A
presentation
ON
RRVPNL, 132 KV GSS (GIS) OLD POWER HOUSE
JODHPUR (RAJ.)
submitted in partial fulfilment
for the award of the Degree of
BACHELOR OF TECHNOLOGY
IN
Department of Electrical Engineering
Submitted To :
Mr. Vikas Bhalla
Submitted By:
Harish kumar
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GAS INSULATED SUBSTATION
B Y:
HA R I SH K UM A R
ELECTRICAL
E NGI N E E R I N G
1510-15
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3
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CONTENTS:
Substation
Conventional substations (AIS)
Limitations of AIS
The need for GIS
Introduction to GIS
Properties of SF6
GIS assembly
Advantages of GIS
Design features
Drawbacks
SF6 – Environmental concerns
SF6 /N2 mixtures
Future trends in GIS
Conclusion.
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SUBSTATION:
•
An assembly of apparatus installed to control
transmission and distribution of electric power.
A:PRIMARY POWER LINES' SIDE B:SECONDARY POWER LINES' SIDE
1.PRIMARY POWER LINES 2.GROUND WIRE 3.OVERHEAD LINES 4.TRANSFORM ER FOR
MEASUREMENT OF ELECTRIC VOLTAGE 5.DISCONNECT SWITCH 6.CIRCUIT BR EAKER
7.CURRENT TRANSFORMER 8.LIGHTNING ARRESTER 9.MAIN TRANSFORMER 10 .CONTROL
BUILDING 11.SECURITY FENCE 12.SECONDARY POWER LINES
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AIR INSULATED SUBSTATION(AIS):
Air used as a dielectric.
Normally used for outdoor substations.
In very few cases used for indoor substations.
Easy to expand (in case that space is not an issue)
Excellent overview, simple handling and easy access.
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LIMITATIONS OF AIS:
Large dimensions due to statutory clearances and poor
dielectric strength of air.
Insulation deterioration with ambient conditions and
susceptibility to pollutants.
Wastage of space.
Life of steel structures degrades.
Seismic instability.
Large planning & execution time.
Regular maintenance of the substation required.
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INTRODUCTION TO GAS INSULATED
SUBSTATION
What is GIS?
 A gas insulated substation is an electrical substation in which the major
structures are contained in a sealed environment with sulfur hexafluoride
gas (SF6) as the insulating medium.
Where and why Gas Insulated Substations are
used ?
 Gas Insulated Substations are used where there is space for providing the
substation is expensive in large cities and towns. In normal substation the
clearances between the phase to phase and phase to ground is very large.
Due to this, large space is required for the normal or Air Insulated
Substation (AIS).
 But the dielectric strength of SF6 gas is higher compared to the air, the
clearances required for phase to phase and phase to ground for all
equipments are quite lower. Hence, the overall size of each equipment and
the complete substation is reduced to about 10% of the conventional air
insulated substation
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THE NEED FOR G.I.S:
Non availability of sufficient space.
Difficult climatic and seismic conditions at site.
Urban site (high rise building).
High altitudes.
Limitations of AIS.
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GAS INSULATED SUBSTATION:
Introduction:
Compact, multi-component assembly.
Enclosed in a ground metallic housing.
Sulphur Hexaflouride (SF6) gas – the primary insulating
medium.
(SF6) gas- superior dielectric properties used at moderate
pressure for phase to phase and phase to ground
insulation
Preferred for voltage ratings of 72.5 kV, 145 kV, 300 kV and
420 kV and above.
Various equipments like Circuit Breakers, Bus-Bars, Isolators,
Load Break Switches, Current Transformers, Voltage
Transformers, Earthing Switches, etc. housed in metal
enclosed modules filled with SF6 gas.
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PROPERTIES OF SF6:
•
•
•
N O N - T O X I C , V E R Y S T A B L E C H E M I C A L LY.
•
I N S U L AT I N G P R O P E R T I E S 3 - T I M E S T H AT
OF AIR.
•
•
•
MAN-MADE.
LIFETIME – VERY LONG (800 TO 3200
YEARS!).
C O LO R L E S S & H E AV I E R T H A N A I R .
A L M O S T W AT E R I N S O L U B L E .
NON INFLAMMABLE.
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Kalisindh Thermal Power
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GIS ASSEMBLY:
ESSENTIAL PARTS OF GIS:
1. Bus bar
2. Circuit Breaker
3. Disconnector (line or bus)
4. Earthing switch (line or bus)
5. Current transformer (feeder / bus)
6. Voltage transformer (feeder/ bus)
7. Feeder Disconnector
8. Feeder Earthing switch
9. Lightning / Surge Arrester
10. Cable termination
11. Control Panel.
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BUS BAR
 When a number of lines operating at the same voltage have to directly
connect electrically bus bar are used as the common electrical
component.
