devendra

1. ELEMENTS OF THEELEMENTS OF THE
POWER SYSTEMPOWER SYSTEM
Submitted ToSubmitted To
Mr. Shahbaz PervezMr. Shahbaz Pervez
Submitted BySubmitted By
Bilal Aslam 03F -EE-17Bilal Aslam 03F -EE-17
Salman Tahir 03F-EE-55Salman Tahir 03F-EE-55

2. POWERPOWER SYSTEMSYSTEM
The electrical power system provides aThe electrical power system provides a
means ofmeans of generatinggenerating,, transmittingtransmitting andand
distributingdistributing energy in the form of electricenergy in the form of electric
current, to the ultimate users, thecurrent, to the ultimate users, the loadload..
GenerationGeneration,, TransmissionTransmission,, DistributionDistribution andand
LoadLoad form the four basic elements orform the four basic elements or
subsystemssubsystems of a power systemof a power system

3. SUBSYSTEMSSUBSYSTEMS

4. GENERATIONGENERATION
Generation is simply the conversion ofGeneration is simply the conversion of
energy from one form to another.energy from one form to another.
The three major types of generationThe three major types of generation
are:are:
 FOSSILFOSSIL
 HYDROHYDRO
 NUCLEARNUCLEAR

5. FOSSILFOSSIL
Fossil fuels such asFossil fuels such as coal, oil and gascoal, oil and gas areare
burned to generate electricityburned to generate electricity
The machines used in fossil generation areThe machines used in fossil generation are
high speed but slow startinghigh speed but slow starting
The main issues are environmental asThe main issues are environmental as
burning of fuel causes pollution thereforeburning of fuel causes pollution therefore
low sulphurlow sulphur content fuelcontent fuel is usedis used

6. HYDROHYDRO
In hydro plants, electric power isIn hydro plants, electric power is
generated by the water flowinggenerated by the water flowing
through a turbine which is coupledthrough a turbine which is coupled
solidly to a generatorsolidly to a generator
Hydral machines areHydral machines are slow machinesslow machines
but they are quick starting and havebut they are quick starting and have
a gooda good ramping rateramping rate

7. NUCLEARNUCLEAR
In nuclear plants the basic cycle is similar toIn nuclear plants the basic cycle is similar to
that of fossil plant but the required heat isthat of fossil plant but the required heat is
provided by theprovided by the nuclear reactionnuclear reaction ratherrather
from burning fuelsfrom burning fuels
Due to the stringent governmentDue to the stringent government
requirements about the safety of nuclearrequirements about the safety of nuclear
plants, their design and operation areplants, their design and operation are
much more complicated than the fossil ormuch more complicated than the fossil or
hydro unitshydro units

8. TRANSMISSIONTRANSMISSION
The transmission system consists of aThe transmission system consists of a
network ofnetwork of overhead linesoverhead lines or inor in
densely populated areas,densely populated areas, underunder
ground cablesground cables
The lines are designed to transmitThe lines are designed to transmit
large amounts of power from point oflarge amounts of power from point of
generation to the load areageneration to the load area

9. CLASSIFICATION OFCLASSIFICATION OF
TRANSMISSION LINESTRANSMISSION LINES
We classify transmission lines withWe classify transmission lines with
reference to:reference to:
 VoltageVoltage
 DistanceDistance
 A.C or DCA.C or DC

10. VOLTAGEVOLTAGE
 Ultra high voltage transmission lines(1000Ultra high voltage transmission lines(1000
KV)KV)
 Extra high voltage transmission lines(745Extra high voltage transmission lines(745
KV)KV)
 High voltage transmission lines(200 KV)High voltage transmission lines(200 KV)
 Medium voltage transmission line(132 KV)Medium voltage transmission line(132 KV)

11. DISTANCEDISTANCE
 Long length T.L (> 150 KM )Long length T.L (> 150 KM )
 Medium length T.L (50-150 KM)Medium length T.L (50-150 KM)
 Short length T.L (<50 KM )Short length T.L (<50 KM )

12. A.C OR D.CA.C OR D.C
The transmission line may be ac or dcThe transmission line may be ac or dc
depending upon the applicationdepending upon the application

13. TYPES OF POWERTYPES OF POWER
TRANSMISSIONTRANSMISSION
The two general types of powerThe two general types of power
transmission are :transmission are :
 Overhead linesOverhead lines
 Underground cablesUnderground cables

14. OVERHEAD LINESOVERHEAD LINES
Overhead lines are of two typesOverhead lines are of two types
 AC lineAC line
 DC lineDC line

15. AC LINESAC LINES
The overhead ac lines are applied onThe overhead ac lines are applied on
power systems at voltages in thepower systems at voltages in the
range ofrange of 115 KV115 KV toto 800 KV800 KV

