power grid presentation for upcomming projct

power grid presentation for upcomming projcts and india growth power grid presentation for upcomming projcts and india growth

1. INDUSTRIAL TRAINING
OVERVIEW OF G.I.S SUBSTATION
UNDERTAKEN AT
POWERGRID CORPORATION OF INDIA LIMITED (PGCIL),
MAHARANIBAGH, NEW DELHI
BY:
DEBASHREE GANTAYAT
8EL-015
4
TH
YEAR
BRANCH: ELECTRICAL ENGG .

2. Incorporatedon23rdOctober,1989fortheEstablishmentandOperation
ofRegionalandNationalPowerGridstofacilitatetransferofelectricpower
withinandacrosstheregionswithreliability,securityandeconomy,on
soundcommercialprinciples.
Startedcommercialoperationfrom1992-93withamalgamationofassets
andmanpowerfrompowerutilitieswithdiverseculture.
PowerGridwheelsabout51%ofthetotalpowergeneratedinIndiaonits
transmissionnetwork.PowerGridhasapanIndiapresencewitharound82,045
Circuit-kmofTransmissionnetworkand135nos.ofEHVAC&HVDCsub-
stationswithatotaltransformationcapacityof91,945MVA.
Govt.ofIndiahasconferredNAVRATNAstatustoPOWERGRIDinMay`08,the
highesthonourforaPublicSectorEnterprise.
POWERGRID CORPORATION OF INDIA LTD.

3. PGCIL -AREAS OF OPERATION
1. Development of
CentralSector
Transmission System
2. Grid Management
3. Telecom (handled by
POWERTEL) 4. Consultancy National
& International
•POWERGRID is also carrying out projects related to
distribution, sub-transmission and rural electrification works in
some states.

4. SUBSTATION-INTRODUCTION
•SUBSTATION:
The assembly of apparatus which can be used to change the characteristics of electrical
supply is called a substation.
•FUNCTIONS OF SUBSTATION:
1.It reduces voltage to a low level.
2.Can be used as switching stations.
3. Can be used as converting stations.
•TYPES:
1. AIR INSULATED SUBSTATION (AIS):
An electric power substation that has the bus bars and equipment terminations generally open to
air and utilizes I insulation properties of ambient air for insulation to ground is known as air
insulated substation.
2.GAS INSULATED SUBSTATION (GIS ):
A gas insulated substation is an electrical substation in which the major structures are contained in
a sealed environment with sulphur hexafluoride gas as the insulating medium.

5. POWERGRID –G.I.S SUBSTATION

6. ADVANTAGES OF GAS INSULATED
SWITCHGEAR (GIS) SUBSTATION
•Less spacerequirement and flexible design.
•Reduced maintenance.
•High Reliabilityand safety.
•Less Manpowerrequirement.
•Less time for Erectionas compared to AIS substation.
•SF6 Gasis used as insulating medium:good Dielectric
strength.
•GIS can even be installed in a building & in hilly regions
(uneven surface).
•No noise& Radio interference.

7. SWITCHYARD EQUIPMENTS
LIGHTNING ARRESTER
•POSITION IN SWITCHYARD:positioned always
at the entry of any incoming or outgoing
transmission lines.
•They are connected very first to the HV lines;
secondly it is also connected at the terminals of
costly equipments (like Transformers and shunt
reactors) in parallel.
•USE: Lightning Arrester protects the transmission
line and Power equipments from switching surges
and lightning surges.
•TYPES: -Basically there are two types of
lightning arresters.
i. Gapped lightning Arresters.
ii. Gapless lightning Arresters.

8. LIGHTNING ARRESTER...
CONNECTION:-Normally LA is connected
across the conducting terminal(of
transmission line & power equipments) and
earthvia surge counter.
WORKING:
•It basically consists of a stack of ZnOdiscs
mounted in sealed porcelain housing.
•Acts as non-linear resistor: it provides high
resistance to power frequency voltages and
low resistance to switching and lightning over
voltages. During high switching surges or
during heavy lightning over voltages LA divert
the surge through it to protect power
equipments.
ZnO Grain
Resistance
Barrier Resistance Barrier Capacitance
Fig: -Equivalent Circuit of LA

9. CAPACITIVE VOLTAGE TRANSFORMER (CVT)
(PARALLEL CONNECTION WITH GROUND)
•CVT is the equipment immediate next
to the lightning arresterat terminal
end of power transmission line.
• CVT has following main three
functions-
1. ReduceS the high voltage at measurable level.
2. Metering.
3. Protection.
4. PLCC (Power Line Carrier Communication)
–CVT has 3 cores. Its output
voltage is 110V.
NEUTRAL POINT
EMU
A
HF POINT
B
CORE-1
CORE-2
CORE-3

10. WAVE TRAP
(IN SERIES WITH GROUND)
POSITION IN SWITCHYARD: -
The Wave trap is inserted between the
carrier coupling point of CVT and the
station equipments.
PURPOSE: -
•To provide high impedanceto carrier
frequencies while maintaining negligible
impedance to power frequency current.
•Line traps have to carry
the power line current continuously and
under system
fault condition heavy short circuit current
flow through
them momentarily.
NEUTRAL
POINT
EMU
A
HF
POIN
T
B
COR
E-1
COR
E-2
COR
E-3
CVT
WT
FROM
LINE SIDE
FROM
BUS SIDE