 There are following bus at the 132 gss:• 132 kv main bus bar
• 132 kv auxiliary bus bar
ISOLATOR
 Isolator is used to break the circuit under off-load
where as on-load circuit breaking is done by circuit
breaker
 Isolators are classified as:•
Off load isolator
•
On load isolator
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CIRCUIT BREAKER
An automatic switch that stops the flow of
electric current in a suddenly overloaded or
otherwise abnormally stressed electric
circuit.
Types of circuit breaker:•
Vaccum circuit breaker
•
SF6 Circuit breaker
•
Air blast circuit breaker
• Oil circuit breaker
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CIRCUIT BREAKER OPERATION MECHANISM
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INSULATOR
 Barrier insulator: The GIS is sectionalized into
individual gas compartments by means of gas-tight
barrier insulators. By this, the impact of extension or
internal faults on the overall installation is reduced
to a minimum, and control, supervision and
maintenance are greatly eased. All flange
connections are sealed by means of age-resistant
O-rings. Due to the gas tight design of the insulators
no leakage between components can occur.
 Support insulator: Support insulators are used to
mechanically support the conductors. They mainly
used for long SF6 bus duct connection.
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CURRENT TRANSFORMER
Current transformer is used for measurement of
alternating electric current.
The objective of C.T. is :Reduce the scale of the metering scale.
Insulated the measuring instrument from
voltage.
•
Used for protective system
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POTENTIAL TRANSFORMER
Potential transformer is used for step down the line
voltage.
PT is connected in prallel with line.
Secondary voltage of the PT is generally 110v.
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CAPACITOR VOLTAGE
TRANSFORMER
 A capacitor voltage transformer
consists of a Capacitor Voltage Divider
(CVD) and an inductive Intermediate
Voltage Transformer (IVT).
 The rated voltage of the complete
capacitor voltage transformer
determines the ratio at the capacitor
voltage divider.
 It is more convenient to make an
Inductive voltage transformer for
lower voltage levels and let the CVD
take care of the high voltage.
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LIGHTENING ARRESTER
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LIGTHNING ARRESTOR
 Lightening arrester is used to protect the power station
sub station and transmission line against the voltage wave
reaching there.
 It is also known as surge diverter which is connected
between line and earth to divert the incoming high voltage
to earth.
 It is the first equipment in a substation.
 Generally arresters are connected in parallel with the
equipment to be protected, typically between phase and
earth for three phase installations.
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GIS ASSEMBLY:
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Supervisory Control And Data Acquisition
(SCADA)
 Supervisory Control and Data Acquisition (SCADA) offers the ease of
monitoring of sensors placed at distances, from one central location.
 SCADA systems are used to monitor and control a plant or equipment in
industries such as telecommunications, water and waste control, energy,
oil and gas refining and transportation.
 A SCADA system gathers information, such as where a leak on a pipeline
has occurred, transfers the information back to a central site, alerting the
home station that the leak has occurred, carrying out necessary analysis
and control, such as determining if the leak is critical, and displaying the
information in a logical and organized fashion.
 SCADA systems can be relatively simple, such as one that monitors
environmental conditions of a small office building, or incredibly complex,
such as a system that monitors all the activity in a nuclear power plant or
the activity of a municipal water system.
 SCADA systems were first used in the 1960s.
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SCADA CONTROL ROOM
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LARGE SCADA DISPLAY
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ADVANTAGES :
Occupies very less space (1/10th) compared to ordinary
substations.
Hence, most preferred where area for substation is small
(eg: Cities)
Most reliable compared to Air Insulated Substations.
Number of outages due to the fault is less
Maintenance Free.
Can be assembled at workshop and modules can be
commissioned in the plant easily.
Pollution free
Explosion proof & fire proof installation
Increased safety
Easy operation & long life
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DESIGN CHALLENGES:
1. SAFET Y:
• O P T I M I Z I N G O P E R AT I N G E L E C T R I C A L S T R E S S E S
TO SAFE LEVELS BY BETTER INTER ELECTRODE
SPACING .
• INCREASING THE GAS VOLUME AND THE
THERMAL INERTIA OF THE SYSTEM TO ENHANCE
C O O L I N G A N D R E TA I N I N S U L AT I O N S T R E N GT H .
2. HIGH RELIABILITY:
• S U P E R I O R C O N TAC T SYST E M S FO R C I RC U I T
BREAKERS AND
DISCONNECTORS.
