POWER LOSS REDUCTION IN ELECTRICAL DISTRIBUTION SYSTEMS USING CAPACITOR PLACEMENT

International Journal of Technical Research and Applications e-ISSN: 2320-8163,
www.ijtra.com Volume 3, Issue 3 (May-June 2015), PP. 147-152
147 | P a g e
POWER LOSS REDUCTION IN ELECTRICAL
DISTRIBUTION SYSTEMS USING CAPACITOR
PLACEMENT
N. A. Uzodife1
, A. J. Onah2
, T. C. Madueme3
1
Federal Ministry of Defence, Abuja.
2
Department of Electrical/Electronic Engineering, Michael Okpara University of Agriculture, Umudike.
3
Department of Electrical Engineering, University of Nigeria, Nsukka.
uzodifenichodemus@yahoo.com, aniagbosoonah@yahoo.com, theophilus.madueme@unn.edu.ng
Abstract- As power factor falls below unity the current
in the system increases with the following effects: I2
R power
loss increases in cables and windings leading to overheating
and consequent reduction in equipment life; cost incurred by
power company increases and efficiency as a whole suffers
because more of the input is absorbed in meeting losses.
Distribution losses cost the utilities a very big amount of profit
and reduce life of equipment. The system is considered as
efficient when the loss level is low. So, attempts at power loss
minimization in order to reduce electricity cost, and improve
the efficiency of distribution systems are continuously made.
This paper investigates the losses in a 34-bus distribution
system and how the installation of capacitors at some points in
the system can significantly reduce losses in circuits and cables,
ensure that the rated voltage is applied to motors, lamps, etc, to
obtain optimum performance, ensure maximum power output
of transformers is utilized and not used in making-up losses,
enables existing transformers to carry additional load without
overheating or the necessity of capital cost of new
transformers, and achieve the financial benefits which will
result from lower maximum demand charges.
Keywords: Losses, Power factor, Reactive power,
Capacitor, Distribution system, Loss reduction.
I. INTRODUCTION
The Enugu distribution system is the case study. The
type of losses, the causes of losses and methods of loss
reduction in distribution system are presented. A method
based on a heuristic technique for reactive loss reduction in
distribution system is applied in this work because it
provides realistic sizes and locations for shunt capacitors on
primary feeder at a low computational burden. The variation
of the load during the year is considered. The capital and
installation cost of the capacitors are also taken into account.
The economical power factor is also determined so as to
achieve maximum savings. This method is applied to a 34
bus, 11KV, 6MVA distribution system with original power
factor of 0.85.
A. Losses In Distribution Lines
A significant portion of the power that a utility
generates is lost in the distribution process. These losses
occur in numerous small components in the distribution
system, such as transformers and distribution lines. Due to
the lower power level of these components, the losses
inherent in each component are lower than those in
comparable components of the transmission system. While
each of these components may have relatively small losses,
the large number of components involved makes it
important to examine the losses in the distribution system
[1]. One of the major sources of losses in the distribution
system is the power lines which connect the substation to
the loads. Virtually all real power that is lost in the
distribution system is due to copper losses. Since these
losses are a function of the square of the current flow
through the line, it should be obvious that the losses in
distribution lines are larger at high power levels than they
are at lower levels. Power loss in the distribution lines can
be considered to be entirely due to copper losses given as:
PL = I2
R (1)
A significant portion of the power that a utility
generates is lost in the distribution process. These losses
occur in numerous small components in the distribution
system, such as transformers and distribution lines. Due to
the lower power level of these components, the losses
inherent in each component are lower than those in
comparable components of the transmission system. While
each of these components may have relatively small losses,
the large number of components involved makes it
important to examine the losses in the distribution system
[1]. One of the major sources of losses in the distribution
system is the power lines which connect the substation to
the loads. Virtually all real power that is lost in the
distribution system is due to copper losses. Since these
losses are a function of the square of the current flow
through the line, it should be obvious that the losses in
distribution lines are larger at high power levels than they
are at lower levels. Therefore, a long line will have a higher
resistance and larger losses than a short line with the same
current flow. Similarly, a large conductor size results in a
smaller resistance and lower losses than a small conductor.
The resistivity is determined by the material of which the
line is constructed and the temperature of the material. A
better conducting material will result in lower resistivity and
lower losses. The resistivity of the metal in the line will be
affected by the temperature. As the temperature of the metal
increases, the line resistance will also increase, causing
higher copper losses in the distribution line. The resistivity
of copper and aluminum can be calculated from the
following equation.
o
o
TT
TT