16. COMPONENTS OF ACOMPONENTS OF A
TRANSMISSION LINETRANSMISSION LINE
 ConductorsConductors
 Ground wiresGround wires
 InsulatorsInsulators
 TowersTowers

17. ConductorsConductors are either solid round,stranded orare either solid round,stranded or
bundled. Stranding provides flexibilitybundled. Stranding provides flexibility
TheThe Ground wireGround wire acts as a shield to protect theacts as a shield to protect the
energized conductors from lightning strokesenergized conductors from lightning strokes
InsulatorsInsulators suspend the energized phase conductorssuspend the energized phase conductors
and insulate them from grounded towerand insulate them from grounded tower
TheThe TowerTower support the conductors and is the mostsupport the conductors and is the most
visual part of a T.Lvisual part of a T.L

18. DC TRANSMISSION LINEDC TRANSMISSION LINE
In this mode of transmission, theIn this mode of transmission, the threethree
phase, 60 Hzphase, 60 Hz voltages and currentsvoltages and currents
are converted to dc, transmitted on aare converted to dc, transmitted on a
dc line and are converted back to acdc line and are converted back to ac
at the other endat the other end

19. USES OF THE DCUSES OF THE DC
TRANSMISSION LINETRANSMISSION LINE
 To connect two systems operating atTo connect two systems operating at
different frequenciesdifferent frequencies
 For long underground or under waterFor long underground or under water
transmissiontransmission
 For long distance overheadFor long distance overhead
transmissiontransmission

20.  DC lines are sometimes calledDC lines are sometimes called
asynchronous tiesasynchronous ties since they can besince they can be
used to inter connect two systemsused to inter connect two systems
operating at different frequenciesoperating at different frequencies
 Moreover DC transmission is chosenMoreover DC transmission is chosen
over AC because it is less expensiveover AC because it is less expensive
than AC over very long distancesthan AC over very long distances

21. CABLESCABLES
Underground cables are used in veryUnderground cables are used in very
densely populated areas but they aredensely populated areas but they are
rarely used because they are morerarely used because they are more
expensive as they require insulatingexpensive as they require insulating
materials instead of air to separatematerials instead of air to separate
the conductors from each other andthe conductors from each other and
from groundfrom ground

22. DISADVANTAGES OF CABLESDISADVANTAGES OF CABLES
There are also some technicalThere are also some technical
disadvantages associated withdisadvantages associated with
underground cables. One majorunderground cables. One major
problem is the very high capacitanceproblem is the very high capacitance
inherent in the underground cables.inherent in the underground cables.
This capacitance give rise toThis capacitance give rise to chargingcharging
currents.currents. Special equipments mustSpecial equipments must
be installed to compensate for thebe installed to compensate for the
effect of charging currents, whicheffect of charging currents, which
adds to the costadds to the cost

23. TYPES OF CABLESTYPES OF CABLES
 OIL FILLED PIPE TYPE CABLEOIL FILLED PIPE TYPE CABLE
 OIL FILLED SELF CONTAINED CABLEOIL FILLED SELF CONTAINED CABLE
 SOLID DIELECTRIC CABLESOLID DIELECTRIC CABLE
 SF6 CABLESF6 CABLE

24. DISTRIBUTIONDISTRIBUTION
The distribution system consists of aThe distribution system consists of a
network overhead lines andnetwork overhead lines and
underground cables by which theunderground cables by which the
power is distributed to the ultimatepower is distributed to the ultimate
users of electricity that is theusers of electricity that is the loadload

25. LOADLOAD
TheThe utilizationutilization of electric power isof electric power is
collectively calledcollectively called loadload. This includes. This includes
the uses of electricity inthe uses of electricity in homes,homes,
factories, offices and for recreation,factories, offices and for recreation,
entertainment, etcentertainment, etc

26. SYSTEM VOLTAGESSYSTEM VOLTAGES
Generation voltages are in the range ofGeneration voltages are in the range of
12-35KV12-35KV
Transmission voltages are in the range ofTransmission voltages are in the range of
115-800 KV.115-800 KV.
Distribution voltages are in the range ofDistribution voltages are in the range of
4-35 KV.4-35 KV.
Loads operate at variety of voltages due toLoads operate at variety of voltages due to
their diverse naturetheir diverse nature

27. POWER IS TRANSMITTEDPOWER IS TRANSMITTED
AT HIGH VOLTAGEAT HIGH VOLTAGE
RATHER HIGH CURRENTRATHER HIGH CURRENT

28. Power transmitted is directlyPower transmitted is directly
proportional to product ofproportional to product of VV andand II
but losses are directly proportional tobut losses are directly proportional to
II22 ,,
therefore to transmit power withtherefore to transmit power with
minimum loss we use high voltageminimum loss we use high voltage