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8/9/2019 Reconfiguration and Load Balancing By Software Simulation In A Real Distribution Network for Loss Reduction
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Canadian Journal on Electrical and Electronics Engineering Vol. 2, No. 8, August 2011
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Reconfiguration and Load Balancing By Software
Simulation In A Real Distribution Network for Loss
ReductionH. Bagheri Tolabi , M. Gandomkar and M. Bahreyni Borujeni.
Abstract — To get the distribution network to operate at its
minimum loss optimum performance, reconfiguration was
been proposed and researched. Considering, however, that
optimum performance implies minimum loss, no overloading
of transformers and cables, correct voltage profile, and
absence of phase voltage and current imbalances, network
reconfiguration alone is insufficient. It has to be
complemented with techniques for phase rearrangement
between the distribution transformer banks and the specific
primary feeder with a radial structure and dynamic phase andload balancing along a feeder with a radial structure. This
paper contributes such a technique at the medium-voltage
level of a distribution network with reconfiguration. This
paper introduces a CYMEDIST based analysis for the phase
balancing/loss minimization problem. An application example
of the proposed analysis has been applied to Khorramabad
city's MV distribution network.
Key Words — load balancing, power loss, reconfiguration, MV
distribution system.
I. INTRODUCTION
studies show that a considerable part of the losses in powersystems is related to the electricity distribution network . There
are several ways to reduce losses in distribution system . Many
of methods need the new equipment installed within the system
in addition to the financial burden for companies, it is possible
new errors produce in network and due to disturbances in their
services .
One of the ways of reducing losses in the distribution
network is reconfiguration of MV distribution network .
reconfiguration is a simple and cheap way for loss reduction in
distribution systems because we don’t need to invest capital
and set up new equipment in system . we can reduce the losses
only by change the state of existing switches. there are many
goals for reconfiguration of distribution systems such as :1- reconfiguration in order to loss reduction.
H.Bagheri tolabi, with Islamic Azad university Khorramabad branch,Iran (e-mail: hajar.bagheri@gmail.com).
M.Gandomkar is currently lecturer of Islamic Azad university Savehbranch , Iran.
2- reconfiguration in order to load balancing.
3- reconfiguration in order to increase stability and improving
voltage profile .
4- reconfiguration in order to increase reliability of network .
5- reconfiguration in order to minimizing the times cutting off
electrical current for services and …
II. PROBLEM DESCRIPTION AND FORMULATION
The distribution system is the final stage in the transfer of
power to individual customers. Typically, it commences from
the secondary of the sub-transmission station transformers, andnormally consists of two levels – primary distribution or
medium voltage (MV) level, and the secondary distribution or
low voltage (LV) level.
There are two types of switch in primary distribution
systems:
normally closed switch which connects line sections, and
normally open switch on the tie-lines which connects two
primary feeders, or two substations or loop-type laterals.
Network reconfiguration(or feeder reconfiguration) is the
process of altering the topological structures of the distribution
feeders by changing the open/close status of the sectionalizing
and tie switch [1]. In general, distribution loads show different
characteristics according to their corresponding distributionlines and line sections.
Therefore, load levels for each time period can be regarded as
non identical. In the case of a distribution system with some
overloaded and some lightly loaded branches, there is the need
to reconfigure the system such that loads are transferred from
the heavily loaded to less loaded feeders. The maximum load
current which the feeder conductor can take may be considered
as the reference. Nevertheless, the transfer of load must be
such that a certain predefined objective is satisfied. In this
case, the objective is to ensure the network has minimum real
power loss. Consequently, reconfiguration may be redefined as
the rearrangement of the network such as to minimize the total
real power losses arising from line branches. Mathematically,the total power loss can be expressed as follows [7]–[9]:
∑=
+ L
i i
ii
i
V
QPr
1
22
(1)
V V V iiimaxmin
≤≤
where ir ,i
P ,i
Q and V iare respectively, the resistance, real
power, reactive power, and voltage of branch , and L is the
8/9/2019 Reconfiguration and Load Balancing By Software Simulation In A Real Distribution Network for Loss Reduction
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Canadian Journal on Electrical and Electronics Engineering Vol. 2, No. 8, August 2011
387
total number of branches in the system. The aim of this study
is to minimize the power loss represented by (1) subject to the
following constraints. The voltage magnitude of each node of
each branch must lie within a permissible range. Here a branch
can be a transformer, a line section or a tie line with a
sectionalizing switch.
III. The information needed to design 20kv khorramabad
single line diagram in CYMDIST software environment
For simulation MV distribution network of Khorram Abad
in software environment and attention to the equations (1) in
previous section, the necessary information are included
details of local and electrical conditions of feeders , stations
and substations , the impedance of lines , load of transformers,
and … .
we received them from Electricity Distribution Company of
Lorestan . Due to the large volume of the information ,as an
example the limited information from a station listed in table
1.
TABLE I INITIAL INFORMATION OF SAMPLE STATION
IV. simulation of 20kv network in CYME software
environment
First considering received information such as the kinds of
impedances, peak load of buses, properties of lines, distances,
switches and …,the single line diagram with all details was
designed, which can be seen in figure 1 .