1
2
21  (2)
The letter rho (ρ) is the resistivity at a specific temperature.
It is equal to
8
1083.2 
 ohm meters for aluminum and
8
1077.1 
 ohm meters for copper at a temperature of
20o
C. T0 is a reference temperature and is equal to 228o
C for
aluminum and 241o
C for copper. 1 and 2 are the
resistivity at temperature T1 and T2 respectively [2].

148 | P a g e
B. Losses In Distribution Transformers
While losses in distribution lines are virtually all due to
copper losses, transformer losses occur due to both copper
and core losses. The core losses are made up of eddy current
and hysteresis losses. The copper losses in transformers are
essentially the same as those in the power distribution lines.
The copper losses in a transformer are smaller in magnitude
than the core losses. These losses occur in the form of heat
produced by the current, both primary and secondary,
through the windings of the transformer. Like the copper
loss in the distribution line, it is calculated using the I2
R
relationship of Equation 2.1. Any factor which affects either
current or winding resistance will also affect the amount of
copper loss in the transformer. An increase in loading, either
real or reactive, will result in an increase in current flow and
a correspondingly greater amount of loss in the transformer.
Additionally, an unbalanced system load will increase
transformer loss due to the squared current relationship. The
winding resistance also has an effect on the amount of
copper loss and is mainly determined by the total length of
the wire used, as well as the size of the wire. Temperature of
the winding will affect the resistivity of the wire, therefore
affecting the overall resistance and the copper loss. Since all
but the smallest distribution transformers have some type of
cooling system, such as immersion in oil, the temperature
effect on losses is usually minimal.
The core loss in a transformer is usually larger in
magnitude than the copper loss. It is made up of eddy
current losses, which are due to magnetically induced
currents in the core, and hysteresis losses, which occur
because of the less than perfect permeability of the core
material. These losses are relatively constant for an
energized transformer and can be considered to be
independent of the transformer load. Transformer core
losses have been modeled in various ways, usually as a
resistance in parallel with the transformer’s magnetizing
reactance [2], [3], [4]. Since the core loss is relatively
independent of loading, the most important factor when
considering core loss is the manufacture of the core. The
physical construction of the core has serious consequences
on the amount of core loss occurring in the transformer. For
instance, eddy currents are greatly reduced by using
laminated pieces to construct the core. These thin sheets are
oriented along the path of travel of the magnetic flux and
restrict the amount of reduced currents that occur. [4] The
hysteresis loss occurs in the transformer core due to the
energy required to provide the magnetic filed in the core as
the direction of magnetic flux alternates with the alternating
current wave form. This energy is transformed into heat.
Hysteresis loss can be reduced by the use of higher quality
materials in the core which have better magnetic
permeability [5] [6]. A final aspect of the distribution
system that increases losses in the transformers is the
presence of harmonics in the system. The harmonic currents
only cause a small increase in copper losses throughout the
system. However, the high frequency harmonic voltages can
cause large core losses in the transformer. Frequently,
utilities are forced to use an oversized transformer to
compensate when a large harmonic presence is indicated.
The increased skin effect of larger conductors combined
with the high frequency harmonics can result in even greater
losses [7].
II. DEFINITION OF TERMS
Power factor is the ratio of Active Power (P) to the Apparent
Power (S) as shown in Fig. 1


cos
cos
)(
)(

S
S
S
P
KVApowerApparent
WpowerActive
factorPower
(3)
Fig. 1 Power diagram
Inductive components, such as ballasts, draw reactive
power, Q (Var) from the mains. It lags behind the Active
Power, P (W) by 90o
(Figure 2.1). A capacitor, if connected
across the mains, will also draw reactive power, but it leads
the active power by 90o
. The direction of the capacitive
reactive power
(QC) is opposite to the direction of the inductive reactive
power (QL) (Figures 2 and 3)
Fig. 2 Capacitive power loss reduction
Fig. 3 Phasor diagram for Fig. 2
If a capacitor is connected in parallel with an inductive load,
it will draw capacitive leading reactive power. The effective
reactive power drawn by the circuit will reduce to the extent
of the capacitive reactive power, resulting in reduction of
apparent power from S1 to S2. The phase angle between the
active power and the new apparent power S2 will also
reduce from 1 to 2 (Fig. 2). Thus the power factor will
increase from cos 1 to cos 2 . The reactive power
supplied by the capacitor is thus given by:
 2121 tantan   PQQQ LLC (4)