• M U LT I - C O N TAC T A N D F R I C T I O N F R E E S U R FAC E S
I N C O R P O R AT E D F O R L O N G O P E R AT I N G C YC L E S .
• R U G G E D , T I M E P R O V E N O P E R AT I N G D R I V E S
USED.
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GIS FAILURE STATISTICS:
12.30%
12.40%
INSULATION FAILURE
57.30%
18.10%
MECHANICAL TROUBLE
GAS LEAK
OTHERS
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MAIN DRAWBACKS:
• HIGH
COST
•
•
•
•
•
C O MPA RE D
TO
C O N V E N T I O N A L S U B S TAT I O N ( A I S ) .
EXCESSIVE
DAMAGE
IN
CASE
OF
I N T E R N A L FA U LT.
D I A G N O S I S O F I N T E R N A L FA U LT A N D
R E C T I F Y I N G TA K E S V E R Y L O N G T I M E
( H I G H O U TAG E T I M E ) .
SF6
GAS
PRESSURE
MUST
BE
M O N I TO R E D I N E AC H C O M PA R T M E N T.
REDUCTION IN THE PRESSURE OF THE
SF6
GAS
IN
ANY
M O D U L E R E S U LT S I N F L A S H O V E R A N D
FA U LT S .
SF6 CAUSES OZONE DEPLETION AND
GLOBAL WARMING.
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SF6 – ENVIRONMENTAL CONCERNS:
•
•
•
•
•
I.
C U R R E N T LY , 8 0 % U S E D B Y E L E C T R I C A L
P O W E R I N D U S T R Y.
OTHER USES – MICRO-ELECTRONICS;
AL & MG PRODUCTION.
7000 METRIC TONS/ YR IN 1993.
REACHED 10,000 METRIC TONS/ YR BY
2 010 .
T W O A R E A S O F H E A LT H A N D
E N V I R O N M E N T A L I M P A C T:
THROUGH ITS NORMAL USE IN A
WORK PLACE – ARCING BYPRODUCTS.
I I . G L O B A L E N V I R O N M E N TA L I M PA C T OZONE DEPLETION AND GLOBAL
WARMING.
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SF6/N2 MIXTURES FOR GIS?
• S F 6 G A S – S P E C I F I C A L LY M E N T I O N E D
•
•
•
•
IN
KYOTO PROTOCOL .
SMALL QUANTITIES OF SF6 IN N2 CAN
IMPROVE DIELECTRIC STRENGTH
D R A S T I C A L LY.
ALL OF THE DIELECTRIC STRENGTH OF
S F 6 , N E A R LY, C A N B E A C H I E V E D B Y
ADDING LESS THAN 20% SF6 INTO N2.
SF6/N2 MIXTURES LESS SUSCEPTIBLE TO
EFFECTS OF FIELD NON UNIFORMIT Y
THAN PURE SF6.
T H U S M I T I G AT I N G T H E E F F E C T S O F
PA RT I C L E S A N D S U R FAC E P ROT RU S I O N S .
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FUTURE TRENDS:
•
•
•
•
•
•
C O M PAC T DE S I GN O F SWI TC H GE A R BY
USING THREE PHASE MODULES.
US E OF VAC UUM C I RC UI T B R E AK E R
C E L L S I N T H E M E D I U M H I G H V O LT A G E
GIS.
O P T I M I Z AT I O N O F G I S D E S I G N T O
ALLOW EASIER MAINTENANCE.
DEVELOPMENT OF DC GIS FOR
I N C O R P O R AT I N G I N T O E X P A N D I N G
N AT I O N A L / I N T E R N AT I O N A L H V D C
SYSTEMS.
SEARCH FOR REPLACEMENT GASES
FOR SF6.
THE MOST PROMISING
- AN 80%/20%
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CONCLUSION:
•
•
•
•
•
•
GIS – NECESSARY FOR EXTRA HV &
U LT R A H V
S O M E I M P O R TA N T A R E A S TO B E ST U D I E D
INCLUDE:
M O R E C O N S E R VAT I V E D E S I G N .
IMPROVED GAS HANDLING.
DECOMPOSITION PRODUCT MANAGEMENT
TECHNIQUES.
AC H I E V I N G & M A I N TA I N I N G H I G H L E V E L S
O F AVA I L A B I L I T Y R E Q U I R E – M O R E
I N T E G R AT E D A P P R O A C H T O Q U A L I T Y
CONTROL BY BOTH USERS AND
M A N U FAC T U R E S .
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