
BE BE BE BE B BUS BUS BUS BU BU BU BU BU BU BU BU BU
VNG VN
BUS BUS BU BU BU BU BU BU
9
0.535
7.066
Yes
g
D D D
ARE
CL
N N N
SRS SRS AD AD RL RL RL RL
KU KU KU LKH LKH LKH LKH LKH MR MR MR MR
PG
T T T T T T
The marginal under voltage range is 0.95-0.98 P.U, bus
voltage below this range is known as critical under voltage.
Fig -10: The voltage profile of the system after DG allocation
The power system under study has a total loss of 0.958 MW &
at 3 buses
a voltage range of 0.923-1.0 P.U without DG. Bus voltage of
0.923 P.U is below the lower limit of marginal under voltage,
5. OPTIMUM DG SIZING
called critical under voltage. So the voltage profile (0.923-1.0
P.U) of power system under study without DG provides a
The size of DG depends upon the type of the load, power
worse voltage profile & the total loss of the system is high. It
quality and secondary distribution system, for these reasons
is necessary to install DG of optimum size at optimum
the size of DG which is considered is less than 10MW.
location to improve the voltage profile as well as to minimize
Distributed
generator
larger
than
this
is
typically
loss. The optimum size of DG is 7MW for the power system
__________________________________________________________________________________________________
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IJRET: International Journal of Research in Engineering and Technology
eISSN: 2319-1163 | pISSN: 2321-7308
under study, it is concluded after studying the table VII. The
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voltage profile for DG with 7MW capacity is shown below.
[1]
F.Gonzalez-Longatt,C.Fortoul
" Review Of The
Distributed
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1.02
Voltage profile for 7MW DG
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K.
Nara,
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0.98
o e
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l
P
0.94
2001IEEE Power Engineering Society Winter Meeting,
0.92
t
.
... ... ... ... ...
... ... ...
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1- 2- 3- 1 2 3 4 5 1 2 3 4 R R S 1 2
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S1 S2 S- S- S- S-
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N
BU
g
BE BE BE BE BE BUS BUS BUS BU BU BU BU BU BU BU BU BU
VN VN
BUS BUS BU BU BU BU BU BU
allocation in MV distribution networks," in Proc.2001
D D D
CL
ARE N N
SRS SRS AD AD RL RL RL RL
IEEE PICA Conference, pp. 81-86.
KU KU KU LKH LKH LKH LKH LKH MR MR MR MR N
PG
T T T T T T
[4]
W. El-Khattam, K. Bhattacharya, Y. Hegazy, and M.
M. A. Salama, "Optimal investment planning for
Fig -11: The voltage profile of the system after DG allocation
distributed generation in a competitive electricity
at 3 places with 7MW capacity.
market," IEEE Trans. Power Systems, vol. 19, pp.
1674-1684, Aug.2004.
[5]
A. Keane, and M. O'Malley, "Optimal allocation of
6. CONCLUSIONS
embedded generation on distribution networks," IEEE
The size & location of DGs are crucial factors in the
Trans. Power Systems, vol. 20, pp. 1640-1646, Aug.
application
of
DG
for
loss
minimization
&
voltage
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improvement respectively. This paper deals with a load flow
[6]
B.Kuri, M.Redfern, F.LI, " Optimization of rating and
based simulation using ETAP to find out the optimum location
positioning of dispersed generation with minimum
& optimum size of DG unit for voltage profile improvement &
network disruption",2004 IEEE power engineering
minimizing power losses in the Power System Under study.
society general meeting, 6-10 June 2004, vol. 2,pp.
The installation of DG unit at non optimal places can result in
2074-2078.
an increase in system losses; implying in an increase in costs
[7]
Nibedita
Ghosh,
Sharmistha
Sharma,
Subhadeep
& resulting low or over voltages in the network, having an
Bhattacharjee "A Load Flow based Approach for
effect opposite to the desired. For that reason, the use of a
Optimum Allocation of Distributed Generation Units in
methodology capable of analyzing the influence on some
the Distribution Network for Voltage Improvement and
system characteristics of DG allocation can be very useful for
Loss
Minimization",
International
Journal
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the system planning engineer when dealing with the increase
Computer Applications (0975 - 8887) Volume 50 -
of DG penetration that is happening nowadays. The proposed
No.15, July 2012
algorithm is already discussed in this paper, more accurate &
[8]
A.Cano, F.Jurado, " Optimum location of biomass-
can identify the best location for single DG placement in order
fuelled gas turbines in an electric systems",2006 IEEE
to improve the voltage profile & to minimize total power
power Engineering Society General Meeting, 18-22
losses. The proposed method has also used to determine the
June 2006.
optimum size & location of DG unit. Results prove that the
optimum size & location of a DG can save a huge amount of
BIOGRAPHIES
power.
Power
system
deregulation
and
shortage
of
transmission capacities have led to an increase interest in
Wasim Nidgundi Currently pursuing M.Tech in
Distributed generations (DGs) sources. The optimal location
Power
system
Engineering
at
SDMCET
of DGs in power systems is very important for obtaining their
Dharwad.
Obtained
B.E
from
SDMCET
maximum potential benefits. In this paper, only optimum
Dharwad.Area of interest are power system
location of DG has been determined for loss reduction and
planning, power system reliability studies, real
voltage improvement in the distribution system. For proper
time power system studies.
allocation of DG, size of DG also plays an important role. Size
of DG effects losses and voltage profile of the distribution
Prof.Dinesh Ballullaya currently working as a
system. Also a comparative study can be done between
professor in SDMCET Dharwad. Obtained his
different techniques like Analytical method, Optimum power
B.E and M.Tech from SJCE mysore.He has 31
flow
method,
Evolutionary
techniques
like
Genetic
years of experience in teaching. Areas of
Algorithm(GA), Fuzzy logic etc. for finding optimum size and
Expertise Electrical machines.
location
of
DG
for
loss
minimization
and
voltage
improvement of the power system.
__________________________________________________________________________________________________
Volume: 03 Issue: 05 | May-2014, Available @ http://www.ijret.org
294

IJRET: International Journal of Research in Engineering and Technology
eISSN: 2319-1163 | pISSN: 2321-7308
Mohammad
Yunus
M
Hakim
Currently
pursuing M.Tech in Power system Engineering
at SDMCET Dharwad. Obtained B.E from
BLDE bijapur.Area of interest is power quality
study, electrical machines.
__________________________________________________________________________________________________
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