149 | P a g e
Fig. 4 Current Phasor diagram for Fig. 2
After compensation (capacitor is switched on) Is
decreases to Is1 i.e., reactive component of Is decreases from
1sinsI to 21 sinsI
211 sinsin  ssc III  (5)
As shown in Fig. 4
1
1
COS
W
KVA  (6)
1
1
tan
W
KVAr  (7)
Suppose by installing capacitors he power factor rises to
cos 2 (his power consumption P remaining the same),
then
2
2
COS
W
KVA  (8)
2
2
tan
W
KVAr  (9)
Reduction in KVA maximum demand is
 21 KVAKVA  = 






21  COS
W
COS
W
(10)
If charge is NA per KVA maximum demand, annual saving
on account is:
A







21  COS
W
COS
W
KVAr is reduced from KVAr1 to KVAr2, the difference
KVAr1 - KVAr2 = W tan 1 - W tan 2 being neutralized by
the leading KVAr supplied by the capacitors. The cost of
power factor improvement equipment is taken into account
by way of interest on capital required to install it plus
depreciation and maintenance expenses. Thus, the greater
the KVAr reduction, the more costly the P.F improvement
capacitor and hence greater the charge on interest on capital
outlay and depreciation. A point is reached in practice when
any further improvement in power factor, cost more than
saving in the bill. Hence it is necessary for the consumer to
find out the value of power factor at which his net savings
will be maximum. The value can be found if:
(i) Annual charge per KVA maximum demand and
(ii) The cost per KVAR rating of capacitor are known.
If the cost per KVAR of capacitor is NB and the
rate of interest and depreciation is U percent per year, then
its cost per annum is
If the cost per KVAR of capacitor is NB and the rate of
interest and depreciation is U percent per year, then its cost
per annum is
 21 tantan
100
 PP
UB


Assuming
A
UB
C
100
*
 (11)
Cost per annum =  21 tantan  PPC  (12)
Net annual saving S is
S= A







21  COS
P
COS
P - C  21 tantan  PP  (13)
This net savings is maximum when 0
2

d
dS
(14)
Therefore
22  d
d
d
dS
 [A  2tan1tan
coscos 21


PPC
PP







(15)
     0tantansecsec 2121
22
 

CPAP
d
d
d
dS (16)
    0sectansec 2
2
22   CPAP
2
2
22 sectansec  CPAP 
2
2
22 sectansec  CA 
22 sectan  CA 
2
2
sec
tan


A
C
 22
2
2
22
2
2
2
2
sincos*
cos
sin
sec
1
*
cos
sin
sec
cos
sin








(17)
Recall that
1cossin 22
 
Therefore













A
UB
A
C
100
*
11sin1cos
2
2
2 
(18)
From this expression θ2 and hence cosθ2 can be found.
Investigation shows that the current charge per KVA by
PHCN is two hundred and fifty Naira (N250.00). As for
compensating capacitors, the cost per KVAR is about seven

150 | P a g e
hundred Naira (N700.00) and interest on the capital plus
depreciation and maintenance expenses is taken as 10%.
From the above expressions, the economical power factor
for this project can be found as follows: Let the charge per
KVA maximum demand be N250.00 =A. The cost per
KVAR rating be N700.00 = B
Rate of interest plus depreciation and maintenance expenses
is:
U =10%
o
Cos
Sin
A
C
xUB
C
3.1696.0cos
96.0
25
7
1
25
7
250
70
70
100
10700
100
1
2
2
2
2
















