International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
Minimizing the Transmission Line Loss by Using Interline
Power Flow Controller
V. Suryanarayana reddy1, Dr.A.lakshmi devi2
1
M.Tech Student, 2Professor (M.Tech, PhD),
Dept of Electrical and Electronics Engineering, SVU College, Andhra Pradesh, India
Abstract
In this paper it shows the ability of interline power
flow controllers (IPFCs) to reduce the transmission
line loss in power system. In this IPFC belongs to a
series of compensating flexible alternating current
transmission system (FACTS) devices and it has the
capability to control the power flow in multiline
transmission systems. It has voltage source
converters (VSCs), it can be adjustable for to
regulate the power flow in a particular line. In this
paper, shows the capability of IPFCs to reduce
transmission loss. First, a general introduction to
the FACTS devices is developed, and the problem a
is studied. After that, the selection of parameters of
the IPFC controller is considered .The optimization
problem and the parameters are tuned by applying
intelligent search technique differential evolution
(DE) finally, the effectiveness of the device in
reducing the line loss is shown using MATLAB
software application
I .INTRODUCTION
Electric usages are now forced to operate their
system in abetter way that makes good utilization of
existing transmission facilities. A number of
Flexible AC Transmission System (FACTS)
controllers, based on the fast development of power
electronics technology, have been studied in recent
years for better utilization for existing transmission
devices [1]. One of the problems such a stressed
system is the threat of line loss in transmission. For
so many years, one of the major interests of power
usages are the improvement of transmission. FACTS
devices are found to be very usable for improving
the transmission line loss [2]. An interline Power
Flow Controller (IPFC) is a newFACTS device.It is
the mixture of two or more SSSCs
connected
through a common DC link. So With this
configuration, IPFC having thecapability of
controlling the active power exchange between
transmission lines [3]. For reduction of transmission
line loss in power system, the IPFC is must be
controlled carefully.
ISSN: 2231-5381
Inthis the trial and error method of optimization
solution is not suitable because time consuming. So
the differential evolution (DE) algorithm, was
proposed by Price and stron [4], is a suitable method
to find the pertainingoptimizer. The successful
applications of DE were shown in[4, 5, 6, and 7]
II. SYSTEMTAICAL MODEL OF IPFC
IPFC is one of The FACTS devices
used for controlling multi transmission lines of a
transmission system. An IPFC consists of two series
voltage source converters (VSCs) coupled by a dc
voltage link. The dc link is represented by a
bidirectional link for active Power exchange
between the voltage sources. This voltage source
converter is used to transfer active power in the
transmission lines and control transmission line
losses. The VSC based FACTS controller’s static
synchronous senses compensator (SSSC) is used for
the purpose of controlling in the IPFC .The
mathematical modeling of power flow in IPFC is
derived by using the Newton Raphson method. The
schematic diagram of a simple IPFC with two VSC
is shown in figure 1
In Figure 1 each of the series inverters controls
power flow by injecting fully controllable voltages
VSC 1 and VSC 2. The sending end bus voltage is
Va and the receiving end voltages are Vba and Vca. In
this series connected inverter power is generated
externally. So line losses cannot occur in this series
connected VSC1 and VSC 2. These two VSCs do
not function under normal line operating condition
and under abnormal conditions IPFC absorbs power
from these VSCs and maintains transmission line
stability
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
n
b 1,b a
n
(1)
b 1,b a
n
b 1,b a
n
b 1,b a
(2)
Figure 1 .schematic diagram of 2 line ipfc
Where
V : is the voltage magnitude
A. POWER INJECTION MODEL OF IPFC
is the bus angle
The power injection model of IPFC is
useful for calculating the injecting active power,
voltage and voltage angle in each bus. The power
calculation is based on the NR load flow algorithm.
