Voltage regulation and power losses

1. 080450109207 Maheta Nimesh
090450109039 Sadhu Manish
Power System Practice
And Designed

2. Voltage Regulation in power system
 All the equipments in the electrical network are
designed to operate with a certain voltage range.
 Due to voltage drop occurring in every section of
the system, the equipment which is farthest from
the sub station would receives the lowest voltage.
 Generally, lower line voltage drop and line losses
are desirable and a large conductor size should
be used transmission of voltage for this purpose.

3.  The voltage drop over the line is given by IZ, where Z=R
+ jX. The value of R reduces with increase in size of
conductor but reactance X which is the function of
spacing does not change with conductor size.
 The voltage regulation defines the concept of maintaining
a relatively stable voltage level at the consumer’s end.
 There are three main assumptions for voltage regulation
which are following :

4. a) The voltage variations must not be greater than
certain established limits.
b) The voltage must not be subjected to serious
fluctuation or flicker.
c) The voltage must approximate to some
optimum level.
 Percentage voltage regulation for lagging
power factor is given by

5. Where,
i.e., sending end voltage = receiving end voltage +
load voltage
Percentage voltage regulation for leading power
factor is given by
where, = sending end line voltage
= receiving end line voltage
I = line current

6. R = line resistance
X = line reactance
cosΦ = power factor
 The methods of voltage regulations used on the
distribution systems are
1) Transformer Taps ± % & ± 5 %
2) Auto control Induction type voltage regulators
3) Booster and Automatic tap changer
4) Capacitors

7.  The transformer tap setting may be arranged in
such away so as to maintain the voltage drop
within 5%.
 The automatic voltage boosters are less
expensive than induction one and they can
improve service in low density areas on long
rural lines.
 The boosters and automatic tap changers are
installed on long distribution lines so as to
regulate voltage on the feeders.
 The shunt capacitors are installed on the
distribution system to reduce the current and to
improve the voltage regulation and to reduce
energy losses in every part of the system.

8. Power System Losses
 In electrical system, often the constant no
load losses and the variable load are to be
assessed alongside, over long reference
duration, towards energy loss estimation.
 For example the cable losses in any industrial
plant will be up to 6 % depending upon the
size and complexity of the distribution system.
 Note that all of these are current dependent.

9.  In system losses optimization, the various
options available which are following:
1. Relocating transformer and substation near to
load centers.
2. Power factor improvement by incorporating
capacitors at load end.
3. Optimum loading for transformers in the
system.
4. Minimizing losses due to weak lines in
distribution network such as junipers, loose
contacts, old brittle conductors.
5. Opting for lower resistance all aluminum alloy
conductor in place of aluminum conductor steel
reinforced lines.

10. Losses in component
 Various kinds of losses occur in our power
system components such as the loss in step
up transformers, transmission lines, primary
distribution feeders, distribution transformers,
distributors.
 In generators, two kinds of losses occur. One
is
loss which depends upon the loading
condition and another iron loss is which only
depends upon the operating voltage.

11.  The total power loss does not depend upon the
power factor. Therefore, the rating is always done in
MVA.
 The rating of induction motor is always done in KW
or MW.

12. Measurement of Losses
 A large number copper or aluminum
conductors are used to form the transmission
path.
 The resistance of the long distance
transmission conductors is to be minimized.
 Capacitors are used to correct power factor by
causing the current to lead voltage.
 Transformers are placed at strategic location
throughout the system to minimize power
losses in the transmission and distribution
system.

13.  We know, Efficiency =
Where, Total power = useful power + power loss
power loss = total power – useful power
Or
= 1 -
= 1 - efficiency

14. Thank You