Therefore, the optimal economical power factor for this
project is cos 2 = 0.96.
Net savings = cost of KVA before compensation – (cost of
KVA after compensation + cost of capacitor)
Time required to save the initial cost of capacitor is
N
ZY
T
*
 years
(19)
Where
Y = Value of capacitor in Kvar
Z = Cost of capacitor per Kvar in Naira
Y*Z = Total cost of installed capacitor in Naira
N = Net saving in Naira
Net savings is the amount that is saved by reducing losses
after discounting the investment in equipment acquisition
and its installation.
III. LOSS CALCULATION IN A 34-BUS
DISTRIBUTION SYSTEM
Fig. 4 34-bus distribution network
Table 1 Bus Data
Bus No Load
P Kw Q(Kvar)
1 0 0
2 230 142.5
3. 0 0
4 230 142.5
5 230 142.5
6 0 0
7 0 0
8 230 1425
9 230 142.5
10 0 0
11 230 142.5
12 137 84
13 72 45
14 72 45
15 72 45
16 13.5 7.5
17 230 142.5
18 230 142.5
19 230 142.5
20. 230 142.5
21 230 142.5
22 230 142.5
23 230 142.5
24 230 142.5
25 230 142.5
26 230 142.5
27 137 85
28 75 48
29. 75 48
30 75 48
31 57 34.5
32 57 34.5
33 57 34.5
34 57 34.5
Table 2 Line Data
Line Impedance Length
(Km)
Impedance
Line No  Kmr   Kmx  r +jX  
1-2 0.195 0.080 0.60 0.117 + j0.048
2-3 0.195 0.080 0.55 0.10725 + j0.044
3-4 0.299 0.083 0.55 0.16445+ j0.04565
4-5 0.299 0.083 0.50 0.1495 + j0.0415
5-6 0.299 0.083 0.50 0.1495 + j0.0415
6-7 0.524 0.090 0.60 0.3144+j0.054
7-8 0.524 0.090 0.40 0.2096+j0.036
8-9 0.524 0.090 0.60 0.3144+j0.054
9-10 0.524 0.090 0.40 0.2096+j0.036
10-11 0.524 0.090 0.25 0.131+ j0.0225
11-12 0.524 0.090 0.20 0.1048 + j0.018
3-13 0.524 0.090 0.30 0.1572+j0.027
13-14 0.524 0.090 0.40 0.2096 + j0.036
14-15 0.524 0.090 0.20 0.1048 + j0.018
15-16 0.524 0.090 0.10 0.0524 + j0.009
6-17 0.299 0.083 0.60 0.1794 + j0.0498
17-18 0.299 0.083 0.55 0.16445 + j0.04565
18-19 0.378 0.086 0.55 0.2079 + j0.0473
19-20 0.378 0.086 0.50 0.189 + j0.043
20-21 0.378 0.086 0.50 0.189+j0.043
21-22 0.524 0.090 0.50 0.262 + j0.045
22-23 0.524 0.090 0.50 0.262 + j0.045
23-24 0.524 0.090 0.60 0.3144 + j0.054
24-25 0.524 0.090 0.40 0.2096+ j0.036

151 | P a g e
25-26 0.524 0.090 0.25 0.131+j0.0225
26-27 0.524 0.090 0.20 0.1048 + j0.018
27-28 0.524 0.090 0.30 0.1572 + j0.027
28-29 0.524 0.090 0.30 0.1572 + j0.027
29-30 0.524 0.090 0.30 0.1572 + j0.027
10-31 0.524 0.090 0.30 0.1572 + j0.027
31-32 0.524 0.090 0.40 0.2096 + j0.036
32-33 0.524 0.090 0.30 0.1572 + j0.027
33-34 0.524 0.090 0.20 0.1048 + j0.018
The admittance to a bus,
V
I
Y  (20)
The distribution system is characterized by a system of n
nonlinear equations of the form in (24). Therefore (24) can
be written as
[Ibus] = [Ybus] [Vbus] (21)
Where: n is the number of buses in the system.
Ibus is the bus current vector
Vbus is the bus voltage vector
Ybus is the bus admittance
Thus, from Fig.4 the net current injected into the network at
bus 3, for instance is:
    1313344333313313334433 VYVYVYYVVYVVI   (22)
Where 1334333   YYY
Hence if 3 is denoted by i the current into bus 3 is given as:

 
N
n
nniiiii VYVYVYVYI
3
13134433
(23)
*
*
i
ii
i
i
i
V
jQP
V
S
I







 (24)


N
n
nniiii VYVjQP
3
*
(25)










 

131344*
3
3
1
VYVY
V
jQP
Y
V ii
i
ii
i
(26)
Applying the Gauss-Seidel iterative method [8],
equation (26) can be used to determine all the bus voltages
and thereafter, equation (22) is applied to solve for the line
currents. The results of these computations are shown in
table 3
LOAD FLOW RESULTS
Table 3 Voltages and Currents in the Distribution System
Bus Voltages (per
Unit)
Line Currents (Per Unit) Line Currents (A) Load Currents (Per Unit) Load Currents (A)
V1 = 1.00
V2 = 0.9941 + 0.0009i
V3 = 0.9890 + 0.0017i
V4 = 0.9820 + 0.0037i
V5 = 0.9761 + 0.0053i
V6 = 0.9704 + 0.0069i
V7 = 0.9666 + 0.0084i
V8 = 0.9644 + 0.0092i
V9 = 0.9620 + 0.0102i
V10 = 0.9608 + 0.0107i
V11 = 0.9603 + 0.0108i
V12 = 0.9602 + 0.0109i
V13 = 0.9887 + 0.0018i
V14 = 0.9884 + 0.0020i
V15 = 0.9883 + 0.0020i
V16 = 0.9883 + 0.0020i
V17 = 0.9659 + 0.0081i
V18 = 0.9622 + 0.0092i
V19 = 0.9581 + 0.0105i
V20 = 0.9548 + 0.0116i
V21 = 0.9519 + 0.0125i
V22 = 0.9486 + 0.0138i
V23 = 0.9459 + 0.0148i
V24 = 0.9434 + 0.0158i
V25 = 0.9422 + 0.0163i
V26 = 0.9417 + 0.0165i
V27 = 0.9416 + 0.0165i
V28 = 0.9664 + 0.0085i
V29 = 0.9662 + 0.0085i
V30 = 0.9661 + 0.0086i
V31 = 0.9604 + 0.0108i
V32 = 0.9601 +
0.01090i
V33 = 0.9599 + 0.0110i
V34 = 0.9599 + 0.0110i
i2 = 0.0486 – 0.0294i
i3 = 0.0463 – 0.0280i
i4 = 0.0439 – 0.0265i
i5 = 0.0416 – 0.0251i
i6 = 0.0392 – 0.02361i
i7 = 0.0134 – 0.0081i
i8 = 0.0110 – 0.0066i
i9 = 0.0086 – 0.0052i
i10 = 0.0062 – 0.0037i
i11 = 0.0038 – 0.0023i
i12 = 0.0014 – 0.0009i
i13 = 0.0023 – 0.0014i
i14 = 0.0016 – 0.0010i
i15 = 8.6615e-004-
5.2947e-004i
i16 = 1.3704e-004 -
7.5561e-005i
i17 = 0.0258 – 0.0155i
i18 = 0.0234 – 0.0141i
i19 = 0.0210 – 0.0126i
i20 = 0.0186 – 0.0111i
i21 = 0.0162 – 0.0097i
i22 = 0.0138 – 0.0082i
i23 = 0.0113 – 0.0068i
i24 = 0.0089 – 0.0053i
i25 = 0.0064 – 0.0038i
i26 = 0.0040 – 0.0023i
i27 = 0.0014 – 0.0009i
i28 = 0.0023 – 0.0015i
i29 = 0.0016 – 0.0010i
i30 = 7.8099e-004 –
4.8990e-004i
i31 = 0.0024 -0.0014i
i32 = 0.0018 – 0.0011i
i33 = 0.0012 – 0.0007i
i34 = -5.9844e-004 –
3.5254e-004i
Ib = 5248.6
I2 = 2.5498e+002 -
1.5424e+002i
I3 = 2.4283e+002 - 1.4673e+-
002i
i4 = 2.3063e+002 – 1.3918e+002i
i5 = 2.1831e+002 – 1.2402e+002i
i6 = 2.0590e+002 – 1.2402e+002i
i7 = 70.2534 – 42.5449i
i8 = 57.9617 – 34.8303i
i9 = 45.3718 – 27.1957i
i10 = 32.7424 – 19.5543i
i11 = 20.1972 – 12.1519i