It is used to check the loss variation before and after
connecting IPFC. The equivalent circuit for the
power injection model of IPFC is shown in Figure. 2
Figure 2.power flow model of the ipfc
In this mathematical model Va , Vb and Vc are the bus
voltages of bus a ,b and c respectively. Under
normal conditions, real power across the two
transmission lines is Re {VabIab
Vac I ac }
0.
The impedance value of this two line is Zab and Zac .
The current between the buses Va and Vb is Iab and Iac
.
The power flow equation of the
injection model IPFC is calculated as follows:
is the magnitude injected voltage
: angle of injected voltage
III .Differential Evolution Algorithm
Differential Evolution (DE)[4,5] is an evolutionary
algorithm was proposed by Price and Storn for
solving power flow problems these are nondifferential. Differential evolution solves real valued
problems based on principle of natural evolution. In
this selection process and the mutation in DE makes
it self adaptive system and because it’s simple
operation, faster, robust. Actually DE produces new
vectors of parameters by summing the weighted
difference between two population vectors to the
third one. So its resulting the individual provides a
smaller objective function value, a new individual
replaces the one with which it is similar, otherwise
the old individual is retained. The important
parameters for control in DEA is population size
(Np), scaling factor (F) and crossover constant (CR).
This about DEA
A. Implementation of DEA for IPFC
Below equation is total transmission line loss
n
J(x) =
(3)
j 1
Where n is the number of line.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
location
realpower
loss(mw)
reactivepower
loss(MVAr)
size
(MVAr)
basecase
__
5.2
23.89
_
DE IPFC
6-11
3.48
19.91
7.4to7.4
X is the control parameters
If IPFC consists of k converters the X is
Xj,G+1 = U j,Gif f (Uj,G) ≤ f (xj,G)
X j,G otherwise
X= [ x1 x2 x3 ] = [ Vs1 Vs2θs1 ] T
Where θs2 is not controlled parameter members. It
must be regulated in the such a manner that the net
active power exchange between converter is zeros.
Thus the objective function is shown by
The step of DE to obtain the optimization of (3) can
be summarized by following steps[8]:
a. Initialization
The first one is to initialize the solution vectors are
shown below
Xj,G = { x1j,G,…., xDj,G} j=1 ,n
(4)
wheren is number of populations
G is number of generations
D is number of control parameters
The equation of random solution is given by
Xij,0 =
i
X min
i
i
+ rand(0,1).(X max - X min)i = 1,,… D
(5)
Here
b. Mutation
next is DE applies mutation operation to produce
mutant vector
belongs with targetvector. The DE,one of the
mutation strategies, is given by
M j, G= Xr1j, G + F(X ri2, G – X ri3, G) i = 1…n (6)
Here Xrj,G is target vectors
F is a positive scaling factor
c. Crossover
The crossover operation is used for generating the
trail
vector
binomial
equation of crossover operation is written by
Uij,GI
mIj,G if (rand I [0,1)≤ CR or (i=i rand))
=
xij,G other wise
ISSN: 2231-5381
d. Selection
In this the selective objective function values are,
the control parameters are changed by mutation
vector and target vector. The next changing of target
vector (Xj,G1) is selected by
The above steps are repeated until the objective
function is obtained
IV. Power flow calculation of IPFC
The power flow calculations of IPFC are performed
using basic load flow formulas. Using the basic
formulas real power, bus voltage and voltage angles
are calculated for IPFC connected lines. Thus the
improvement in real power and loss variation of the
IPFC connected transmission lines are determined
easily. Once the real power and transmission losses
are determined the amount of IPFC stabilized losses
can be calculated. Several methods are available to
solve the power flow of a system and NR is the one
of the most popular methods. The general power
flow solution of Newton Raphson (NR) is explained
as follows.
1. Initialize all the unknown variables such as
voltage magnitude is set as 1 p.u and voltage angle is
set as zero.
2. Calculate the Y-bus matrix.
3. Solve the power balance equation using recent
voltage magnitude and angle.
4. Create Jacobian matrix corresponding to the
power mismatch.
5. Set the determined voltage magnitude and voltage
angle.
