Electric power system ppt

1. ELECTRIC POWER SYSTEM
Submitted by :-krypton

2. CONTENT :-
Introduction
Generation
Transmission
Distribution
Load

3. INTRODUCTION
The power system is a network which consists
Generation , transmission and distribution system.
It uses the form of energy(like coal and diesel)
and convert into electrical
Energy.

4. Structure of power system
Generation Transmission
Distribution
Load

5. GENERATION
Generation is simply the conversion of energy
from one form to another.
The three major types of generation are:
FOSSIL
HYDRO
NUCLEAR

6. FOSSIL
Fossil fuels such as coal, oil and gas are
burned to generate electricity.
The machines used in fossil generation are
high speed but slow starting.
The main issues are environmental as
burning of fuel causes pollution therefore
low sulphur content fuel is used.

7. HYDRO
In hydro plants, electric power is generated by the water
flowing through a turbine which is coupled
solidly to a generator.
Hydro machines are slow machines but they are quick
starting and have a good ramping rate.

8. TRANSMISSION
Electric power transmission is the bulk movement
of electrical energy from a generating site, such as a power
plant, to an electrical substation. The interconnected lines
which facilitate this movement are known as a transmission
network.
The transmission system consists of a network of
overhead lines or in densely populated areas,
underground cables.

9. TYPES OF POWER
TRANSMISSION
The two general types of power transmission are
:
1) Overhead lines
2) Underground cables

10. OVERHEAD LINES
Overhead lines are of two types
1) AC line
2) DC line

11. AC LINE
The overhead ac lines are applied on
power systems at voltages in the
range of 115 KV to 800 KV.

12. Advantages of AC
Transmission:
1.Power can be generated at high voltages as there is no
commutation problem.
2.Ac voltages can be conveniently stepped up or stepped down.
3.High voltage transmission of ac power reduces losses.

13. Disadvantages of
AC transmission:
1.Due to skin effect, more copper is required.
2.Construction of AC transmission lines is more complicated as well
as costly.
3.Problems of inductances and capacitances exist in transmission
lines.
4.Effective resistance of ac transmission lines is increased due to
skin effect.

14. DC LINE
In this mode of transmission, the three phase,
60 Hz voltages and currents are converted
to dc, transmitted on a dc line and are
converted back to ac at the other end.
The massive transmission of electricity is in the form
of DC over long distance.

15. USESOF THE DC
TRANSMISSION
To connect two systems operating at different
frequencies.
For long underground or under water transmission.
For long distance overhead transmission.
Moreover DC transmission is chosen over AC because it
is less expensive than AC over very long distances.

16. COMPONENTS OF A
TRANSMISSION LINE
Conductors
Ground wires
Insulators
Towers

17. A Conductors is an type of material that allows to flow of
charge (electrical current) in one or more direction.
The Ground wire acts as a shield to protect the
energized conductors from lightning strokes.
Insulators suspend the energized phase conductors
and insulate them from grounded tower.
The Tower support the conductors and is the most
visual part of a T.L.

18. Underground cables are used in very densely populated
areas but they are rarely used because they are more
expensive as the require insulating materials instead of air
to separate the conductors from each other and from
ground.
CABLES
TYPES OF CABLES-
OIL FILLED PIPE TYPE CABLE
OIL FILLED SELF CONTAINED CABLE
SOLID DIELECTRIC CABLE
SF6 CABLE

19. ADVANTAGES OF
CABLES
1.Suitable for congested urban areas.
2.Require low maintenance as damage rate is low.
3.Ensure small voltage drops.
4.Not easy to steal and damage.
5.Avoid the chances of illegal connections.
6.Protection from environmental stresses like wind,
storms, and thunder.

20. DISADVANTAGES OF CABLES
1.Difficult to repair.
2.Difficulty in finding the actual location of
underground buried cables.
3.Unwanted digging can cause environmental
pollution.
4.High installation cost.

21. DISTRIBUTION
Electric power distributions is the final stage in the
delivery of electric power, it carries electricity from the
transmission system to individual consumers. Distribution
substation connect to the transmission system and lower
the transmission voltage to medium voltage ranging
between 2kv and 35kv with the use of transformer.
Primary distribution lines carry this medium voltage power
to distribution transformer located near the customer’s
premises.

22. LOAD
The utilization of electric power is
collectively called load. This
includes
the uses of electricity in homes,
factories, offices and for
recreation,
entertainment, etc.

23. SYSTEM VOLTAGES
Generation voltages are in the range of
12-35KV.
Transmission voltages are in the range of
115-800 KV.
Distribution voltages are in the range of
4-35 KV.
Loads operate at variety of voltages due to
their diverse nature.