i12 = 7.5412 – 4.5060i
i13 = 12.2007 – 7.5430i
i14 = 8.3741 – 5.1612i
i15 = 4.5463 – 2.7790i
i16 = 0.7184 – 0.3966i
i17 = 1.3565e+002-8.1474e+001i
i18 = 1.2308e+002 –
7.3836e+001i
i19 = 1.1046e+002 –
6.6183e+001i
i20 = 97.7813 – 58.5160i
i21 = 85.0451 – 50.8370i
i22 = 72.2624 – 43.1480i
i23 = 59.4251 – 35.4503i
i24 = 46.5425 – 27.7454i
i25 = 33.6175 – 20.0337i
i26 = 20.6723 – 12.3188i
i27 = 7.7190 – 4.6026i
i28 = 12.2934 – 7.7141i
i29 = 8.1970 – 5.1428i
i30 = 4.0993 – 2.5713i
i31 = 12.5477 – 7.4019i
i32 = 9.4122 – 5.5516i
i33 = 6.2759 – 3.7011i
i34 = 3.1393 – 1.8502i
il2 = - 0.0023 + 0.0014i
il3 = - 0.0000 + 0.0000i
il4 = - 0.0023 + 0.0014i
il5 = - 0.0024 + 0.0014i
il6 = - 0.0000 + 0.0000i
il7 = - 0.0000 + 0.0000i
il8 = - 0.0024 + 0.0014i
il9 = - 0.0024 + 0.0014i
il10 = - 0.0000 + 0.0000i
il11 = - 0.0024 + 0.0014i
il12 = - 0.0014 - 0.0009i
il13 = - 7.2909e - 004 +4.5379e-
004i
i114 = - 7.2909e - 004 + 4.5379e-
004i
il15 = - 7.2909e-004+4.5379e-004i
il16 = - 1.3675e-004+7.56lle-005i
il17 = - 0.0024 + 0.0014i
il18 = - 0.0024 + 0.0014i
il19 = - 0.0024 + 0.0014i
il20 = - 0.0024 + 0.0014i
il21 = - 0.0024 + 0.0014i
il22 = - 0.0024 + 0.0014i
il23 = - 0.0024 + 0.0014i
il24 = - 0.0024 + 0.0014i
il25 = - 0.0024 + 0.0014i
il26 = - .00024 + 0.0014i
il27 = - 0.0014 – 0.0009i
il28 = - 7.8056e – 004 + 4.8988e-
004i
il29 = - 7.8056e – 004 + 4.8988e-
004i
il30 = - 7.8056e – 004 + 4.8988e-
004i
il31 = - 5.9744e-004 + 3.5251e-
004i
il32 = - 5.9744e-004 + 3.5251e-
004i
il33 = - 5.9744e-004 + 3.5251e-
004i
il34 = - 5.9744e-004 + 3.5251e-
004i
il2 = - 12.1500 + 7.5122i
il3 = - 0.0000 + 0.0000i
il4 = - 12.3207 + 7.5702i
il5 = - 12.4096 + 7.5951i
il6 = - 0.0000 + 0.0000i
il7 = - 0.0000 + 0.0000i
il8 = - 12.4096. + 7.5951i
il9 = - 12.4096 + 7.5122i
il10 = - 0.0000 + 0.0000i
il11 = - 12.4096 + 7.5122i
il12 = - 7.5400 – 4.5063i
il13 = - 3.8267 + 2.3818i
il14 = - 3.8267 + 2.3818i
il15 = - 3.8267 + 2.3818i
il16 = - 0.7178 + 0.3969i
il17 = - 12.4096 + 7.5951i
il18 = - 12.4096 + 7.5951i
il19 = - 12.4096 + 7.5951i
il20 = - 12.4096 + 7.5951i
i121 = - 12.4096 + 7.5951i
i122 = - 12.4096 + 7.5951i
i123 = - 12.4096 + 7.5951i
i124 = - 12.4096 + 7.5951i
i125 = - 12.4096 + 7.5951i
i126 = - 12.4096 + 7.5951i
i127 = - 7.5400 – 4.5063i
i128 = - 4.0969 + 2.5712i
i129 = - 4.0969 + 2.5712i
i130 = - 4.0969 + 2.5712i
i131 = - 3.1358 + 1.8502i
i132 = - 3.1358 + 1.8502i
i133 = - 3.1358 + 1.8502i
i134 = - 3.1358 + 1.8502i