6. Solve the change in voltage angle and magnitude.
7. Update the voltage magnitude and angle.
8. Check the stopping conditions, if met then
terminate, else go to step 3.
This process is continued until a predetermined
condition is satisfied. A common stopping condition
is to terminate if the power mismatch equation is
below the tolerance value.
A. RATINGS OF IPFC
V .RESULTS AND DISCUSSION
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
The suggested technique is implemented in
MATLAB platform and it is tested on IEEE-14 bus
system. The diagram of tested bus system and output
are shown in Figure 3. In this tested system bus 1 is
selected as slack bus, bus 2 is generated bus and the
other buses are load buses. The base voltage of slack
bus is selected as 1 p.u (per unit) and angle is
selected as 0. Tables 1 are load data of the standard
bus system before connecting IPFC. Table 2 are
load data of IPFC connected in two lines .The two
lines selected are from 3 ,4and5 buses.Table 3 are
load data of IPFC connected inmulti lines. The IPFC
connected lines are selected from bus number 6 to
11
TABLE 1 : LOAD DATA FOR WITHOUT IPFC
from
bus
To
bus
1
2
1
2
2
2
3
4
4
4
5
6
6
6
7
7
9
9
10
12
13
Loss (I^2 * Z)
From BusInjection
To BusInjection
P(MW)
Q(MVAr)
p(MW)
Q(MVAr)
P(KW)
Q(KVAr)
156.8
-20.4
-152.5
27.68
5747.09
5
75.21
3.85
-72.75
2.23
3
4
5
4
5
7
9
6
11
12
13
8
9
10
14
11
13
14
73.24
3.56
56.13
-1.55
41.52
1.17
-23.2
4.47
-61.1
15.82
28.07
-9.6
16.08
-0.43
44.09
12.47
7.35
3.56
7.79
2.50
17.75
7.22
-0.00
-17.1
28.07
5.78
5.23
4.22
9.43
3.61
-3.79
-1.62
1.61
0.75
5.64
5.64
TOTAL
-70.91
-54.45
-40.61
23.66
61.67
-28.07
-16.08
-44.09
-7.30
-7.71
-17.54
0.000
-28.07
-5.21
-9.31
3.80
-1.61
-5.59
1.60
3.02
-2.10
-4.84
-14.20
11.38
1.73
-8.05
-3.44
-2.35
-6.80
17.62
-4.98
-4.18
-3.36
1.64
-0.75
-1.64
1668.54
3
1072.68
5
902.009
650.962
350.882
144.990
199.723
0.000
0.000
0.000
21.449
27.880
82.342
0.000
0.000
4.999
45.097
4.885
2.445
20.996
5199.93
8
4995.54
4287.14
2228.20
1208.59
417.48
710.72
746.01
571.46
1936.47
50.79
65.46
182.94
201.69
351.31
14.98
108.22
12.90
2.50
48.23
23887.7
8
TABLE 2 : LOAD DATA FOR WITH IPFC PLACING BETWEEN 3-5
Fig: IEEE 14-bus system
from
To
From BusInjection
To BusInjection
Loss (I^2 * Z)
bus
bus
P(MW)
Q(MVAr)
p(MW)
Q(MVAr)
P(KW)
Q(KVAr)
1
2
156.8
-20.4
-152.5
27.68
1625.352
5510.91
1
5
75.21
3.85
-72.75
2.23
1044.918
4790.25
2
3
73.24
3.56
-70.91
1.60
878.660
4110.96
2
4
56.13
-1.55
-54.45
3.02
634.112
2136.70
2
5
41.52
1.17
-40.61
-2.10
341.800
1158.92
3
4
-23.2
4.47
23.66
-4.84
141.290
400.32
4
5
-61.1
15.82
61.67
-14.20
194.553
681.51
4
7
28.07
-9.6
-28.07
11.38
0.000
715.35
4
9
16.08
-0.43
-16.08
1.73
0.000
547.98
5
6
44.09
12.47
-44.09
-8.05
0.000
1856.89
6
11
7.35
3.56
-7.30
-3.44
20.942
48.70
6
12
7.79
2.50
-7.71
-2.35
27.158
62.77
6
13
17.75
7.22
-17.54
-6.80
80.211
175.42
7
8
-0.00
-17.1
0.000
17.62
0.000
193.40
7
9
28.07
5.78
-28.07
-4.98
0.000
336.87
9
10
5.23
4.22
-5.21
-4.18
4.869
14.36
9
14
9.43
3.61
-9.31
-3.36
43.929
103.77
10
11
-3.79
-1.62
3.80
1.64
4.758
12.37
12
13
1.61
0.75
-1.61
-0.75
2.382
2.39
13
14
5.64
5.64
-5.59
-1.64
20.452
46.23
5065.336
22469.7
TOTAL
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
3. L. Gyugyi, K.K.Sen, C.D.Schauder, “The interline power
flow controller concept: A new approach to power flow
management in transmission line system”, IEEE Trans. on
Power Delivery, Vol. 14, No. 3, 1999, pp. 1115-1123.