A. power flow analysis and calculate the losses before
reconfiguration
with complete information of network in the software
environment, after power flow analysis on feeders, the total
amount of losses under the title "losses before reconfiguration"
calculated that was nearly equivalent to 4066 kw. Due to large
number of feeders ,for example one report loss of the
"goldasht" feeder is shown in table 2 . its loss is about 196.8
kw.
Figure 1. 20kv single line diagram of khoramabad in software
environment
TABLE 2
REPORT OF LOSSES FOR A SAMPLE FEEDER IN THE
SOFTWRAE ENVIRONMENT
B. reconfiguration for network Initial Results
The network reconfiguration operates with opening and
closing 4 suitable switches.
Beginning with opening the 14408NH 47320 key and
closing 14408 SB 46020 key, some of load would be
transferred from one feeder to another, and losses will be
reduced a little. finally with the opening 12403NH53610 key
and closing 1240NH53530 key losses reduce about 116 kw .
Entirely, in this reconfiguration amount of loss reduction is
about 2.87 percent .the results are shown in tables 3 and 4 .the
proposed keys schematic on single line diagram can be seen inin figures 2 and 3 .
TABLE 3
REPORT OF SWITCHES POSITION IN INITIAL
RECONFIGURATION
stationfeeder
Peak
of
load
(A)
Total
length
(KM)End of line
ghaziabad
20 MVA
shagayeg2108.5
charahban
k
saheli1655.7parkeshahr
maicrowave1105.6ostandari
goldasht17017
Goldashte
gharbi
poshteh1904.7poshteh
koyefelstin1204.7ghaziabadshariati703.5meidan
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Canadian Journal on Electrical and Electronics Engineering Vol. 2, No. 8, August 2011
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TABLE 4
REPORT OF INITIAL RECONFIGURATION AND REDUCTION OF
LOSSES
Figure 2. schematic of 1 and 2 keys in the initial reconfiguration
Figure 3. schematic of 3 and 4 keys in the initial reconfiguration
TABLE 5
REPORT OF SWITCHES POSITION IN RENEWED
RECONFIGURATION
C. Renewed reconfiguration with proposed keys by the
software
With a renewed reconfiguration and put 20 number of
proposed keys by the software
in new positions ,the amount of total losses will be reduced.
the proposed keys in the table 5 and report of loss reduction inthe table 6 are shown. with renewed reconfiguration the loss
will be minimized and reduced about 6.34 percent .
you can see the complete report in the appendix of this
article. due to a large number proposed keys on single line
diagram ,we ignore showing all of their schematics and the
keys 3 ,4 ,5,16 and 17th
will be represented in figures 4 and 5.
TABLE 6
REPORT OF RENEWED RECONFIGURATION AND REDUCTION
OF LOSSES
Figure 4. schematic of 4 and 16 keys in the renewed reconfiguration
Figure 5. schematic of 3, 5 and 17 keys in the renewed reconfiguration
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Canadian Journal on Electrical and Electronics Engineering Vol. 2, No. 8, August 2011
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V. Optimum reconfiguration and load balancing in the
network
We can see load imbalance of phases in Abnormal
Conditions report before reconfiguration.
After the optimal reconfiguration and power flow analysis
the load imbalances and consequently total losses will be
reduced . as an example , you can see the condition of"Parkesaheli" feeder before and after load balancing in tables
7, A and B. after reconfiguration in this feeder, the number of
overloads and low voltages consecutive will be decrease from
8 and 6 to 6 and 4 numbers, and total losses will be reduce
about 4.58 kw.TABLES 7 (A AND B)
REPORT OF LOAD IMBALANCES AND RELEVANT LOSSES IN
PARKSAHELI FEEDER
A) before reconfiguration
B) After reconfiguration
VI. CONCLUSIONS
In this paper, we study and simulate the Khorramabad MV
distribution network in CYMDIST software and calculate total
losses and load imbalance by power flow analysis before and
after optimal reconfiguration .results show that the total losses
and load imbalances will be reduced by suitable switch
optimization .With a renewed reconfiguration and put the 20 number of
proposed keys by software in new positions ,the amount of
total losses will be reduced maximally .
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Canadian Journal on Electrical and Electronics Engineering Vol. 2, No. 8, August 2011
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APPENDIX
Full report of renewed reconfiguration by the software proposed keys relevant IV.C part.
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BIOGRAPHIES
8/9/2019 Reconfiguration and Load Balancing By Software Simulation In A Real Distribution Network for Loss Reduction
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Canadian Journal on Electrical and Electronics Engineering Vol. 2, No. 8, August 2011
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Majid. Gandomkar:He was born in the Saveh from IRAN. He is PHD
degree of Electrical Engineering from Science and Research Branch of
Islamic azad university.his research interests are distribution systems, DG
systems ,optimization and etc. Now, he is assistant professor at Islamicazad university, Saveh branch.
Hajar.Bagheri Tolabi: She was born
in the Khorramabad from IRAN. Shereceived her B.Sc. degree Electrical
Engineering field in 2005 of the Bu-Ali
Sina University and M.Sc on power
engineering of Saveh branch Azad
University in 2009. Her researchinterests are included distributionsystems, optimization , renewableenergy.
Mohammad.Bahreini Borujeni: He is electricalengineer and now the Director of Electricity
Distribution Company of Lorestan. his research
interests are distribution systems and power
systems.
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