152 | P a g e
Capacitor
banks on nodes
26 & 11
Power
factor
Power
Loss
(KW)
Power
Loss
reduction
(KW)
Net
Savings
(N) x 103
750 + 0
750 + 150
750 + 300
750 + 450
750 + 600
750 + 750
750 + 900
750 + 1050
750 + 1200
750 + 1350
750 + 1500
0.92
0.94
0.95
0.96
0.97
0.98
0.98
0.99
0.99
1.0
1.0
182.6
176.9
173.5
172.3
173.4
176.8
182.4
190.2
200.3
212.7
227.4
39.1
44.8
48.2
49.4
48.3
44.9
39.3
31.5
21.4
9
-5.7
33.4
36.7
38.8
39.5
38.9
36.9
33.4
28.5
22.1
14.2
4.8
Table 4 Power Factor and Savings due to the addition of
capacitor banks on nodes 11 and 26
Size of capacitor bank [kVAr]
Fig. 5 Net Savings per annum versus total Size of capacitor
banks on nodes 11 and 26 of Fig. 5
IV. CONCLUSION
The ability of utility to reduce technical losses in its
operation will provide enough revenue for future expansion,
upgrades and modernization. This will improve on reliability
and security of supply. Many utilities are faced with the
crippling effect of power losses (Technical) and are putting
in place various measures to reduce these losses. This
project therefore presents a technique for reducing the power
losses arising from the flow of reactive power in a
distribution system by placing compensating capacitors at a
few specific locations in the network termed “sensitive
nodes” to achieve a maximum loss reduction and maximum
annual naira savings. This method is applied to a 3-phase,
11kv, and 50Hz distribution network in Enugu. It can be
observed that capacitor bank 1200kVAr was required to
provide an optimum net saving of N 39,500.00 (thirty-nine
thousand, five-hundred naira).
REFERENCES
[1] Sun D.I.H., Abe S., Shoults R.R., Chen M.S.,
Eichenberger P. and Farris D. “Calculation of Energy
Losses in a Distribution System, “IEEE Transactions on
Power Apparatus and Systems, V. 6, PA5-99, No. 4, Jul.
1980.
[2] Gross C.A., Power System Analysis, 2nd
ed., 1986
[3] Nasar S.A., Electric Energy Conservation and Transmission,
1986
[4] Chen T.H., Chen M.S., Inoue T., Kotas P. and Chebli
E.A., “Three Phase Cogenerator and Transformer Models for
Distribution System Analysis,” IEEE Transactions on Power
Delivery, V. 6, No. 4, Oct. 1991.
[5] Makino A., Suzuki K., Inoue A. and Masumoto T., “Low
Core Loss of a bcc Fe86Zr7B6CUI Alloy with Nanoscale Grain
Size, “Materials Transactions, JIM (Japan Institute of
Metals), V. 32, No. 6, Jun. 1991.
[6] Ng H.W., Hasegawa R., Lee A.C and Lowdermilk, L.A.,
“Amorphous Alloy Core Distribution Transformers,” IEEE
Proceedings, V. 79, No. 11, Nov. 1991
[7] Kerszenbauru I, Mazur A., Mistry M. and Frank J.,
“Specifying Dry-Type Distribution Transformers for Solid-
State Applications, “IEEE Transactions on Industry
Application, V. 27, No. 1, Jan. 1991.
[8] John J. Grainger, William D. Stevenson, Jr., Power
System Analysis, McGraw-Hill, Inc., 1994.

POWER LOSS REDUCTION IN ELECTRICAL DISTRIBUTION SYSTEMS USING CAPACITOR PLACEMENT

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POWER LOSS REDUCTION IN ELECTRICAL DISTRIBUTION SYSTEMS USING CAPACITOR PLACEMENT