TABLE 3 : IPFC PLACING BETWEEN 6-11
from
bus
To
bus
FromBusInjection
ToBusInjection
Loss (I^2 * Z)
P(MW)
p(MW)
P(KW)
-152.5
Q(MVA
r)
27.68
1117.37
Q(KVA
r)
4789.24
1
2
156.8
Q(MV
Ar)
-20.4
1
5
75.21
3.85
-72.75
2.23
718.347
4162.95
2
3
73.24
3.56
-70.91
1.60
604.050
3572.62
2
4
56.13
-1.55
-54.45
3.02
435.931
1856.90
2
5
41.52
1.17
-40.61
-2.10
234.976
1007.16
3
4
-23.2
4.47
23.66
-4.84
97.096
347.90
4
5
-61.1
15.82
61.67
-14.20
133.749
592.26
4
7
28.07
-9.6
-28.07
11.38
0.000
621.6
4
9
16.08
-0.43
-16.08
1.73
0.000
476.22
5
6
44.09
12.47
-44.09
-8.05
0.000
1613.72
6
11
7.35
3.56
-7.30
-3.44
14.397
42.32
6
12
7.79
2.50
-7.71
-2.35
18.670
54.55
6
13
17.75
7.22
-17.54
-6.80
55.142
152.45
7
8
-0.00
-17.1
0.000
17.62
0.000
168.08
7
9
28.07
5.78
-28.07
-4.98
0.000
292.76
9
10
5.23
4.22
-5.21
-4.18
3.347
12.48
9
14
9.43
3.61
-9.31
-3.36
30.200
90.18
10
11
-3.79
-1.62
3.80
1.64
3.271
10.75
12
13
1.61
0.75
-1.61
-0.75
1.638
2.08
13
14
5.64
5.64
-5.59
-1.64
14.060
40.19
3482.25
1
19906.4
TOTAL
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Page(s):398 - 417
VI.CONCLUSIONS
In This paper applied the Interline Power Flow
Controller to reduce the transmission line loss. The
IPFC is basically modeled as a multi-series voltage
injection. The mathematical model indicates that
IPFC can control both active and reactive power
flows. This paper uses differential evolution to
control
IPFC
parameter
for
improving
the
transmission line loss. The implementing method
was tested on multi-machinesystem. These results
indicated that IPFC can reduce total active and
reactive power
REFERENCES
1. S.Teerathana, A. Yokoyama, Y.Nakachi and M. Yasumatsu,
“An Optimal Power Flow Control Method of Power System
by Interline Power Flow Controller (IPFC)”, in Proc. the
7thInt. Power Engineering Conf., pp 1-6
2. N.G. Hingorani and L. Gyugyi, “Understanding FACTS:
concepts and technology of flexible ac transmission
systems”, IEEE Press, NY, 1999.
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