11. FIGURE SHOWING L.A, WAVE TRAP AND C.V.T

12. INTER-CONNECTING TRANSFORMER (ICT)
•The primary and secondary
windingsare connected to the
respective voltage level bus via
Circuit breaker, Current transformer
and Isolators.
•The main purpose of ICT:
1. transform the power from higher
voltage level to low voltage level
(i.e. from 400 kV to 220 kV).
2.It also provides power to the
substation using the tertiary
windings (33kV).
Fig: -Equivalent Circuit of ICT
LV
coil
IV
coil
HV
coil
Taps

13. INTER-CONNECTING TRANSFORMER (ICT)
CONSTRUCTION -
1. TRANSFORMER CORE
2. TRANSFORMER WINDINGS
FITTINGS & ACCESSORIES
• MAIN TANK
• CONSERVATOR
• RADIATORS
• TRANSFORMER OIL
• OLTC (On-Load Tap Changer)
• BUSHINGS
• BUCHHOLZ RELAY
• PRV (Pressure Relief Valve)
• COOLING PUMPS
• SILICA GEL BREATHERS
• MARSHALLING BOX
• TURRET CT’s & NEUTRAL CT’S
Fig: -Internal Structure of Transformer tank
CORE
WINDING
TERMINAL

14. BUS ISOLATOR
•Bus Isolatoris placed after the
Circuit breaker (CB) seeing from line
incoming end.
•Earth switch is also coupled there
with the isolator at line side.
•Bus Isolator has following main
functions:
1.To isolate the bus during shutdowns
after opening of CB.
2.To provide earthing by associated
earth switchto bus.
•It basically consist of two contacts
namely male contactand female
contact.
MALE
CONTACT
FEMALE
CONTACT
SUPPORT
INSULATOR
STRUCTU
RE
ISOLATOR
MB
E/S MB
CORONA
SHIELD

15. BUS BARS :
•Bus Bar is spread through out the sub station area for connecting various
lines and ICT’S on it.
•Purpose of Bus bar is to provide connectivitybetween input and outgoing
circuits.
220 KV BUS-1
220 KV BUS-2
TRANSFER BUS
DOUBLE BUS SINGLE BREAKER SCHEME

16. CIRCUIT BREAKER
•Circuit breakeris connected after
the line isolator if we watch from
line side (between line isolator &
bus isolator)
•The main function of Circuit
Breaker (CB) is to make and break
the circuit onlinei.e. on-load
condition.
•The pole of Circuit breaker is
made up with three main
components: -
1.The interrupter chambers
2.The support column
3.The housing of the mechanism
Main
InterrupterPre-Insertion
Resistance
Grading
Capacitance
Fig: -Equivalent Circuit of CB

17. CURRENT TRANSFORMER (CT)
•Current transformeris placed just after the circuit breakertowards line side.
•CT consists of 5 cores.
•Current transformer is used for following two purposes:
1. Protectionof Line or Equipments.
2. Monitoringof primary currents.
Current transformers step downthe currentfrom high value to a low value.
Their current ratio is substantially constant for given range of primary
current and phase angle error is within specified limits.
Primary winding
Secondary winding
Fig: -Equivalent circuit of Current Transformer

18. PROTECTION SYSTEM
•Relays are replaced over the years, thereby helps in reduction
in size and improvement in function.
•Various relays used are :-
1.ELECTROMECHANICAL RELAYS -They work on the
principle of a mechanical force.
2.STATIC RELAYS -Their design is based on the use of
analog electronic devices.
3.DIGITAL RELAYS –They use a microprocessor to
implement the protection algorithm
4.NUMERICAL RELAYS –They are viewed as natural
developments of digital relays.

19. FIRE FIGHTING SYSTEM
–Fire fighting system consists of:
1. Smoke detectors.
2. Fire extinguishers.
3. Hydrant system.
4. Emulsifier system.
•It is placed in control room premise in separate room where HVW motor,
Jockey pump and Diesel pumpall things are kept.
•It is used in substation for extinguishing fire of any nature on ICT’s,
Reactors and other Control room equipments.
•It consists of HVW motor, Diesel Engine, Jockey pumps.

20. POWER LINE CARRIER
COMMUNICATION (PLCC)
•High Voltage (HV) and Extra High Voltage (EHV) Transmission linesthemselves act as a
medium for sending communication signalsapart from electric power.
•Various equipments used are-
1.Wave trap
2.Capacitor voltage transformer
3.Line Monitoring Unit
4.Balancing of transformer
5. Lightning arrester, earth switch,
ADVANTAGES OF PLCC :
•Transmission reliability is high.
•Transmission is not subjected to any variation from atmospheric or ionosphere
conditions.
DISADVANTAGES OF PLCC :
•Cost of insulation of communication equipment and transmission lines is very high.
•Noise level will be high because of interference of corona.
•High speed data transfer is not possible because of band width limitations.

21. SCADA
•SCADA(supervisory control and data acquisition)
generally refers to industrial control systems: computer
systems that monitor and control industrial, infrastructure, or
facility-based processes.
•Basically consist of following components –
1.Human -machine Interface (HMI)
2.Supervisory system
3.Remote terminal Units (RTU)
4.Programmable Logic Devices (PLC)